記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Sissa Medialab  

We study the latent heat and the pressure gap between the hot and cold phases at the first-order transition temperature T = Tc of SU(3) Yang-Mills theory, using the small flow-time expansion (SFtX) method based on the gradient flow. We first examine alternative procedures in the SFtX method - the order of the continuum and vanishing flow-time extrapolations. We confirm that the final results adopting the two orders, as well as other alternatives in which the perturbative order of the matching coefficients and the renormalization scale of the flow scheme are varied, are all consistent with each other. We also confirm ∆p is consistent with zero, as expected from the dynamical balance of two phases at Tc. For the latent heat in the continuum limit, we find ∆є/T4 = 1.117(40) for the spatial volume L3 corresponding to the aspect ratio Ns/Nt = TcL = 8 and 1.349(38) for Ns/Nt = 6. From hysteresis curves, we show that the entropy density in the hot phase is sensitive to the spatial volume, while that in the confined phase is insensitive.

DOI： 10.22323/1.396.0064

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Sissa Medialab  

DOI： 10.22323/1.396.0531

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

<title>Abstract</title>
Hopping parameter expansion is a useful tool for investigating heavy dynamical quarks in lattice quantum chromodynamics (QCD), though its range of applicability has sometimes been questioned. We study the convergence and the valid range of the hopping parameter expansion in determining the critical point (critical quark mass) of QCD with heavy quarks at finite temperature and density. On lattices with sufficiently large spatial extent, the terms in the hopping parameter expansion are classified into Wilson loop terms and Polyakov-type loop terms. We first study the case of the worst convergence in which all the gauge link variables are unit matrices and thus the Wilson loops and the Polyakov-type loops get their maximum values. We perform explicit calculation up to more than the 100th order of the hopping parameter expansion. We show that the hopping parameter expansion is convergent up to the chiral limit of free Wilson quarks. We then perform a Monte Carlo simulation to measure correlation among Polyakov-type loop terms up to the 20th order of the hopping parameter expansion. In previous studies, strong correlation between the leading-order Polyakov loop term and the next-to-leading-order bent Polyakov loop terms was reported and used to construct an effective theory to incorporate the next-to-leading-order effect by a shift of the leading-order coupling parameter. We establish that the strong correlation among Polyakov-type loop terms also holds at higher orders of the hopping parameter expansion, and extend the effective theory to incorporate higher-order effects up to high orders. Using the effective theory, we study the truncation error of the hopping parameter expansion. We find that the previous next-to-leading-order result for the critical point for Nt = 4 is reliable. For Nt ≥ 6, we need to incorporate higher-order effects in the effective theory.

DOI： 10.1093/ptep/ptac019

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その他リンク： https://academic.oup.com/ptep/article-pdf/2022/3/033B05/42829507/ptac019.pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society (APS)  

Finite-size scaling is investigated in detail around the critical point in the heavy quark region of nonzero temperature QCD. Numerical simulations are performed with large spatial volumes up to the aspect ratio Ns/Nt = 12 at a fixed lattice spacing with Nt = 4. We show that the Binder cumulant and the distribution function of the Polyakov loop follow the finite-size scaling in the Z(2) universality class for large spatial volumes with Ns/Nt >= 9, while, for Ns/Nt <= 8, the Binder cumulant becomes inconsistent with the Z(2) scaling. To realize the large-volume simulations in the heavy quark region, we adopt the hopping parameter expansion for the quark determinant: We generate gauge configurations using the leading-order action including the Polyakov loop term for Nt = 4, and incorporate the next-to-leading order effects in the measurements by the multipoint-reweighting method. We find that the use of the leading-order configurations is crucially effective in suppressing the overlapping problem in the reweighting and thus in reducing the statistical errors.

DOI： 10.1103/physrevd.104.114509

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その他リンク： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevD.104.114509/fulltext

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

<title>Abstract</title>
We study latent heat and the pressure gap between the hot and cold phases at the first-order deconfining phase transition temperature of the SU(3) Yang–Mills theory. Performing simulations on lattices with various spatial volumes and lattice spacings, we calculate the gaps of the energy density and pressure using the small flow-time expansion (SF$t$X) method. We find that the latent heat $\Delta \epsilon$ in the continuum limit is $\Delta \epsilon /T^4 = 1.117 \pm 0.040$ for the aspect ratio $N_s/N_t=8$ and $1.349 \pm 0.038$ for $N_s/N_t=6$ at the transition temperature $T=T_c$. We also confirm that the pressure gap is consistent with zero, as expected from the dynamical balance of two phases at $T_c$. From hysteresis curves of the energy density near $T_c$, we show that the energy density in the (metastable) deconfined phase is sensitive to the spatial volume, while that in the confined phase is insensitive. Furthermore, we examine the effect of alternative procedures in the SF$t$X method—the order of the continuum and the vanishing flow-time extrapolations, and also the renormalization scale and higher-order corrections in the matching coefficients. We confirm that the final results are all very consistent with each other for these alternatives.

DOI： 10.1093/ptep/ptaa184

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

In Sec. II C, Eqs. (50) and (51) for “linear+log fit” should read (Farmula Presented) and (Farmula Presented) espectively, where ΛMS=332(17) MeV is the QCD lambda parameter for three-flavor QCD quoted in the Particle Data Group [1]. The dotted curves for the linear+log fit in Figs. 2–7, 10, and 12 were showing the results of nonlinear fit by error. The correct figures are given in this Erratum. The caption of Fig. 10 is slightly modified to quote Eq. (51). (Figure Presented) Analyses in the paper have been done adopting the above correct formulas, and thus the results and the tables as well as other figures are unchanged.

DOI： 10.1103/PhysRevD.102.059903

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.363.0071

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.363.0191

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.363.0088

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society (APS)  

We study thermodynamic properties of N-f = 2 + 1 QCD on the lattice adopting a nonperturbatively Ooa+-improved Wilson quark action and the renormalization group-improved Iwasaki gauge action. To cope with the problems due to explicit violation of the Poincare and chiral symmetries, we apply the small flow-time expansion (SFtX) method based on the gradient flow, which is a general method to correctly calculate any renormalized observables on the lattice. In this method, the matching coefficients in front of operators in the small flow-time expansion are calculated by perturbation theory thanks to the asymptotic freedom around the small flow-time limit. In a previous study using one-loop matching coefficients, we found that the SFtX method works well for the equation of state extracted from diagonal components of the energy-momentum tensor and for the chiral condensates and susceptibilities. In this paper, we study the effect of two-loop matching coefficients which have been calculated by Harlander et al. recently. We also test the influence of the renormalization scale in the SFtX method. We find that, by adopting the mu(0) renormalization scale of Harlander et al. instead of the conventional mu(d) = 1/root 8t scale, the linear behavior at large flow-times is improved so that we can perform the t -> 0 extrapolation of the SFtX method more confidently. In the calculation of the two-loop matching coefficients by Harlander et al., the equation of motion for quark fields was used. For the entropy density in which the equation ofmotion has no effects, we find that the results using the two-loop coefficients agree well with those using one-loop coefficients. On the other hand, for the trace anomaly which is affected by the equation of motion, we find discrepancies between the one- and two-loop results at high temperatures. By comparing the results of one-loop coefficients with and without using the equation of motion, the main origin of the discrepancies is suggested to be attributed to contamination of O((aT)(2)) = O(1/N-t(2)) discretization errors in the equation of motion at N-t less than or similar to 10.

DOI： 10.1103/physrevd.102.014510

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その他リンク： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevD.102.014510/fulltext

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1103/PhysRevD.101.054505

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

© Copyright owned by the author(s) under the terms of the Creative Commons. In lattice QCD with Wilson-type quarks, the chiral symmetry is explicitly broken by the Wilson term on finite lattices. Though the symmetry is guaranteed to recover in the continuum limit, a series of non-trivial procedures are required to recover the correct renormalized theory in the continuum limit. Recently, a new use of the gradient flow technique was proposed, in which correctly renormalized quantities are evaluated in the vanishing flow-time limit. This enables us to directly study the chiral condensate and its susceptibility with Wilson-type quarks. Extending our previous study of the chiral condensate and its disconnected susceptibility in (2+1)-flavor QCD at a heavy u, d quark mass (mπ /mρ ≃ 0.63) and approximately physical s quark mass, we compute the connected contributions to the chiral susceptibility in the temperature range of 178–348 MeV on a fine lattice with a ≃ 0.07 fm.

DOI： 10.22323/1.334.0173

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

© Copyright owned by the author(s) under the terms of the Creative Commons. We study correlation functions of the energy-momentum tensor (EMT) in (2 + 1)-flavor full QCD to evaluate QGP viscosities. We adopt nonperturbatively improved Wilson fermion and Iwasaki gauge action. Our degenerate u, d quark mass is rather heavy with mπ /mρ ' 0.63, while the s quark mass is set to approximately its physical value. Performing simulations on lattices with Nt = 16 to 6 at a fine lattice spacing of a = 0.07 fm, the temperature range of T ' 174–464 MeV is covered using the fixed-scale approach. We attempt to compute viscosities by three steps: (1) calculate two point correlation functions of non-perturbatively renormalized EMT applying the gradient flow method, (2) derive the spectral function from correlation function, and (3) extract viscosities from the spectral function applying the Kubo formula. We report on the status of the project and present preliminary results for the shear viscosity in the high temperature phase.

DOI： 10.22323/1.334.0166

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

© Copyright owned by the author(s) under the terms of the Creative Commons. We study energy gap (latent heat) between the hot and cold phases at the first order phase transition point of the SU(3) gauge theory. Performing simulations on lattices with various spatial volumes and lattice spacings, we calculate the energy gap by a method using the Yang-Mills gradient flow and compare it with that by the conventional derivative method.

DOI： 10.22323/1.334.0164

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掲載種別：研究論文（学術雑誌）  

© 2019 authors. Published by the American Physical Society. Equation (C7) in the Appendix should read (Formula Presented) The wrong expression is not used in our numerical simulations and any results are not affected by this typo.

DOI： 10.1103/PhysRevD.99.059904

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

© The Authors, published by EDP Sciences, 2018. We study the energy-momentum tensor and the equation of state as well as the chiral condensate in (2+1)-flavor QCD at the physical point applying the method of Makino and Suzuki based on the gradient flow. We adopt a nonperturbatively O(a)- improved Wilson quark action and the renormalization group-improved Iwasaki gauge action. At Lattice 2016, we have presented our preliminary results of our study in (2+1)- flavor QCD at a heavy u; d quark mass point. We now extend the study to the physical point and perform finite-temperature simulations in the range T ? 155.544 MeV (Nt = 4-14 including odd Nt's) at a ? 0:09 fm. We show our final results of the heavy QCD study and present some preliminary results obtained at the physical point so far.

DOI： 10.1051/epjconf/201817507023

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

We measure correlation functions of the nonperturbatively renormalized
energy-momentum tensor in $N_f=2+1$ full QCD at finite temperature by applying
the gradient flow method both to the gauge and quark fields. Our main interest
is to study the conservation law of the energy-momentum tensor and to test
whether the linear response relation is properly realized for the entropy
density. By using the linear response relation we calculate the specific heat
from the correlation function. We adopt the nonperturbatively improved Wilson
fermion and Iwasaki gauge action at a fine lattice spacing $=0.07$ fm. In this
paper the temperature is limited to a single value $T=232$ MeV. The $u$, $d$
quark mass is rather heavy with $m_\pi/m_\rho=0.63$ while the $s$ quark mass is
set to approximately its physical value.

DOI： 10.1051/epjconf/201817507013

arXiv

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.256.0376

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

© Copyright owned by the author(s). The energy-momentum tensor and equation of state are studied in finite-temperature (2+1)-flavor QCD with improved Wilson quarks using the method proposed by Makino and Suzuki based on the gradient flow. We find that the results of the gradient flow are consistent with the previous results using the T-integration method at T <∼ 280MeV (Nτ > ∼ 10), while a disagreement is found at T > ∼ 350MeV (Nτ < ∼ 8) presumably due to the small-Nτ lattice artifact. We also report on the results on the renormalized chiral condensate and its disconnected susceptibility using the method of Hieda and Suzuki. The results show a clear signal of the expected chiral restoration crossover even with Wilson-type quarks which violate the chiral symmetry explicitly.

DOI： 10.22323/1.256.0063

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

© Copyright owned by the author(s). We study temperature dependence of the topological susceptibility with the Nf = 2+1 flavors Wilson fermion. We have two major interests in this paper. One is a comparison of gluonic and fermionic definitions of the topological susceptibility. Two definitions are related by the chiral Ward-Takahashi identity but their coincidence is highly non-trivial for the Wilson fermion. By applying the gradient flow both for the gauge and quark fields we find a good agreement of these two measurements. The other is a verification of a prediction of the dilute instanton gas approximation at low temperature region Tpc < T < 1.5Tpc, for which we confirm the prediction that the topological susceptibility decays with power χτ ∝ (T/Tpc)-8 for three flavors QCD.

DOI： 10.22323/1.256.0064

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

© Copyright owned by the author(s). We calculate the energy gap (latent heat) and pressure gap between the hot and cold phases of the SU(3) gauge theory at the first order deconfining phase transition point. We perform simulations around the phase transition point with the lattice size in the temporal direction Nτ =6; 8 and 12 and extrapolate the results to the continuum limit. The energy density and pressure are evaluated by the derivative method with nonperturabative anisotropy coefficients. We find that the pressure gap vanishes at all values of Nt. The spatial volume dependence in the latent heat is found to be small on large lattices. Performing extrapolation to the continuum limit, we obtain Δϵ=T4 =0:75±0:17 and δ(ϵ -3p)=T4 = 0:623±0:056: We also tested a method using the Yang-Mills gradient flow. The preliminary results are consistent with those by the derivative method within the error.

DOI： 10.22323/1.256.0058

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ELSEVIER SCIENCE BV  

Aiming to understand the phase structure of lattice QCD at nonzero temperature and density, we study the phase transitions of QCD in an extended parameter space, where the number of flavor and quark masses are considered as parameters. Performing simulations of 2 flavor QCD and using the reweighting method, we investigate (2 + N-f) flavor QCD at finite density, where two light flavors and N-f massive flavors exist. Calculating probability distribution functions, we determine the critical surface terminating first order phase transitions in the parameter space of the light quark mass, the heavy quark mass and the chemical potential. Through the study of the many flavor system, we discuss the phase structure of QCD at finite density.

DOI： 10.1016/j.nuclphysa.2016.01.030

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

The energy-momentum tensor plays an important role in QCD thermodynamics. Its
expectation value contains information of the pressure and the energy density
as its diagonal part. Further properties like viscosity and specific heat can
be extracted from its correlation function. Recently a new method based on the
gradient flow was introduced to calculate the energy-momentum tensor on the
lattice, and has been successfully applied to quenched QCD.
In this paper, we apply the gradient flow method to calculate the
energy-momentum tensor in (2+1)-flavor QCD. As the first application of the
method with dynamical quarks, we study at a single but fine lattice spacing
a=0.07 fm with heavy u and d quarks ($m_\pi/m_\rho=0.63$) and approximately
physical s quark. Performing simulations on lattices with Nt=16 to 4, the
temperature range of T=174-697 MeV is covered. We find that the results of the
pressure and the energy density by the gradient flow method are consistent with
the previous results using the T-integration method at T<280 MeV, while the
results show disagreement at T>350 MeV (Nt<8), presumably due to the small-Nt
lattice artifact of $O((aT)^2)=O(1/N_t^2)$.
We also apply the gradient flow method to evaluate the chiral condensate
taking advantage of the gradient flow method that renormalized quantities can
be directly computed avoiding the difficulty of explicit chiral violation with
lattice quarks. We compute the renormalized chiral condensate in the MS-bar
scheme at renormalization scale $\mu=2$ GeV with a high precision to study the
temperature dependence of the chiral condensate and its disconnected
susceptibility. Even with the Wilson-type quark action, we obtain the chiral
condensate and its disconnected susceptibility showing a clear signal of
pseudocritical temperature at T~190 MeV related to the chiral restoration
crossover.

DOI： 10.1103/PhysRevD.96.014509

arXiv

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

We discuss the importance of third moments of conserved charges around their averages in relativistic heavy-ion collisions.

DOI： 10.1140/epja/i2016-16252-5

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We calculate the energy gap (latent heat) and pressure gap between the hot and cold phases of the SU(3) gauge theory at the first order deconfining phase transition point. We perform simulations around the phase transition point with the lattice size in the temporal direction N-t = 6, 8 and 12 and extrapolate the results to the continuum limit. We also investigate the spatial volume dependence. The energy density and pressure are evaluated by the derivative method with nonperturabative anisotropy coefficients. We adopt a multipoint reweighting method to determine the anisotropy coefficients. We confirm that the anisotropy coefficients approach the perturbative values as N-t increases. We find that the pressure gap vanishes at all values of N-t when the nonperturbative anisotropy coefficients are used. The spatial volume dependence in the latent heat is found to be small on large lattices. Performing extrapolation to the continuum limit, we obtain Delta epsilon/T-4 = 0.75 +/- 0.17 and Delta(epsilon - 3p)/T-4 = 0.623 +/- 0.056.

DOI： 10.1103/PhysRevD.94.014506

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.251.0146

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.251.0150

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.251.0147

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.251.0209

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

Chiral phase transition of two-flavor QCD at finite quark masses is known to be a crossover except near the chiral limit, but it can turn to a first order transition when adding many extra flavors. This property is used to explore the nature of the phase transition of massless two-flavor QCD using lattice numerical simulations. The extra heavy flavors being incorporated in the form of the hopping parameter expansion through the reweighting, the number of the extra flavors and their masses appear only in a single parameter, defined by h. We determine the critical value of h, at which the first order and the crossover regions are separated, and examine its dependence on the two-flavor mass. The lattice calculations are carried out at N-t = 4, and show that the critical value of h does not depend on the two-flavor mass in the range we have studied (0.46 &lt;= m(pi)/m(rho) &lt;= 0.66) and appears to remain finite and positive in the chiral limit, suggesting that the phase transition of massless two-flavor QCD is of second order.

DOI： 10.1103/PhysRevD.93.054506

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.217.0014

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

The reweighting method is widely used in numerical studies of QCD, in particular, for the cases in which the conventional Monte Carlo method cannot be applied directly, e.g., finite density QCD. However, the application range of the reweighing method is restricted due to several problems. One of the most severe problems here is the overlap problem. To solve it, we examine a multipoint reweighting method in which simulations at several simulation points are combined in the data analyses. We systematically study the applicability and limitation of the multipoint reweighting method in two-flavor QCD at zero density. Measuring histograms of physical quantities at a series of simulation points, we apply the multipoint reweighting method to calculate the meson masses as continuous functions of the gauge coupling beta and the hopping parameters kappa. We then determine lines of constant physics and beta functions, which are needed in a calculation of the equation of state at finite temperature.

DOI： 10.1103/PhysRevD.92.094507

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.214.0222

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS INC  

Partition function zeros provide an alternative approach for studying the phase structure of finite density QCD. The structure of the Lee-Yang edge singularities associated with the zeros in the complex chemical potential plane has a strong influence on the real axis of the chemical potential. In order to investigate what the singularities are like in a concrete form, we resort to an effective theory based on a mean field approach in the vicinity of the critical point. The crossover is identified as a real part of the singular point. We consider the complex effective potential and explicitly study the behavior of its extrema in the complex order parameter plane in order to see how the Stokes lines are associated with the singularity. Susceptibilities in the complex plane are also discussed.

DOI： 10.1093/ptep/ptu108

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.187.0146

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.187.0450

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.187.0210

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We study the phase structure of lattice QCD with heavy quarks at finite temperature and density by a histogram method. We determine the location of the critical point at which the first-order deconfining transition in the heavy-quark limit turns into a crossover at intermediate quark masses through a change of the shape of the histogram under variation of coupling parameters. We estimate the effect of the complex phase factor, which causes the sign problem at finite density, and show that, in heavy-quark QCD, the effect is small around the critical point. We determine the critical surface in 2 + 1 flavor QCD in the heavy-quark region at all values of the chemical potential mu including mu = infinity.

DOI： 10.1103/PhysRevD.89.034507

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：World Scientific  

DOI： 10.1142/9789814566254_0005

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

We study the phase structure of QCD at high temperature and density by lattice QCD simulations adopting a histogram method. The quark mass dependence and the chemical potential dependence of the nature of phase transition are investigated focusing on the probability distribution function (histogram). The shape of the distribution function changes with the quark mass and chemical potential. Through the shape of the distribution, the critical surface which separates the first-order transition and crossover regions in the heavy quark region is determined for the (2+1)-flavor case. Moreover, we determined the critical point at finite density for two-flavor QCD with an intermediate quark mass, using a Gaussian approximation of the complex phase distribution of the quark determinant. The chemical potential dependence of the critical quark mass is also evaluated in the situation where two light quarks and many massive quarks exist. We find that the first-order transition region becomes wider with the chemical potential in the many-flavor QCD.

DOI： 10.1140/epja/i2013-13086-7

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Towards the feasibility study of the electroweak baryogenesis in realistic technicolor scenario, we investigate the phase structure of (2+N f)-flavor QCD, where the mass of two flavors is fixed to a small value and the others are heavy. For the baryogenesis, an appearance of a first-order phase transition at finite temperature is a necessary condition. Using a set of configurations of two-flavor lattice QCD and applying the reweighting method, the effective potential defined by the probability distribution function of the plaquette is calculated in the presence of additional many heavy flavors. Through the shape of the effective potential, we determine the critical mass of heavy flavors separating the first-order and crossover regions and find it to become larger with Nf. We moreover study the critical line at finite density and the first-order region is found to become wider as increasing the chemical potential. Possible applications to real (2+1)-flavor QCD are discussed. © 2013 American Physical Society.

DOI： 10.1103/PhysRevLett.110.172001

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.164.0074

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.164.0092

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.164.0089

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：VERSITA  

We study the QCD phase structure at high temperature and density adopting a histogram method. Because the quark determinant is complex at finite density, the Monte-Carlo method cannot be applied directly. We use a reweighting method and try to solve the problems which arise in the reweighting method, i.e. the sign problem and the overlap problem. We discuss the chemical potential dependence of the probability distribution function in the heavy quark mass region and examine the applicability of the approach in the light quark region.

DOI： 10.2478/s11534-012-0054-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

The free energies of static quarks and the Debye screening masses in the quark gluon plasma are studied using Polyakov-line correlation functions in lattice QCD adopting the fixed-scale approach in which temperature is varied without changing the spatial volume and the renormalization factors. We calculate static-quark free energies in various color channels in the high temperature phase up to about 3.5 times the (pseudo-)critical temperature, performing lattice simulations both in quenched and 2+1 flavor QCD. For the quenched simulations, we adopt the plaquette gauge action on anisotropic 20(3) x N-t lattices with N-t = 8-26 at the renormalized anisotropy a(s)/a(t) similar or equal to 4. For 2 + 1 flavor QCD, we adopt the renormalization-group improved Iwasaki gluon action and the non-perturbatively O(alpha)-improved Wilson quark action on isotropic 32(3) x N-t lattices with N-t = 4-12 at m(PS)/m(V) = 0.63 (0.74) for the light (strange) flavors. We find that the color-singlet free energies at high temperatures converge to the zero-temperature static-quark potential evaluated from the Wilson-loop at short distances. This is in accordance with the theoretical expectation that the short distance physics is insensitive to the temperature. At long distances, the free energies approach twice the single-quark free energies, implying that the interaction between static quarks is fully screened. We find that the static-quark free energies for various color channels turn out to be well described by the screened Coulomb form, and the color-channel dependence of the inter-quark interaction can be described by the kinetic Casimir factor inspired from the lowest order perturbation theory. We also discuss comparison with a prediction of the thermal perturbation theory and flavor dependence of the screening masses.

DOI： 10.1143/PTP.128.955

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.139.0214

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.139.0208

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We study the equation of state in 2 + 1 flavor QCD with nonperturbatively improved Wilson quarks coupled with the renormalization group-improved Iwasaki glue. We apply the T-integration method to nonperturbatively calculate the equation of state by the fixed-scale approach. With the fixed-scale approach, we can purely vary the temperature on a line of constant physics without changing the system size and renormalization constants. Unlike the conventional fixed-N-t approach, it is easy to keep scaling violations small at low temperature in the fixed-scale approach. We study 2 + 1 flavor QCD at light quark mass corresponding to m(pi)/m(rho) similar or equal to 0.63, while the strange quark mass is chosen around the physical point. Although the light quark masses are still heavier than the physical values, our equation of state is roughly consistent with recent results with highly improved staggered quarks at large N-t.

DOI： 10.1103/PhysRevD.85.094508

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society  

DOI： 10.1103/physrevd.85.079902

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その他リンク： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevD.85.079902/fulltext

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS INC  

The WHOT-QCD Collaboration is pushing forward a series of lattice studies of quantum chromodynamics (QCD) at finite temperatures and densities using improved Wilson quarks. Because Wilson-type quarks require more computational resources than the more widely used staggered-type quarks, various theoretical and computational techniques have to be developed and applied. In this paper, we introduce a fixed-scale approach armed with a T-integration method, a Gaussian method based on cumulant expansion, and a histogram method combined with the reweighting technique. Using these methods, we have carried out the first study of finite-density QCD with Wilson-type quarks and the first calculation of the equation of state with 2 + 1 flavors of Wilson-type quarks. We present the results of these studies and discuss perspectives towards clarification of the properties of 2 + 1 flavor QCD at the physical point at finite temperatures and densities.

DOI： 10.1093/ptep/pts005

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We propose a method to evaluate spectral functions on the lattice based on a variational method. On a lattice with a finite spatial extent, spectral functions consist of discrete spectra only. Adopting a variational method, we calculate the locations and the heights of spectral functions at low-lying discrete spectra. We first test the method in the case of analytically solvable free Wilson quarks at zero and finite temperatures and confirm that the method well reproduces the analytic results for low-lying spectra. We find that we can systematically improve the results by increasing the number of trial states. We then apply the method to calculate the charmonium spectral functions for S and P-wave states at zero-temperature in quenched QCD and compare the results with those obtained using the conventional maximum entropy method (MEM). The results for the ground state are consistent with the location and the area of the first peak in spectral functions from the MEM, while the variational method leads to a mass which is closer to the experimental value for the first excited state. We also investigate the temperature dependence of the spectral functions for S-wave states below and above T-c. We obtain no clear evidences for dissociation of J/Psi and eta(c) up to 1.4T(c).

DOI： 10.1103/PhysRevD.84.094504

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We study the quark mass dependence of the finite temperature QCD phase transition in the heavy quark region using an effective potential defined through the probability distribution function of the average plaquette. Performing a simulation of SU(3) pure gauge theory, we first confirm that the distribution function has two peaks indicating that the phase transition is of first order in the heavy quark limit, while the first-order transition turns into a crossover as the quark mass decreases from infinity, where the mass dependence of the distribution function is evaluated by the reweighting method combined with the hopping parameter expansion. We determine the endpoint of the first-order transition region for N(f) = 1, 2, 3 and 2 + 1 cases. The quark mass dependence of the latent heat is also evaluated in the first-order transition region.

DOI： 10.1103/PhysRevD.84.054502

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.105.0209

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.105.0212

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.105.0218

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.105.0181

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We study the equation of state at finite temperature and density in two-flavor QCD with the renormalization group improved gluon action and the clover-improved Wilson quark action on a 16(3) X 4 lattice. Along the lines of constant physics at m(PS)/m(V) = 0.65 and 0.80, we compute the second and forth derivatives of the grand canonical partition function with respect to the quark chemical potential mu(q) = (mu(u) + mu(d))/2 and the isospin chemical potential mu(I) = (mu(u) - mu(d))/2 at vanishing chemical potentials, and study the behaviors of thermodynamic quantities at finite mu(q) using these derivatives for the case mu(I) = 0. In particular, we study density fluctuations at nonezero temperature and density by calculating the quark number and isospin susceptibilities and their derivatives with respect to mu(q). To suppress statistical fluctuations, we also examine new techniques applicable at low densities. We find a large enhancement in the fluctuation of the quark number when the density increased near the pseudocritical temperature, suggesting a critical point at finite mu(q) terminating the first order transition line between hadronic and quark-gluon-plasma phases. This result agrees with the previous results using staggered-type quark actions qualitatively. Furthermore, we study heavy-quark free energies and Debye screening masses at finite density by measuring the first and second derivatives of these quantities for various color channels of heavy quark-quark and quark-antiquark pairs. The results suggest that, to the leading order of mu(q), the interaction between two quarks becomes stronger at finite densities, while that between quark and antiquark becomes weaker.

DOI： 10.1103/PhysRevD.82.014508

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.091.0190

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.091.0173

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.091.0174

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.091.0165

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

Screenings of the quark-gluon plasma in electric and magnetic sectors are studied on the basis of generalized Polyakov-line correlation functions in lattice QCD simulations with two flavors of improved Wilson quarks. Using the Euclidean-time reflection (R) and the charge conjugation (C), electric and magnetic screening masses are extracted in a gauge-invariant manner. Long distance behavior of the standard Polyakov-line correlation in the quark-gluon plasma is found to be dictated by the magnetic screening. Also, the ratio of the two screening masses agrees with that obtained from the dimensionally-reduced effective field theory and the N = 4 supersymmetric Yang-Mills theory.

DOI： 10.1103/PhysRevD.81.091501

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We calculate the QCD equation of state for temperatures corresponding to the transition region with physical mass values for two degenerate light quark flavors and a strange quark using an improved staggered fermion action (p4-action) on lattices with temporal extent N-tau = 8. We compare our results with previous calculations performed at twice larger values of the light quark masses as well as with results obtained from a resonance gas model calculation. We also discuss the deconfining and chiral aspects of the QCD transition in terms of renormalized Polyakov loop, strangeness fluctuations, and subtracted chiral condensate. We show that compared to the calculations performed at twice larger value of the light quark mass the transition region shifts by about 5 MeV toward smaller temperatures.

DOI： 10.1103/PhysRevD.81.054504

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We study the phase structure of QCD at finite temperature and density by numerical simulations on a lattice. The most important point for the numerical study at finite density is treatment of the sign problem. We propose a method to avoid the sign problem, which is based on a cumulant expansion of the complex phase in the density of state method combined with the reweighting method. Using the method, we study the critical point terminating a first order phase transition line in lattice QCD at high temperature and density.

DOI： 10.1143/PTPS.186.510

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

The WHOT-QCD Collaboration is pushing forward lattice studies of QCD at finite temperatures and densities using improved Wilson quarks. We first present results on QCD at zero and finite densities with two flavors of degenerate quarks (N(F) = 2 QCD) adopting the conventional fixed-N(t) approach. We then report on the status of a study of N(F) = 2 + 1 QCD adopting a fixed-scale approach armed with the T-integration method which we have developed.

DOI： 10.1143/PTPS.186.556

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

The third moments of conserved charges, the baryon and electric charge numbers, and energy, as well as their mixed moments, carry more information on the state around the QCD phase boundary than previously proposed fluctuation observables and higher order moments. In particular, their signs give plenty of information on the location of the state created in relativistic heavy ion collisions in the temperature and baryon chemical potential plane. We demonstrate this with an effective model.

DOI： 10.1103/PhysRevLett.103.262301

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1016/j.nuclphysa.2009.10.155

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We propose a fixed scale approach to calculate the equation of state (EOS) in lattice QCD. In this approach, the temperature T is varied by N(t) at fixed lattice spacings. This enables us to reduce T = 0 simulations which are required to provide basic data in finite temperature studies but are quite expensive in the conventional fixed-N(t) approach. Since the conventional integral method to obtain the pressure is inapplicable at fixed scale, we introduce a new method, "T-integration method", to calculate pressure non-perturbatively. We test the fixed scale approach armed with the T-integral method in quenched QCD on isotropic and anisotropic lattices. Our method is found to be powerful to obtain reliable results for the equation of state, especially at intermediate and low temperatures. Reduction of the computational cost of T = 0 simulations is indispensable to study EOS in QCD with dynamical quarks. The status of our study in N(f) = 2 + 1 QCD with improved Wilson quarks is also reported.

DOI： 10.1016/j.nuclphysa.2009.10.004

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The free energy between a static quark and an antiquark is studied by using the color-singlet Polyakov-line correlation at finite temperature in lattice QCD with 2+1 flavors of improved Wilson quarks. From the simulations on 32(3) X 12, 10, 8, 6, 4 lattices in the high temperature phase, based on the fixed scale approach, we find that, the heavy-quark free energies at short distance converge to the heavy-quark potential evaluated from the Wilson loop at zero temperature, in accordance with the expected insensitivity of short distance physics to the temperature. At long distance, the heavy-quark free energies approach to twice the single-quark free energies, implying that the interaction between heavy quarks is screened. The Debye screening mass obtained from the long range behavior of the free energy is compared with the results of thermal perturbation theory.

DOI： 10.1016/j.nuclphysa.2009.10.021

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

A first study of critical behavior in the vicinity of the chiral phase transition of (2+1)-flavor QCD is presented. We analyze the quark mass and volume dependence of the chiral condensate and chiral susceptibilities in QCD with two degenerate light quark masses and a strange quark. The strange quark mass (m(s)) is chosen close to its physical value; the two degenerate light quark masses (m(l)) are varied in a wide range 1/80 &lt; m(l)/m(s)&lt; 2/5, where the smallest light quark mass value corresponds to a pseudoscalar Goldstone mass of about 75 MeV. All calculations are performed with staggered fermions on lattices with temporal extent N-tau=4. We show that numerical results are consistent with O(N) scaling in the chiral limit. We find that in the region of physical light quark mass values, m(l)/m(s)similar or equal to 1/20, the temperature and quark mass dependence of the chiral condensate is already dominated by universal properties of QCD that are encoded in the scaling function for the chiral order parameter, the magnetic equation of state. We also provide evidence for the influence of thermal fluctuations of Goldstone modes on the chiral condensate at finite temperature. At temperatures below, but close to the chiral phase transition at vanishing quark mass, this leads to a characteristic dependence of the light quark chiral condensate on the square root of the light quark mass.

DOI： 10.1103/PhysRevD.80.094505

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We propose a method to find the QCD critical point at finite density calculating the canonical partition function Z(C)(T, N) by Monte-Carlo simulations of lattice QCD, and analyze data obtained by a simulation with two-flavor p4-improved staggered quarks with pion mass m(pi) approximate to 770MeV. It is found that the shape of an effective potential changes gradually as the temperature decreases and a first order phase transition appears in the low temperature and high density region. This result strongly Suggests the existence of the critical point in the (T, mu(q)) phase diagram.

DOI： 10.1016/j.nuclphysa.2009.09.060

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We calculate the equation of state in 2+1 flavor QCD at finite temperature with physical strange quark mass and almost physical light quark masses using lattices with temporal extent N(tau)=8. Calculations have been performed with two different improved staggered fermion actions, the asqtad and p4 actions. Overall, we find good agreement between results obtained with these two O(a(2)) improved staggered fermion discretization schemes. A comparison with earlier calculations on coarser lattices is performed to quantify systematic errors in current studies of the equation of state. We also present results for observables that are sensitive to deconfining and chiral aspects of the QCD transition on N(tau)=6 and 8 lattices. We find that deconfinement and chiral symmetry restoration happen in the same narrow temperature interval. In an appendix we present a simple parametrization of the equation of state that can easily be used in hydrodynamic model calculations. In this parametrization we include an estimate of current uncertainties in the lattice calculations which arise from cutoff and quark mass effects.

DOI： 10.1103/PhysRevD.80.014504

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.066.0002

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.066.0194

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.066.0189

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.066.0174

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

A new approach to study the equation of state in finite-temperature QCD is proposed on the lattice. Unlike the conventional method in which the temporal lattice size N(t) is fixed, the temperature T is varied by changing N(t) at the fixed lattice scale. The pressure of the hot QCD plasma is calculated by the integration of the trace anomaly with respect to T at the fixed lattice scale. This "T-integral method&apos;&apos; is tested in quenched QCD on isotropic and anisotropic lattices and is shown to give reliable results, especially at intermediate and low temperatures.

DOI： 10.1103/PhysRevD.79.051501

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We discuss the nature of the phase transition for lattice QCD at finite temperature and density. We propose a method to calculate the canonical partition function by fixing the total quark number introducing approximations allowed in the low density region. An effective potential as a function of the quark number density is discussed from the canonical partition function. We analyze data obtained in a simulation of two-flavor QCD using p4-improved staggered quarks with bare quark mass m/T=0.4 on a 16(3)x4 lattice. The results suggest that the finite density phase transition at low temperature is of first order.

DOI： 10.1103/PhysRevD.78.074507

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.042.0181

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.042.0207

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We propose a method to probe the nature of phase transitions in lattice QCD at finite temperature and density, which is based on the investigation of an effective potential as a function of the average plaquette. We analyze data obtained in a simulation of two-flavor QCD using p4-improved staggered quarks with bare quark mass m/T=0.4 and find that a first order phase transition line appears in the high density regime for mu(q)/T greater than or similar to 2.5. We also discuss the difference between the phase structures of QCD with nonzero quark chemical potential and nonzero isospin chemical potential.

DOI： 10.1103/PhysRevD.77.014508

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

We report the current status of our systematic studies of the QCD thermodynamics by lattice QCD simulations with two flavours of improved Wilson quarks. We evaluate the critical temperature of two-flavour QCD in the chiral limit at a zero chemical potential and show the preliminary result. Also we discuss fluctuations at non-zero temperature and density by calculating the quark number and isospin susceptibilities and their derivatives with respect to the chemical potential. © 2007 IOP Publishing Ltd.

DOI： 10.1088/0954-3899/34/8/S65

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We study Polyakov loop correlations and spatial Wilson loop at finite temperature in two-flavor QCD simulations with the RG-improved gluon action and the clover-improved Wilson quark action on a 16(3)x4 lattice. From the line of constant physics at m(PS)/m(V)=0.65 and 0.80, we extract the heavy-quark free energies, the effective running coupling g(eff)(T) and the Debye screening mass m(D)(T) for various color channels of heavy quark-quark and quark-antiquark pairs above the critical temperature. The free energies are well approximated by the screened Coulomb form with the appropriate Casimir factors at high temperature. The magnitude and the temperature dependence of the Debye mass are compared to those of the next-to-leading-order thermal perturbation theory and to a phenomenological formula in terms of g(eff)(T). We make a comparison between our results with the Wilson quark action and the previous results with the staggered quark action. The spatial string tension is also studied in the high temperature phase and is compared to the next-to-next-leading-order prediction in an effective theory with dimensional reduction.

DOI： 10.1103/PhysRevD.75.074501

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We review studies of QCD thermodynamics by lattice QCD simulations with dynamical Wilson quarks. After explaining the basic properties of QCD with Wilson quarks at finite temperature including the phase structure and the scaling properties around the chiral phase transition, we discuss the critical temperature, the equation of state and heavy-quark free energies.

DOI： 10.1143/PTPS.168.245

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.032.0132

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.032.0150

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.032.0141

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We analyze fluctuations of quark number and electric charge, in 2-flavour QCD at finite temperature and vanishing net baryon number density. In the hadronic phase we find that an enhancement of charge fluctuations arises from contributions of doubly charged hadrons to the thermodynamics. The rapid suppression of fluctuations seen in the high temperature phase suggests that in the QGP quark number and electric charge are predominantly carried by quasi-particles with the quantum numbers of quarks.

DOI： 10.1016/j.nuclphysa.2006.06.099

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present results of a simulation of 2 flavour QCD on a 16(3) x 4 lattice using p4-improved staggered fermions with bare quark mass m/T = 0.4. Derivatives of the thermodynamic grand canonical partition function Z(V,T,mu(mu,) mu(d)) with respect to chemical potentials mu(mu,d) for different quark flavours are calculated up to sixth order, enabling estimates of the pressure and the quark number density as well as the chiral condensate and various susceptibilities as functions Of mu(mu,d) via Taylor series expansion. Results are compared to high temperature perturbation theory as well as a hadron resonance gas model. We also analyze baryon as well as isospin fluctuations and discuss the relation to the chiral critical point in the QCD phase diagram. We moreover discuss the dependence of the heavy quark free energy on the chemical potential.

DOI： 10.1016/j.nuclphysa.2006.06.023

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

We analyze the dependence of heavy quark free energies on the baryon chemical potential mu(b) in 2-flavor QCD by performing a 6th order Taylor expansion in the chemical potential which circumvents the sign problem. The bare quark mass at (m) over cap /T = 0.4 corresponds to a pion mass of about 770 MeV and is thus not in the range of physical quark masses but the quark mass dependence is known. to be small above T-c. At N-tau = 4 the lattices are coarse, however, we are using improved (p4 staggered) fermions. The Taylor expansion coefficients of color singlet and color averaged free energies are calculated and from this the expansion coefficients for the corresponding screening masses are determined. We find that for small mu(b) the free energies of a static quark-antiquark pair decrease in a medium with a net excess of quarks and that screening is well described by a screening mass which increases with increasing mu(b). The mu(b)-dependent corrections to the screening masses are well described by perturbation theory for T greater than or similar to 2T(c). In particular, we find for all temperatures above T. that the expansion coefficients for singlet and color averaged screening masses differ by a factor 2.

DOI： 10.1140/epjc/s2005-02462-y

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We comment on the Lee-Yang zero analysis for the study of the phase structure of QCD at high temperature and baryon number density by Monte-Carlo simulations. We find that the sign problem for nonzero density QCD induces a serious problem in the finite volume scaling analysis of the Lee-Yang zeros for the investigation of the order of the phase transition. If the sign problem occurs at large volume, the Lee-Yang zeros will always approach the real axis of the complex parameter plane in the thermodynamic limit. This implies that a scaling behavior which would suggest a crossover transition will not be obtained. To clarify this problem, we discuss the Lee-Yang zero analysis for SU(3) pure gauge theory as a simple example without the sign problem, and then consider the case of nonzero density QCD. It is suggested that the distribution of the Lee-Yang zeros in the complex parameter space obtained by each simulation could be more important information for the investigation of the critical endpoint in the (T,mu(q)) plane than the finite volume scaling behavior.

DOI： 10.1103/PhysRevD.73.054502

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

Using Taylor expansions of the pressure obtained previously in studies of 2-flavor QCD at nonzero chemical potential we calculate expansion coefficients for the energy and entropy densities up to O(mu(6)(q)) in the quark chemical potential. We use these series in mu(q)/T to determine lines of constant entropy per baryon number (S/N-B) that characterize the expansion of dense matter created in heavy ion collisions. In the high temperature regime these lines are found to be well approximated by lines of constant mu(q)/T. In the low temperature phase, however, the quark chemical potential is found to increase with decreasing temperature. This is in accordance with resonance gas model calculations. Along the lines of constant S/N-B we calculate the energy density and pressure. Within the accuracy of our present analysis we find that the ratio p/epsilon for T &gt; T-0 as well as the softest point of the equation of state, (p/epsilon)(min)similar or equal to 0.075, show no significant dependence on S/N-B.

DOI： 10.1103/PhysRevD.73.054506

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We discuss the properties of hadronic fluctuations, i.e., fluctuations of net quark and isospin numbers as well as electric charge, in the vicinity of the QCD transition in isospin-symmetric matter at vanishing quark chemical potential. We analyse second-and fourth-order cumulants of these fluctuations and argue that the ratio of quartic and quadratic cumulants reflects the relevant degrees of freedom that carry the quark number, isospin or charge, respectively. In the hadronic phase we find that an enhancement of charge fluctuations arises from contributions of doubly charged hadrons to the thermodynamics. The rapid suppression of fluctuations seen in the high-temperature phase suggests that in the QGP, net quark number and electric charge are predominantly carried by quasi-particles, with the quantum numbers of quarks. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physletb.2005.11.083

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.020.0193

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.22323/1.020.0183

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The study of systems as diverse as the cores of neutron stars and heavy-ion collision experiments requires the understanding of the phase structure of QCD at non-zero temperature, T, and chemical potential, mu(q). We review some of the difficulties of performing lattice simulations of QCD with mu(q) not equal 0, and outline the re-weighting method used to overcome this problem. This method is used to determine the critical endpoint of QCD in the (mu(q), T) plane. We study the pressure and quark number susceptibility at small mu(q).

DOI： 10.1016/j.nuclphysbps.2004.12.028

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We present results of a simulation of two flavor QCD on a 16(3) X 4 lattice using p4-improved staggered fermions with bare quark mass m/T = 0.4. Derivatives of the thermodynamic grand canonical partition function Z(V, T, mu(mu), mu(d)) with respect to chemical potentials mu(mu,d) for different quark flavors are calculated up to sixth order, enabling estimates of the pressure and the quark number density as well as the chiral condensate and various susceptibilities as functions of mu(q) = (mu(mu) + mu(d))/2 via Taylor series expansion. Furthermore, we analyze baryon as well as isospin fluctuations and discuss the relation between the radius of convergence of the Taylor series and the chiral critical point in the QCD phase diagram. We argue that bulk thermodynamic observables do not, at present, provide direct evidence for the existence of a chiral critical point in the QCD phase diagram. Results are compared to high temperature perturbation theory as well as a hadron resonance gas model.

DOI： 10.1103/PhysRevD.71.054508

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We study the susceptibilities of quark number, isospin number and electric charge in numerical simulations of lattice QCD at high temperature and density. We discuss the equation of state for 2 flavor QCD at non-zero temperature and density. Derivatives of In Z with respect to quark chemical potential (mu(q)) are calculated up to sixth order. From this Taylor series, the susceptibilities are estimated as functions of temperature and mu(q). Moreover, we comment on the hadron resonance gas model, which explains well our simulation results below T-c.

DOI： 10.1016/j.nuclphysbps.2004.11.336

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：WORLD SCIENTIFIC PUBL CO PTE LTD  

We discuss the equation of state (EoS) for two flavor QCD at non-zero temperature and density. Derivatives of In Z with respect to quark chemical potential mu(q) are calculated up to sixth order. From this Taylor series, the pressure, quark number density and associated susceptibilities are estimated as functions of temperature and mu(q). It is found that the fluctuations in the quark number density increase in the vicinity of the phase transition temperature and the susceptibilities start to develop a pronounced peak as mu(q) is increased. This suggests the presence of a critical endpoint in the (mu(q), T) plane. Moreover, we comment on the hadron resonance gas model, which explains well our simulation results below T-c.

DOI： 10.1142/9789812702159_0050

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We present results of a simulation of QCD on a 16(3)x4 lattice with 2 continuum flavors of a p4-improved staggered fermion with mass m/T = 0.4. Derivatives of the thermodynamic grand potential Omega with respect to the quark chemical potential mu(q) up to fourth order are calculated, enabling estimates of the pressure, quark number density and associated susceptibilities as functions of mu(q) via Taylor series expansion. Discretization effects associated with various staggered fermion formulations are discussed in some detail. In addition it is possible to estimate the radius of convergence of the expansion as a function of temperature. We also discuss the calculation of energy and entropy densities which are defined via mixed derivatives of Omega with respect to the bare couplings and quark masses.

DOI： 10.1103/PhysRevD.68.014507

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We comment on the reweighting method for the study of finite density lattice QCD. We discuss the applicable parameter range of the reweighting method for models that have more than one simulation parameter. The applicability range is determined by the fluctuations of the modification factor of the Boltzmann weight. In some models having a first order phase transition, the fluctuations are minimized along the phase transition line if we assume that the pressure in the hot and the cold phases is balanced at the first order phase transition point. This suggests that the reweighting method with two parameters is applicable in a wide range for the purpose of tracing out the phase transition line in the parameter space. To confirm the usefulness of the reweighting method for two-flavor QCD, the fluctuations of the reweighting factor are measured by numerical simulations for the cases of reweighting in the quark mass and chemical potential directions. The relation to the phase transition line is discussed. Moreover, the sign problem caused by the complex phase fluctuations is studied.

DOI： 10.1103/PhysRevD.69.094506

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：WORLD SCIENTIFIC PUBL CO PTE LTD  

We discuss the equation of state for 2 flavor QCD at non-zero temperature and density. Derivatives of In Z with respect to quark chemical potential mu(q) up to fourth order are calculated, enabling estimates of the pressure, quark number density and associated susceptibilities as functions Of mu(q) via a Taylor series expansion. It is found that the fluctuations in the quark number density increase in the vicinity of the phase transition temperature and the susceptibilities start to develop a pronounced peak as p. is increased. This suggests the presence of a critical endpoint in the (T, mu(q)) plane.

DOI： 10.1142/9789812702845_0034

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We discuss the equation of state for QCD at non-zero temperature and density. We present, results of a simulation for QCD with 2 flavors of p4-improved staggered fermions. Derivatives of In Z with respect to quark chemical potential mu(q) up to fourth order are calculated, enabling estimates of the pressure, quark number density and associated susceptibilities as functions of mu(q) via a Taylor series expansion. We also discuss the radius of convergence of the expansion as a function of temperature. It, is found that the fluctuations in the quark number density increase in the vicinity of the phase transition temperature and the susceptibilities start to develop a pronounced peak as mu(q), is increased. This suggest's the presence of a critical endpoint in the (T, mu(q)) plane.

DOI： 10.1016/j.nuclphysbps.2003.12.213

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We determine the location of the second order endpoint of the line of first order chiral phase transition in 3-flavor QCD at vanishing chemical potential (mu(q)). Using Ferrenberg-Swendsen reweighting for two values of the quark mass we determine the mu(q)-dependence of the transition line and locate the chiral critical point. For both quantities we find a significant quark mass dependence.

DOI： 10.1016/j.nuclphysbps.2003.12.236

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We study the renormalized free energy of a heavy quark anti-quark pair in the different colour channels in full QCD at finite temperature. Similarities and differences to the quenched case are discussed and the temperature dependence as well as their short distance behavior are analyzed. The asymptotic large distance behavior of the free energy is used to define the non-perturbatively renormalized Polyakov loop which is well behaved in the continuum limit.

DOI： 10.1143/PTPS.153.287

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We report on the status of our simulations of two-colour QCD with two flavours of Wilson quarks, at nonzero chemical potential and diquark source. Preliminary results are presented for the static quark potential, gluon propagator, and meson and diquark spectrum.

DOI： 10.1143/PTPS.153.60

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We discuss the phase structure and the equation of state for QCD at non-zero temperature and density. Derivatives of ln Z with respect to quark chemical potential mu(q) up to fourth order are calculated for 2-flavor QCD, enabling estimates of the pressure, quark number density and associated susceptibilities as functions of mu(q) via a Taylor series expansion. Also, the phase transition line for 2 and 3-flavor QCD and the critical endpoint in the (T, mu(q)) plane are investigated in the low density regime.

DOI： 10.1143/PTPS.153.118

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We explore the application of the domain wall fermion formalism of lattice QCD to calculate the K--&gt;pipi decay amplitudes in terms of the K+--&gt;pi(+) and K-0--&gt;0 hadronic matrix elements through relations derived in chiral perturbation theory. Numerical simulations are carried out in quenched QCD using the domain-wall fermion action for quarks and a renormalization group-improved gauge action for gluons on a 16(3)x32x16 and 24(3)x32x16 lattice at beta = 2.6 corresponding to the lattice spacing 1/a approximate to 2 GeV. Quark loop contractions which appear in Penguin diagrams are calculated by the random noise method, and the DeltaI = 1/2 matrix elements which require subtractions with the quark loop contractions are obtained with a statistical accuracy of about 10%. We investigate the chiral properties required of the K+--&gt;pi(+) matrix elements. Matching the lattice matrix elements to those in the continuum at mu = 1/a using the perturbative renormalization factor to one loop order, and running to the scale mu = m(c) = 1.3 GeV with the renormalization group for N-f = 3 flavors, we calculate all the matrix elements needed for the decay amplitudes. With these matrix elements, the DeltaI = 3/2 decay amplitude Re A(2) shows a good agreement with experiment after an extrapolation to the chiral limit. The DeltaI = 1/2 amplitude Re A(0), on the other hand, is about 50-60 % of the experimental one even after chiral extrapolation. In view of the insufficient enhancement of the DeltaI = 1/2 contribution, we employ the experimental values for the real parts of the decay amplitudes in our calculation of epsilon'/epsilon. The central values of our result indicate that the DeltaI = 3/2 contribution is larger than the DeltaI = 1/2 contribution so that epsilon'/epsilon is negative and has a magnitude of order 10(-4). We discuss in detail possible systematic uncertainties, which seem too large for a definite conclusion on the value of epsilon'/epsilon.

DOI： 10.1103/PhysRevD.68.014501

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We study a block spin transformation in the SU(3) lattice gauge theory on anisotropic lattices to obtain Iwasaki's renormalization-group-improved action for anisotropic cases. For the class of actions with plaquette and 1x2 rectangular terms, we determine the improvement parameters as functions of the anisotropy xi = a(s)/a(t). We find that the program of improvement works well also on anisotropic lattices. From a study of an indicator which estimates the distance to the renormalized trajectory, we show that, for the range of the anisotropy xi approximate to 1-4, the coupling parameters previously determined for isotropic lattices improve the theory considerably.

DOI： 10.1103/PhysRevD.68.014502

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：WORLD SCIENTIFIC PUBL CO PTE LTD  

We comment on the reweighting method in the chemical potential (mu(q)) direction. We study the fluctuation of the reweighting factor during Monte-Carlo steps. We find that it is the absolute value of the reweighting factor that mainly contributes to the shift of the phase transition line (beta(c)) by the presence of mu(q). The phase fluctuation is a cause of the sign problem, but the effect on beta(c) seems to be small. We also discuss beta(c), for lso-vector chemical potential and beta(c), determined from simulations with imaginary chemical potential.

DOI： 10.1142/9789812704498_0025

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

In order to study the QCD chiral critical point we investigate Binder Cumulants of the chiral condensate. The results were obtained from simulations of 3 and 2+1 flavors of standard staggered fermions and 3 flavors of p4 improved staggered fermions. The quark masses used are close to the physical quark mass. To extract the dependence on quark mass and chemical potential we apply a new reweighting technique based on a Taylor expansion of the action. The reweighting accuracy is 0(m) for the standard and O(m(2)), O(mu(2)) for the p4 action.

DOI： 10.1016/S0920-5632(03)01601-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We study the thermal properties of QCD in the presence of a small quark chemical potential p. Derivatives of the phase transition point with respect to mu axe computed at mu = 0 for 2 and 3 flavors of p-4 improved staggered fermions on a 16(3) x 4 lattice. Moreover we contrast the case of isoscalar and isovector chemical potentials, quantify the effect of mu not equal 0 on the equation of state, and comment on the screening effect by dynamical quarks and the complex phase of the fermion determinant in QCD with mu not equal 0.

DOI： 10.1016/S0920-5632(03)01613-X

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掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society (APS)  

DOI： 10.1103/physrevd.67.059901

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その他リンク： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevD.67.059901/fulltext

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We present the details of simulations for the light hadron spectrum in quenched QCD carried out on the CP-PACS parallel computer. Simulations are made with the Wilson quark action and the plaquette gauge action on lattices of size 32(3)x56-64(3)x112 at four values of lattice spacings in the range aapproximate to0.1-0.05 fm and spatial extent L(s)aapproximate to3 fm. Hadronic observables are calculated at five quark masses corresponding to m(PS)/m(V)approximate to0.75-0.4, assuming the u and d quarks are degenerate, but treating the s quark separately. We find that the presence of quenched chiral singularities is supported from an analysis of the pseudoscalar meson data. The physical values of hadron masses are determined using m(pi), m(rho), and m(K) (or m(phi)) as input to fix the physical scale of lattice spacing and the u, d, and s quark masses. After chiral and continuum extrapolations, the agreement of the calculated mass spectrum with experiment is at a 10% level. In comparison with the statistical accuracy of 1%-3% and systematic errors of at most 1.7% we have achieved, this demonstrates a failure of the quenched approximation for the hadron spectrum: the hyperfine splitting in the meson sector is too small, and in the baryon sector the octet masses and mass splitting of the decuplet are both smaller than experiment. Light quark masses are calculated using two definitions: the conventional one and the one based on the axial-vector Ward identity. The two results converge toward the continuum limit, yielding m(ud)=4.29(14)(-0.79)(+0.51) MeV where the first error is statistical and the second one is systematic due to chiral extrapolation. The s quark mass depends on the strange hadron mass chosen for input: m(s)=113.8(2.3)(-2.9)(+5.8) MeV from m(K) and m(s)=142.3(5.8)(-0)(+22.0) MeV from m(phi), indicating again a failure of the quenched approximation. We obtain the scale of QCD, Lambda((M) over bar)((0))=219.5(5.4) MeV with m(rho) used as input. An O(10%) deviation from experiment is observed in the pseudoscalar meson decay constants.

DOI： 10.1103/PhysRevD.67.034503

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society (APS)  

DOI： 10.1103/physrevlett.90.029902

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その他リンク： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.90.029902/fulltext

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMERICAN PHYSICAL SOC  

We propose a new method to investigate the thermal properties of QCD with a small quark chemical potential mu. Derivatives of quark and gluonic observables with respect to mu are computed at mu=0 for two flavors of p4 improved staggered fermions with ma=0.1,0.2 on a 16(3)x4 lattice, and used to calculate the leading order Taylor expansion in mu of the location of the pseudocritical point about mu=0. This expansion should be well behaved for the small values of mu(q)/T(c)similar to0.1 relevant for BNL RHIC phenomenology, and predicts a critical curve T-c(mu) in reasonable agreement with estimates obtained using exact reweighting. In addition, we contrast the case of isoscalar and isovector chemical potentials, quantify the effect of munot equal0 on the equation of state, and comment on the complex phase of the fermion determinant in QCD with munot equal0.

DOI： 10.1103/PhysRevD.66.074507

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society (APS)  

Monte Carlo simulations are performed in a five-dimensional lattice SU(2) Yang-Mills theory with a compactified extra dimension, and scaling laws are studied. Our simulations indicate that, as the compactification radius R decreases, the confining phase spreads more and more to the weak coupling regime, and the effective dimension of the theory changes gradually from five to four. Our simulations also indicate that the limit a(4)--&gt;0 with R/a(4) kept fixed exists in both the confining and deconfining phases if R/a(4) is small enough, where a(4) is the lattice spacing in the four-dimensional direction. We argue that there exists a maximal radius above which the color degrees of freedom are not confined. Comments on deconstructing extra dimensions are given.

DOI： 10.1103/physrevd.66.036002

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その他リンク： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevD.66.036002/fulltext

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We present a detailed study of the charmonium spectrum using anisotropic lattice QCD. We first derive a tree-level improved clover quark action on the anisotropic lattice for arbitrary quark mass by matching the Hamiltonian on the lattice and in the continuum. The heavy quark mass dependence of the improvement coefficients, i.e., the ratio of the hopping parameters zeta=K-t/K-s and the clover coefficients c(s,t), is examined at the tree level, and effects of the choice of the spatial Wilson parameter r(s) are discussed. We then compute the charmonium spectrum in the quenched approximation employing xi=a(s)/a(t)=3 anisotropic lattices. Simulations are made with the standard anisotropic gauge action and the anisotropic clover quark action with r(s)=1 at four lattice spacings in the range a(s)=0.07-0.2 fm. The clover coefficients c(s,t) are estimated from tree-level tadpole improvement. On the other hand, for the ratio of the hopping parameters zeta, we adopt both the tree-level tadpole-improved value and a non-perturbative one. The latter employs the condition that the speed of light calculated from the meson energy-momentum relation be unity. We calculate the spectrum of S and P states and their excitations using both the pole and kinetic masses. We find that the combination of the pole mass and the tadpole-improved value of zeta to yield the smoothest approach to the continuum limit, which we then adopt for the continuum extrapolation of the spectrum. The results largely depend on the scale input even in the continuum limit, showing a quenching effect. When the lattice spacing is determined from the 1P-1S splitting, the deviation from the experimental value is estimated to be similar to30% for the S-state hyperfine splitting and similar to20% for the P-state fine structure. Our results are consistent with previous results at xi=2 obtained by Chen when the lattice spacing is determined from the Sommer scale r(0). We also address the problem with the hyperfine splitting that different choices of the clover coefficients lead to disagreeing results in the continuum limit. Making a leading order analysis based on potential models we show that a large hyperfine splitting similar to95 MeV obtained by Klassen with a different choice of the clover coefficients is likely an overestimate.

DOI： 10.1103/PhysRevD.65.094508

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1142/9789812776662_0015

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

we present a calculation of the K --&gt; pipi decay amplitudes from the K --&gt; pi matrix elements using leading order relations derived in chiral perturbation theory. Numerical simulations are carried out in quenched QCD with the domain-wall fermion action and the renormalization group improved gluon action. Our results show that the I = 2 amplitude is reasonably consistent with experiment whereas the I = 0 amplitude is sizably smaller. Consequently the DeltaI = 1/2 enhancement is only half of the experimental value, and epsilon'/epsilon is negative.

DOI： 10.1016/S0920-5632(01)01705-4

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/S0920-5632(01)01862-X

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present results for the equation of state for pure SU(3) gauge theory obtained on anisotropic lattices with the anisotropy xi equivalent to a(s)/a(t) = 2. The pressure and energy density are calculated on N-t/xi = 4,5 and 6 lattices with the integral method. They are found to satisfy the leading 1/N-t(2) scaling from our coarsest lattice N-t/xi = 4. This enables us to carry out well controlled continuum extrapolations. We find that the pressure and energy density agree with those obtained using the isotropic plaquette action, but have smaller and more reliable errors.

DOI： 10.1016/S0920-5632(01)01752-2

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We propose a new method to investigate the thermal properties of QCD with a small chemical potential (mu). The derivatives of the phase transition point with respect to a are computed for 2 flavors of p4-improved staggered fermions. We moreover comment on the complex phase of the fermion determinant in finite-density QCD.

DOI： 10.1016/S0920-5632(01)01746-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present our final results of the charmonium spectrum in quenched QCD on anisotropic lattices. Simulations are made with the plaquette gauge action and a tadpole improved clover quark action employing xi = a(3)/a(t) = 3. We calculate the spectrum of S- and P-states and their excitation, and study the scaling behavior of mass splittings. Comparison is made with the experiment and previous lattice results. The issue of hyperfine splitting for different choices of the clover coefficients obtained by Klassen is discussed.

DOI： 10.1016/S0920-5632(01)01715-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We investigate a chiral property of the domain-wall fermion (DWF) system using the four-dimensional hermitian Wilson-Dirac operator H-W. A formula expressing the Ward-Takahashi identity quark mass m(5q) with eigenvalues of this operator is derived, which well explains the N-5 dependence of m(5q) observed in previous numerical simulations. We further discuss the chiral property of DWF in the large volume in terms of the spectra of H-W.

DOI： 10.1016/S0920-5632(01)01826-6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We present results of a numerical calculation of lattice QCD with two degenerate flavors of dynamical quarks, identified with up and down quarks, and with a strange quark treated in the quenched approximation. The lattice action and simulation parameters are chosen with a view to carrying out an extrapolation to the continuum limit as well as chiral extrapolations in dynamical up and down quark masses. Gauge configurations are generated with a renormalization-group improved gauge action and a mean field improved clover quark action at three values of beta = 6/g(2), corresponding to lattice spacings of aapproximate to0.22, 0.16 and 0.11 fm, and four sea quark masses corresponding to m(PS)/m(V)approximate to0.8, 0.75, 0.7 and 0.6. The sizes of lattice are chosen to be 123 x 24, 16(3) x 32 and 24(3) x 48 so that the physical spatial size is kept constant at Laapproximate to2.5 fm. Hadron masses, light quark masses and meson decay constants are measured at five valence quark masses corresponding to m(PS)/m(V)approximate to0.8, 0.75, 0.7, 0.6 and 0.5. We also carry out complementary quenched simulations with the same improved actions. The quenched spectrum from this analysis agrees well in the continuum limit with the one of our earlier work using the standard action, quantitatively confirming the systematic deviation of the quenched spectrum from experiment, We find the two-flavor full QCD meson masses in the continuum limit to be much closer to experimental meson masses than those from quenched QCD. When using the K meson mass to fix the strange quark mass, the difference between quenched QCD and experiment of 2.6(-0.9)(+0.3)% for the K* meson mass and of 4.1(-1.6)(+0.5)% for the phi meson mass is reduced to 0.7(-1.7)(+1.1)% and 1.3(-2.5)(+1.8)% in full QCD, where the errors include estimates of systematic errors of the continuum extrapolation as well as statistical errors. Analyses of the J parameter yield a similar trend in that the quenched estimate in the continuum limit J =0.375(-0.009)(+0.039) increases to J=0.440(-0.031)(+0.061) in two-flavor full QCD, approaching the experimental value J approximate to0.48. We take these results as manifestations of sea quark effects in two-flavor full QCD. For baryon masses full QCD values for strange baryons such as Xi and Omega are in agreement with experiment, while they differ increasingly with decreasing strange quark content, resulting in a nucleon mass higher than experiment by 10% and a Delta mass by 13%. The pattern suggests finite size effects as -a passible origin for this deviation. For light quark masses in the continuum limit we obtain in m(ud)((MS) over bar)(2 GeV) = 3.44(-0.22)(+0.14) MeV and m(s)((MS) over bar) (2 GeV) =88(-6)(+4) MeV (K-input) and m(s)(MS) over bar (2 GeV) = 90(-11)(+5) MeV (phi-input), which are reduced by about 25% compared to the values in quenched QCD. We also present results for decay constants where large scaling violations obstruct a continuum extrapolation, The need for a nonperturbative estimate of renormalization factors is discussed.

DOI： 10.1103/PhysRevD.65.054505

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We report on a calculation of B-K with domain-wall fermion action in quenched QCD. Simulations are made with a renormalization group improved gauge action at beta = 2.6 and 2.9 corresponding to a(-1) approximate to 2 and 3 GeV. Effects, due to finite fifth dimensional size N-5 and finite spatial size N-sigma are examined in detail. Matching to the continuum operator is made perturbatively at one loop order. We obtain B-K(mu = 2 GeV) = 0.5740(61)(191), where the first error is statistical and the second error represents an estimate of scaling violation and O(alpha (2)) errors in the renormalization factor added in quadrature, as an estimate of the continuum value in the modified minimal subtraction ((MS) over bar) scheme with naive dimensional regularization. This value is consistent, albeit somewhat small, with B-K(mu = 2 GeV) = 0.068(42) obtained b the JLQCD Collaboration using the Kogut-Susskind quark action. Results for light quark masses are also reported.

DOI： 10.1103/PhysRevD.64.114506

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We present a study of the topological susceptibility in lattice QCD with two degenerate flavors of dynamical quarks. The topological charge is measured on gauge configurations generated with a renormalization group improved gauge action and a mean held improved clover quark action at three values of beta = 6/g(2) with four sea quark masses at each beta. The lattice spacings at these beta 's are a approximate to 0.22, 0.16 and 0.11 fm at the physical up and down quark mass, which are fixed by the physical rho meson mass. The study is supplemented by simulations of pure SU(3) gauge theory with the same gauge action at 5 values of beta with lattice spacings 0.09 fm less than or similar toa less than or similar to0.27 fm. We employ a field-theoretic definition of the topological charge together with cooling. For the topological susceptibility in the continuum limit of pure SU(3) gauge theory we obtain chi (1/4)(t) = 197(-16)(+13) MeV where the error shows statistical and systematic ones added in quadrature, In full QCD chi (t) at heavy sea quark masses is consistent with that of pure SU(3) gauge theory. A decrease of chi (t) toward light quark masses, as predicted by the anomalous Ward-Takahashi identity for U(1) chiral symmetry, becomes clearer for smaller lattice spacings. The cross over in the behavior of chi (t) from heavy to light sea quark masses is discussed.

DOI： 10.1103/PhysRevD.64.114501

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society  

We present a dynamical lattice calculation with two flavors for bottomonium states with an additional gluonic excitation. Using improved actions for the quarks and gauge fields at a lattice spacing of a≈0.1 fm, we find 10.977(61)(62) GeV for the energy of the lowest lying bb̅ g hybrid, where the first error is statistical and the second denotes the systematic uncertainty due to the determination of scale. In a parallel quenched simulation we demonstrate explicitly that vacuum polarization effects are less than 10% of the splitting with the ground state.

DOI： 10.1103/physrevd.64.097505

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We present the results of a first study of the equation of state in finite-temperature QCD with two flavors of Wilson-type quarks. The simulations are made on lattices with a temporal size Nt=4 and 6, using a renormalization-group-improved action for the gluon sector and a mean-field-improved clover action for the quark sector. The lines of constant physics corresponding to fixed values of the ratio mPS/mV of the pseudoscalar to vector meson masses at zero temperature are determined, and the beta functions which describe the renormalization-group flow along these lines are calculated. Using these results, the energy density and the pressure are calculated as functions of temperature along the lines of constant physics in the range mPS/mV =0.65-0.95. The quark mass dependence in the equation of state is found to be small for mPS/mV≲0.8. A comparison of the results for Nt=4 and Nt=6 lattices shows a significant scaling violation present in the Nt=4 results. At high temperatures the results for Nt=6 are quite close to the continuum Stefan-Boltzmann limit, suggesting the possibility of a precise continuum extrapolation of thermodynamic quantities from simulations at Nt≳6. © 2001 The American Physical Society.

DOI： 10.1103/PhysRevD.64.074510

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Finite temperature SU(3) gauge theory is studied on anisotropic lattices using the standard plaquette gauge action. The equation of state is calculated on 163×8, 203×10, and 243×12 lattices with the anisotropy ξ ≡as/at=2, where as and at are the spatial and temporal lattice spacings. Unlike the case of the isotropic lattice on which Nt=4 data deviate significantly from the leading scaling behavior, the pressure and energy density on an anisotropic lattice are found to satisfy well the leading 1/Nt2 scaling from our coarsest lattice Nt/ξ=4. With three data points at Nt/ξ=4, 5 and 6, we perform a well controlled continuum extrapolation of the equation of state. Our results in the continuum limit agree with a previous result from isotropic lattices using the same action, but have smaller and more reliable errors. © 2001 The American Physical Society.

DOI： 10.1103/PhysRevD.64.074507

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society (APS)  

DOI： 10.1103/physrevd.64.054504

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We present a calculation of the B and D meson decay constants in lattice QCD with two (Nf=2) flavors of light dynamical quarks, using an 0(a)-improved Wilson action for both light and heavy quarks and a renormalization-group improved gauge action. Simulations are made at three values of lattice spacing a = 0.22,0.16,0.11 fm and four values of sea quark mass in the range mPS/invO.S- 0.6. Our provisional estimate for the continuum values of the decay constants are fBd = 208(10)(29) MeV, fBs = 250(10)(35)(-0 +8) MeV,fDd=225(14)(40) MeV,fDj=267(13)(48)(°) MeV for Nf=2 where the statistical and systematic errors are separately listed, and the third error for/Bj and/Dj shows the uncertainty of the determination of the strange quark mass. We also carry out a set of quenched simulations using the same action to make a direct examination of sea quark effects. Taking the ratio of results for Nf=2 and Af=0, we obtain fbd Nf=2/2T°=1.11(6)£r 2//£f°= U4(5)4r11°= l.03(6)4f 2/£f °= 1.07(5). They show a 10-15% increase in the Nf=2 results over those of Nj=Q for the B meson decay constants, while evidence for such a trend is statistically less clear for the D meson decay constants. ©2001 The American Physical Society.

DOI： 10.1103/PhysRevD.64.034505

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The American Physical Society  

We investigate the chiral properties of quenched domain-wall QCD (DWQCD) at the lattice spacings a-1≃1 and 2 GeV for both plaquette and renormalization-group (RG) improved gauge actions. In the case of the plaquette action we find that the quark mass defined through the axial Ward-Takahashi identity remains non-vanishing in the DWQCD chiral limit that the bare quark mass mf→0 and the length of the fifth dimension Ns→∞, indicating that chiral symmetry is not realized with quenched DWQCD up to a-1≃2 GeV. The behavior is much improved for the RG-improved gauge action: while a nonvanishing quark mass remains in the chiral limit at a-1≃1 GeV, the result at a-1≃2 GeV is consistent with an exponentially vanishing quark mass in the DWQCD chiral limit, indicating the realization of exact chiral symmetry. An interpretation and implications are briefly discussed.

DOI： 10.1103/physrevd.63.114504

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Recent developments in finite-temperature QCD with dynamical quarks are reviewed focusing on the topics of critical temperature, the equation of state, and critical behaviors around the chiral phase transition.

DOI： 10.1016/S0920-5632(01)00922-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Chiral properties of QCD formulated with the domain-wall fermion (DWQCD) are studied using the anomalous quark mass ms, and the spectrum of the l-dimensional Wilson-Dirac operator. Numerical simulations are made with the standard plaquette gauge action and a renormalization-group improved gauge action. Results are reported on the density of zero eigenvalue obtained with the accumulation method, and a comparison is made with the results for m(5q).

DOI： 10.1016/S0920-5632(01)00897-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We explore the possibility for an evaluation of non-leptonic DeltaS = 1 K decay amplitudes through the calculation of K --&gt; pi matrix elements using domain-wall QCD. The relation between the physical K --&gt; pi pi matrix elements and K --&gt; pi matrix elements deduced from chiral perturbation theory is recapitulated. Quenched numerical simulations are performed on an 16(3) x 32 x 16 lattice at a lattice spacing a(-1) approximate to 2GeV for both the standard plaquette gauge action and a renormalization-group improved gauge action, and reasonable signals for K --&gt; pi matrix elements are obtained. Preliminary results are reported on the K --&gt; pi pi matrix elements, and results from two actions are compared.

DOI： 10.1016/S0920-5632(01)00933-1

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present the final results of the CP-PACS calculation of the light hadron spectrum and quark masses with two flavors of dynamical quarks. Simulations are made with a renormalization-group improved gauge action and a mean-field improved clover quark action for sea quark masses corresponding to m(PS)/m(V) approximate to 0.8-0.6 and the lattice spacing a 0.22-0.11 fm. For the meson spectrum in the continuum limit a clearly improved agreement with experiment is observed compared to the quenched case, demonstrating the importance of sea quark effects. For light quark masses we obtain m(ud)((MS) over bar)(2GeV) = 3.44(-0.22)(+0.14) MeV and m(s)((MS) over bar) (2GeV) = 88(-6)(+4) MeV (K-input) and m(s)((MS) over bar) (2GeV) = 90(-11)(+5) MeV (phi -input), which are reduced by about 25% compared to the values in quenched QCD.

DOI： 10.1016/S0920-5632(01)00961-6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present the results of quenched charmonium spectrum for S- and P-states, obtained by a relativistic heavy quark method on anisotropic lattices. Simulations are carried out using the standard plaquette gauge action and a meanfield-improved clover quark action at a(t)(-1) = 3-6 GeV with the renormalized anisotropy fixed to xi drop a(s)/a(t) = 3. We study the scaling of our fine and hyperfine mass splittings, and compare with previous results.

DOI： 10.1016/S0920-5632(01)00951-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We report on a calculation of B-K with domain wall fermion action in quenched QCD. Simulations are made with a renormalization group improved gauge action at beta = 2.6 and 2.9 corresponding to a(-1) approximate to 2GeV and 3GeV. Effects due to finite fifth dimensional size N-5 and finite spatial size N-sigma are examined in detail. Matching to the continuum operator is made perturbatively at one loop order. We obtain B-K (mu = 2GeV) = 0.5746(61), where the error is statistical only, as an estimate of the continuum value in the (MS) over bar scheme with naive dimensional regularization. This value is smaller but consistent with B-K (mu = 2GeV) = 0.628(42) obtained by the JLQCD Collaboration using the Kogut-Susskind quark action. Results for strange quark mass are also reported.

DOI： 10.1016/S0920-5632(01)00934-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Deriving the light hadron spectrum from first principles of QCD has been a fundamental issue in elementary particle physics since the mid-1970s, when QCD was established. With this goal in mind, we have carried out large-scale simulations of lattice QCD on the CP-PACS computer. In this article, we present results for the light hadron spectrum derived in the quenched approximation to lattice QCD. We find that although the global structure of the observed spectrum is reproduced, the quenched spectrum systematically deviates from experiment when examined with an accuracy at better than a 10% level. Results for light quark masses are also reported. Another simulation of full QCD done recently (also on the CP-PACS computer) shows indications that the discrepancy observed in quenched QCD is significantly reduced by the introduction of two flavors of light dynamical quarks.

DOI： 10.1143/PTP.105.37

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We study the finite-temperature phase structure and the transition temperature of QCD with two flavors of dynamical quarks on a lattice with the temporal size Nt=4, using a renormalization group improved gauge action and the Wilson quark action improved by the clover term. The region of a parity-broken phase is identified, and the finite-temperature transition line is located on a two-dimensional parameter space of the coupling (β=6/g2) and hopping parameter K. Near the chiral transition point, defined as the crossing point of the critical line of the vanishing pion mass and the line of finite-temperature transition, the system exhibits behavior well described by the scaling exponents of the three-dimensional O(4) spin model. This indicates a second-order chiral transition in the continuum limit. The transition temperature in the chiral limit is estimated to be Tc=171(4) MeV. © 2000 The American Physical Society.

DOI： 10.1103/PhysRevD.63.034502

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society  

We study the effects of two dynamical sea quarks on the spectrum of heavy quarkonia. Within the non-relativistic approach to lattice QCD we find sizable changes to the hyperfine splitting, but we do not observe any changes for the fine structure. We also investigate the scaling behavior of our results for several different lattice spacings.

DOI： 10.1103/physrevd.62.114508

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

Light quark masses are calculated in lattice QCD with two degenerate flavors of dynamical quarks. The calculations are made with improved actions with lattice spacing a = 0.22-0.11 fm. In the continuum limit we find m(ud)((M) over barS) (2 GeV) =3.44(-0.22)(+0.14)MEV using the pi and rho meson masses as physical input, uum limit we find m,d and m(s) ((M) over barS)(2 GeV) = 88(-6)(+4) MeV or 90(-11)(+5) MeV with the K or phi meson mass as additional input. The quoted errors represent statistical and systematic combined, the latter including those from continuum and chiral extrapolations, and from renormalization factors. Compared to quenched results, two flavors of dynamical quarks reduce quark masses by about 25%.

DOI： 10.1103/PhysRevLett.85.4674

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Physical Society  

Pure lattice SU(2) Yang-Mills theory in five dimensions is considered, where an extra dimension is compactified on a circle. Monte Carlo simulations indicate that the theory possesses a continuum limit with a nonvanishing string tension if the compactification radius is smaller than a certain value R M which is O(1/10) of the inverse of the square root of the string tension. We verify nonperturbatively the power-law running of the gauge coupling constant. Our method can be applied to the investigation of continuum limits in other higher-dimensional gauge theories.

DOI： 10.1103/physrevd.62.105025

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present results for the mass of the flavor singlet meson calculated on two-flavor full QCD configurations generated by the CP-PACS full QCD project. We also investigate topological charge fluctuations and their dependence on the sea quark mass.

DOI： 10.1016/S0920-5632(00)91611-6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present updated results of the CP-PACS calculation of the light hadron spectrum in N-f = 2 full QCD. Simulations are made with an RG-improved gauge action and a tadpole-improved clover quark action for sea quark masses corresponding to m(PS)/m(V) approximate to 0.8-0.6 and the lattice spacing a = 0.22-0.09 fm. A comparison of the N-f = 2 QCD spectrum with new quenched results, obtained with the same improved action, shows clearly the existence of sea quark effects in vector meson masses. Results for Light quark masses are also presented.

DOI： 10.1016/S0920-5632(00)91615-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present results for the equation of state for pure SU(3) gauge theory obtained with a renormalization-group (RG) improved action. The energy density and pressure are calculated on a 16(3) x 4 and a 32(3) x 8 lattice employing the integral method. Extrapolating the results to the continuum limit, we find the energy density and pressure to be in good agreement with those obtained with the standard plaquette action within the error of 3-4%.

DOI： 10.1016/S0920-5632(00)91681-5

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We study finite-temperature phase transition and equation of state for two-flavor QCD at N-t = 4 using an RG-improved gauge action and a meanfield-improved clover quark action. The pressure is computed using the integral method. The O(4) scaling of chiral order parameter is also examined.

DOI： 10.1016/S0920-5632(00)91673-6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We investigate the existence of chiral zero modes at a(-1) similar or equal to 1 GeV in quenched domain-wall QCD. Simulations are carried out for the plaquette and an RG-improved gauge actions on a 12(3) x 24 x N-s lattice with N-s = 10 - 50. We find that the pion mass in the chiral limit remains non-vanishing as N-s --&gt; infinity for both gauge actions. Possible origins of this non-vanishing pion mass are discussed.

DOI： 10.1016/S0920-5632(00)91747-X

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present results on an analysis of the decay constants f(Bd) and f(Bs) with two flavours of sea quark. The calculation has been carried out on 3 different bare gauge couplings and 4 sea quark masses at each gauge coupling, with m(pi)/m(rho), ranging from 0.8 to 0.6. We employ the Fermilab formalism to perform calculations with heavy quarks whose mass is in the range of the b-quark. A detailed comparison with a quenched calculation using the same action is made to elucidate the effects due to the sea quarks.

DOI： 10.1016/S0920-5632(00)91664-5

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We report on a study of B mesons on N-f = 2 full QCD configurations using an RG-improved gauge action, NRQCD heavy quark action and tadpole-improved clover light quark action. Results on the heavy-light spectrum and the decay constants from 16(3) x 32 lattices at a(-1) approximate to 1.5 GeV are presented, and compared with quenched results obtained with the same action combination at matching lattice spacings.

DOI： 10.1016/S0920-5632(00)91642-6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We report on recent results for the spectrum of heavy quarkonia. Using coarse and anisotropic lattices we achieved an unprecedented control over statistical and systematic errors for higher excited states such as exotic hybrid states. In a parallel study on isotropic lattices we also investigate the effect of two dynamical flavours on the spin structure of charmonium and bottomonium for several symmetric lattices.

DOI： 10.1016/S0920-5632(00)91660-8

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER PHYSICAL SOC  

We present results of a large-scale simulation for the flavor nonsinglet light hadron spectrum in quenched lattice QCD with the Wilson quark action. Hadron masses are calculated ai four values of lattice spacing in the range a approximate to 0.1-0.05 fm on lattices with a physical extent of 3 fm five quark masses corresponding to m(pi)/m(rho) = 0.75-0.4. The calculated spectrum in the continuum limit shows a systematic deviation from experiment, though the magnitude of deviation is contained within 11%. Results for decay constants and light quark masses are also reported.

DOI： 10.1103/PhysRevLett.84.238

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

A lattice study of the equation of state for pure SU(3) gauge theory using a renormalization-group (RG) improved action is presented. The energy density and pressure are calculated on a (Formula presented) and a (Formula presented) lattice employing the integral method. Extrapolating the results to the continuum limit, we find the energy density and pressure to be in good agreement with those obtained with the standard plaquette action within the error of 3–4 %. © 1999 The American Physical Society.

DOI： 10.1103/PhysRevD.60.094510

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMERICAN PHYSICAL SOC  

We report on a study of heavy quark bound states containing an additional excitation of the gluonic degrees of freedom. To this end we employ the nonrelativistic QCD approach on coarse and asymmetric lattices, where we discard vacuum polarization effects and neglect all spin-correction terms. We find a clear hybrid signal on all our lattices (a(s) = 0.15,..., 0.47 fm). We have studied in detail the lattice spacing artifacts, finite volume effects,and mass dependence. Within the above approximations we predict the lowest lying hybrid excitation in charmonium to be 1.323(13) GeV above the ground state, where we use the 1P-1S splitting to set the scale. The bottomonium hybrid was found to be 1.542(8) GeV above its ground state. [S0031-9007(99)09172-3].

DOI： 10.1103/PhysRevLett.82.4396

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present a preliminary analysis of the heavy-heavy spectrum and heavy-light decay constants in full QCD, using a tadpole-improved SW quark action and an RG-improved gauge action on a 16(3) x 32 lattice with four sea quark masses corresponding to m(pi)/m(p) approximate to 0.8, 0.75, 0.7, 0.6 and a(-1) approximate to 1.3 GeV. We focus particularly on the effect of sea quarks on these observables.

DOI： 10.1016/S0920-5632(99)85078-6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We report results on the static quark potential in two-flavor full QCD. The calculation is performed for three values of lattice spacing a(-1) approximate to 0.9, 1.3 and 2.5 GeV on 12(3) x 24, 16(3) x 32 and 24(3) x 48 lattices respectively, at sea quark masses corresponding to m(pi)/m(p) approximate to 0.8-0.6. An RG-improved gauge action and a tadpole-improved SW clover quark action are employed. We discuss scaling of m(p)/root sigma and effects of dynamical quarks on the potential.

DOI： 10.1016/S0920-5632(99)85027-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We propose a new non-perturbative method to compute derivatives of gauge coupling constants with respect to anisotropic lattice spacings (anisotropy coefficients). Our method is based on a precise measurement of the finite temperature deconfining transition curve in the lattice coupling parameter space extended to anisotropic lattices by applying the spectral density method. We determine the anisotropy coefficients for the cases of SU(2) and SU(3) gauge theories. A longstanding problem, when one uses the perturbative anisotropy coefficients, is a nonvanishing pressure gap at the deconfining transition point in the SU(3) gauge theory. Using our non-perturbative anisotropy coefficients, we find that this problem is completely resolved.

DOI： 10.1016/S0920-5632(99)85089-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We report the final results of the CP-PACS calculation for the quenched light hadron spectrum with the Wilson quark action. Our data support the presence of quenched chiral singularities, and this motivates us to use mass formulae based on quenched chiral perturbation theory in order to extrapolate hadron masses to the physical point. Hadron masses and decay constants in the continuum limit show unambiguous systematic deviations from experiment. We also report the results for light quark masses.

DOI： 10.1016/S0920-5632(99)85018-X

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We report on an on-going two-flavor full QCD study on CP-PACS using an RG-improved gauge action and a tadpole-improved SW quark action. Runs are made for three lattice spacings a(-1) approximate to 0.9, 1.3, and 2.5 GeV on 12(3) x 24, 16(3) x 32, and 24(3) x 48 lattices. Four sea quark masses having m(PS)/m(V) approximate to 0.8-0.6 are simulated, for each of which hadron masses are evaluated for valence quark masses corresponding to m(PS)/m(V) approximate to 0.8-0.5. Results for hadron and light quark masses are presented and compared with those obtained in quenched QCD.

DOI： 10.1016/S0920-5632(99)85019-1

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We propose a new nonperturbative method to compute the derivatives of gauge coupling constants with respect to anisotropic lattice spacings (anisotropy coefficients), which are required in an evaluation of thermodynamic quantities from numerical simulations on the lattice. Our method is based on a precise measurement of the finite temperature deconfining transition curve in the lattice coupling parameter space extended to anisotropic lattices by applying the spectral density method. We test the method for the cases of SU(2) and SU(3) gauge theories at the deconfining transition point on lattices with the lattice size in the time direction (Formula presented) In both cases, there is a clear discrepancy between our results and perturbative values. A long standing problem, when one uses the perturbative anisotropy coefficients, is a nonvanishing pressure gap at the deconfining transition point in the SU(3) gauge theory. Using our nonperturbative anisotropy coefficients, we find that this problem is completely resolved: we obtain (Formula presented) and (Formula presented) on (Formula presented) and 6 lattices, respectively. © 1998 The American Physical Society.

DOI： 10.1103/PhysRevD.58.094505

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We study the relation between the abelian monopole condensation and the deconfinement phase transition of the finite-temperature pure QCD, and find that the expectation value of the Polyakov loop becomes zero when a long monopole loop is distributed uniformly in the configuration of the confinement phase as suggested in the previous Monte-Carlo simulations, whereas this value becomes non-zero when the long monopole loop disappears in the deconfinement phase. We also discuss the relation between the monopole picture and the spontaneous breaking of Z(N) symmetry that is the usual interpretation of the deconfinement transition in the finite-temperature SU(N) gauge theory.

DOI： 10.1016/S0375-9474(97)00670-2

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The critical properties of the abelian Polyakov loop and the Polyakov loop in terms of Dirac string are studied in finite temperature abelian projected SU(2) QCD. We evaluate the critical point and the critical exponents from each Polyakov loop in the maximally abelian gauge using the finite-size scaling analysis. Abelian dominance in this case is proved quantitatively. The critical point of each abelian Polyakov loop is equal to that of the non-abelian Polyakov loop within the statistical errors. Also, the critical exponents are in good agreement with those from non-abelian Polyakov loops. (C) 1997 Published by Elsevier Science B.V.

DOI： 10.1016/S0370-2693(97)00319-5

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Effective monopole actions for various extended monopoles are derived from vacuum configurations after abelian projection in the maximally abelian gauge in T = 0 and T not equal 0 SU(3) lattice QCD. The actions obtained appear to be independent of the lattice volume adopted. At zero temperature, monopole condensation is seen to occur from energy-entropy balance in the strong coupling region. Larger beta is included in the monopole condensed phase as more extended monopoles are considered. The scaling seen in the SU(2) case is not yet observed. The renormalization flow diagram suggests the existence of an infrared fixed point. A hysteresis behavior is seen around the critical temperature in the case of the T not equal 0 action. (C) 1997 Elsevier Science B.V.

DOI： 10.1016/S0370-2693(97)00066-X

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We study the relation between the abelian monopole condensation and the deconfinement phase transition of the finite-temperature pure QCD. The expectation value of the monopole contribution to the Polyakov loop becomes zero when a long monopole loop is distributed uniformly in the configuration of the confinement phase. On the other hand, it becomes non-zero when the long monopole loop disappears in the deconfinement phase. We also discuss the relation between the monopole behaviors and the usual interpretation of the spontaneous breaking of Z(N) symmetry in finite-temperature SU(N) QCD. It is found that the boundary condition of the space direction is important to understand tile Z(N) symmetry in terms of the monopoles.

DOI： 10.1016/S0920-5632(96)00696-2

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Three topics about monopole dynamics after abelian projection are reported. The first is the new and detailed analyses of SU(2) monopole action obtained after the block-spin transformation on the dual lattice. The b = na(beta) dependence for all couplings are well fitted with a universal curve. The distance dependence of the couplings is well reproduced by a massive propagator with the mass m = 0.8 in unit of b. The second is the SU(3) monopole action recently obtained. The third is new interesting gauges showing abelian and monopole dominances as in the maximally abelian gauge.

DOI： 10.1016/S0920-5632(96)00709-8

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The disorder parameter of confinement-deconfinement phase transition based on the monopole action determined previously in SU(2) QCD are investigated. We construct an operator which corresponds to the order parameter defined in the abelian Higgs model. The operator shows proper behaviors as the disorder parameter in the numerical simulations of finite temperature QCD.

DOI： 10.1016/S0920-5632(96)00703-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The critical properties of the abelian Polyakov loop and the Polyakov loop in terms of Dirac string are studied in finite temperature abelian projected SU(2) QCD. The critical point and the critical exponents are determined from each Polyakov loop in the maximally abelian gauge using the finite-size scaling analyses. Those critical points and exponents are in good agreement with those from non-abelian Polyakov loops.

DOI： 10.1016/S0920-5632(96)00701-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We studied a behavior of monopole currents in the high temperature (deconfinement) phase of abelian projected finite temperature SU(2) QCD in maximally abelian gauge. Wrapped monopole currents closed by periodic boundary play an important role for the spatial string tension that is a non-perturbative quantity in the deconfinement phase. The wrapped monopole current density seems to be non-vanishing in the continuum limit. These results may be related to Polyakov's analysis of the confinement mechanism using monopole gas in 3-dimensional SU(2) gauge theory with Higgs fields.

DOI： 10.1016/0370-2693(96)00245-6

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We investigated the gauge (in)dependence of the confinement mechanism due to monopole condensation in SU(2) lattice QCD by various abelian projections. We found (1) the string tension can be reproduced by monopoles alone also in Polyakov gauge and (2) the behaviors of the Polyakov loop at the critical temperature seem to be explained by the uniformity breaking of the monopole currents in every gauge.

DOI： 10.1016/0920-5632(96)00066-7

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

To find a perfect lattice action in terms of monopole action on the dual lattice, we performed simulations of a monopole effective action obtained numerically from vacuum configurations in SU(2) QCD. Although the Polyakov loop behavior near T-c is well reproduced by the action, a small but repulsive term is needed in addition to get the string tension correctly. It is reported also a monopole effective action in SU(3) QCD which is expressed by one kind of monopole currents.

DOI： 10.1016/0920-5632(96)00054-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We investigated a behavior of monopole currents in the high temperature phase of abelian projected finite temperature SU(2) QCD in maximally abelian gauge. Wrapped monopole currents which are closed by periodic boundary play an important role for the spatial string tension. And the wrapped monopole current density seems to be non-vanishing in the continuum limit. These results may be related to Polyakov's analysis of the confinement mechanism using monopole gas in 3-dimensional SU(2) gauge theory with Higgs fields.

DOI： 10.1016/0920-5632(96)00117-X

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Monopole and photon contributions to abelian Wilson loops are calculated using Monte-Carlo simulations of finite-temperature SU(2) QCD in the maximally abelian gauge. The string tension is reproduced by monopole contribution alone also in finite temperature SU(2) QCD. The spatial string tension scales as root sigma proportional to g(2)(T)T and is reproduced almost by monopole contribution alone. Each configuration has one long monopole loop, and the long monopole loops alone are responsible for the string tension in the confinement phase. On the other hand, the spatial string tension in the deconfinement phase is reproduced by wrapped monopole loops alone.

DOI： 10.1016/0920-5632(95)00286-I

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Monopole and photon contributions to abelian Wilson loops are calculated using Monte-Carlo simulations of finite-temperature SU(2) QCD in the maximally abelian gauge. Long monopole loops alone are responsible for the behavior of the string tension in the confinement phase. Short monopole loops and photons do not contribute to the string tension. The abelian and the monopole spatial string tensions (both of which agree with the full ones for beta &lt; beta(c)) show a g(4)(T)T-2 scaling behavior in the deconfinement phase. The abelian spatial string tension is in agreement with the full one even in the deconfinement phase.

DOI： 10.1016/0370-2693(94)01457-N

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

After making an abelian projection in the maximally abelian gauge, we measure the distribution of abelian electric flux and monopole currents around an abelian Wilson loop iii SU (2) and SU (3) QCD. The (dual) Meissner effect is observed clearly. The vacua in the confinement phases of SU(2) and SU(3) are both at around the border between type-1 and type-2 (dual) superconductor.

DOI： 10.1016/0920-5632(94)90337-9

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

DOI： 10.11316/jpsgaiyo.71.1.0_55

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

DOI： 10.11316/jpsgaiyo.71.1.0_53

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

DOI： 10.11316/jpsgaiyo.70.1.0_50

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：素粒子論グループ 素粒子論研究編集部  

DOI： 10.24532/soken.119.4C_F111

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：素粒子論グループ 素粒子論研究編集部  

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記述言語：日本語   出版者・発行元：素粒子論グループ 素粒子論研究 編集部  

DOI： 10.24532/soken.118.4_D125

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：原子核研究編集委員会  

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記述言語：日本語   出版者・発行元：社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：英語   出版者・発行元：素粒子論グループ 素粒子論研究 編集部  

We will review the recent studies of the QCD phase structure by numerical simulations in the low density region. It is important to investigate the phase structure and the equation of state of QCD in the low density regime which is interesting for heavy-ion collision experiments. The studies of the phase structure and the equation of state can provide basic input for the analysis of the experimental signatures for QGP formation. In the last several years, remarkable progress in exploring the QCD phase structure in the temperature (T) and quark chemical potential (μ_q) plane have been made in numerical studies of lattice QCD. The phase transition line, separating hadron phase and quark-gluon plasma phase, was investigated from μq=0 to finite μ_q [1, 2, 3, 4, 5], and the equation of state was also analyzed quantitatively at low density [3, 6]. Moreover the study of the endpoint of first order phase transition line in the (T, μ_q) plane, whose existence is suggested by phenomenological studies [7, 8], is particularly interesting both from the experimental and theoretical points of view. To find this endpoint, event by event fluctuations have been measured in heavy ion collisions. In this report, we review recent progress of lattice QCD simulations, highlighting the study of the critical endpoint in the (T,μ_q) plane. The lattice QCD at nonzero baryon density is known to have a serious problem called "sign problem", however this problem is not very serious for the studies in the low density region, and interesting results have been gradually obtained using the following approaches.

DOI： 10.24532/soken.114.2_B45

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：素粒子論グループ  

DOI： 10.24532/soken.112.3_C85

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：社団法人日本物理学会  

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）   出版者・発行元：素粒子論グループ  

この報告では、有限温度・有限密度格子QCDの数値シミュレーションによる研究の最近の発展についてレビューする。特に、フレーバー数2と3のQCDの相転移温度の研究、カイラル相転移の臨界現象の性質、クォーク・グルーオン・プラズマの状態方程式といった話題について議論する。

DOI： 10.24532/soken.103.1_A41

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：素粒子論グループ 素粒子研究編集部  

我々、金沢のグループでは、QCDにおけるクォークの閉じ込め機構が、monopoleの凝縮による、Dnal Meissner効果として理解できるかどうかを、Lattice QCDのMonte-Carlo simulationによって確かめるといった研究をつづけています。ここでは、SU(2)pnre QCDの有限温度閉じ込め・非閉じ込め相転移における、monopoleの役割について、我々が得た結果を報告します。

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記述言語：日本語   出版者・発行元：素粒子論グループ 素粒子研究編集部  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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開催年月日： 2022年3月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン（岡山大学）   国名：日本国  

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開催年月日： 2021年10月

記述言語：英語   会議種別：口頭発表（招待・特別）  

国名：日本国  

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開催年月日： 2021年7月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：マサチューセッツ、MIT (オンライン)   国名：アメリカ合衆国  

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開催年月日： 2021年3月

会議種別：口頭発表（一般）  

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開催年月日： 2020年9月

記述言語：日本語   会議種別：口頭発表（一般）  

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開催年月日： 2020年8月

記述言語：日本語   会議種別：ポスター発表  

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開催年月日： 2020年5月

記述言語：日本語   会議種別：口頭発表（招待・特別）  

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開催年月日： 2020年1月

記述言語：英語   会議種別：ポスター発表  

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記述言語：日本語   会議種別：口頭発表（一般）  

開催地：山形大学、山形市  

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記述言語：日本語   会議種別：口頭発表（一般）  

開催地：京都大学基礎物理学研究所  

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記述言語：英語   会議種別：ポスター発表  

開催地：筑波大学東京キャンパス  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：武漢, 中国  

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記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：東京工業大学  

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記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：愛媛大学、松山市  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：Kyoto University, Kyoto, Japan  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Ibaraki Quantum Beam Research Center, Tokai, Ibaraki, Japan  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：高エネルギー加速器研究機構、東海キャンパス、茨城県東海村  

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記述言語：英語   会議種別：ポスター発表  

開催地：Granada, Spain  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：University of Southampton, Southampton, UK  

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記述言語：英語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

開催地：新潟大学  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：神戸市  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：華中師範大学, 武漢, 中国  

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記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：筑波大学計算科学研究センター, つくば市  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Tsukuba, Japan  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：京都  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：Bielefeld University, Bielefeld, Germany  

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記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

開催地：つくば市  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：St. Petersburg, Russia  

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記述言語：日本語   会議種別：口頭発表（一般）  

開催地：埼玉県和光市  

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記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：京都大学基礎物理学研究所  

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記述言語：英語   会議種別：ポスター発表  

開催地：Columbia University, New York, USA  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Darmstadt, Germany  

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記述言語：英語   会議種別：口頭発表（基調）  

開催地：筑波  

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記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：宮城県鳴子温泉  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：京都  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Regensburg, Germany  

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記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：高知大学  

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記述言語：日本語   会議種別：ポスター発表  

開催地：京都大学基礎物理学研究所  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：Mainz, Germany  

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記述言語：日本語   会議種別：口頭発表（一般）  

開催地：富山県、国立立山青少年自然の家  

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記述言語：日本語   会議種別：口頭発表（一般）  

開催地：広島大学  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：奈良県新公会堂  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Kobe, Japan  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Wuhan, China  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：Regensburg, Germany  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：The Galileo Galilei Institute for Theoretical Physics, Florence, Italy  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：Cairns, Australia  

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記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：東京大学、物性研究所  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：Kyoto, Japan  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：高エネルギー加速器研究機構  

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記述言語：日本語   会議種別：口頭発表（一般）  

開催地：三重県志摩市  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Keio University, Kanagawa, Japan  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Wuhan, China  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Upton, New York, USA  

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記述言語：日本語   会議種別：口頭発表（一般）  

開催地：弘前大学  

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記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：東京大学理学部  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：San Carlos, Mexico  

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記述言語：英語   会議種別：ポスター発表  

開催地：Annecy, France  

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記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Tsukuba, Ibaraki, Japan  

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記述言語：英語   会議種別：口頭発表（一般）  

開催地：Mishima, Shizuoka, Japan  

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記述言語：日本語   会議種別：口頭発表（基調）  

開催地：埼玉県和光市、理化学研究所  

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