Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

It has been known for a long time that hyperons produced in hadronic collisions are polarized perpendicular to the production plane of the reaction. This effect cannot be described by using twist-2 collinear parton correlators only. Here we compute the contribution of twist-3 fragmentation functions to the production of transversely polarized hyperons in unpolarized proton-proton collisions in the framework of collinear factorization. By taking into account the relations among the relevant twist-3 fragmentation functions which follow from the QCD equation of motion and the Lorentz invariance property of the correlators, we present the leading-order cross section for this term.

DOI： 10.1103/PhysRevD.95.114013

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arXiv

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We compute the contribution from the longitudinally polarized proton to the twist-3 double-spin asymmetry A(LT) in inclusive (light) hadron production from proton-proton collisions, i.e., p up arrow(p) over right arrow -> h X. We show that using the relevant QCD equation-of-motion relation and Lorentz invariance relation allows one to eliminate the twist-3 quark-gluon correlator (associated with the longitudinally polarized proton) in favor of one-variable twist-3 quark distributions and the (twist-2) transversity parton density. Including this result with the twist-3 pieces associated with the transversely polarized proton and unpolarized final-state hadron (which have already been calculated in the literature), we now have the complete leading-order cross section for this process. (C) 2016 The Authors. Published by Elsevier B.V.

DOI： 10.1016/j.physletb.2016.05.043

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We investigate the behavior under Lorentz transformations of perturbative coefficient functions in a collinear twist-3 formalism relevant for high-energy observables including transverse polarization of hadrons. We argue that those perturbative coefficient functions can, a priori, acquire quite different yet Lorentz-invariant forms in various frames. This somewhat surprising difference can be traced back to a general dependence of the perturbative coefficient functions on light cone vectors which are introduced by the twist-3 factorization formulas and which are frame-dependent. One can remove this spurious frame dependence by invoking so-called Lorentz invariance relations (LIRs) between twist-3 parton correlation functions. Some of those relations for twist-3 distribution functions were discussed in the literature before. In this paper we derive the corresponding LIRs for twist-3 fragmentation functions. We explicitly demonstrate that these LIRs remove the light cone vector dependence by considering transverse spin observables in the single-inclusive production of hadrons in lepton-nucleon collisions, lN -> hX. With the LIRs in hand, we also show that twist-3 observables in general can be written solely in terms of three-parton correlation functions.

DOI： 10.1103/PhysRevD.93.054024

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arXiv

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We compute the contribution from the twist-3 fragmentation function for light hadron production in collisions between transversely and longitudinally polarized protons, i.e., p up arrow(p) over right arrow -> h X, which can cause a double-spin asymmetry (DSA) A(LT). This is a naive T-even twist-3 observable that we analyze in collinear factorization using both Feynman gauge and lightcone gauge as well as give a general proof of color gauge invariance. So far only twist-3 effects in the transversely polarized proton have been studied for A(LT) in p up arrow(p) over right arrow -> h X. However, there are indications that the naive T-odd transverse single-spin asymmetry (SSA) A(N) in p up arrow p -> h X is dominated not by such distribution effects but rather by a fragmentation mechanism. Therefore, one may expect similarly that the fragmentation contribution is important for A(LT). Given possible plans at RHIC to measure this observable, it is timely to provide a calculation of this term. (C) 2015 The Authors. Published by Elsevier B.V.

DOI： 10.1016/j.physletb.2015.11.014

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We investigate the transverse polarization of a hyperon produced in the high-energy unpolarized proton-proton collision, pp -> Lambda up arrow X, based on the collinear twist-3 factorization formalism. We focus on the contribution from the twist-3 distribution in one of the unpolarized proton and the transversity fragmentation function for the final hyperon. Utilizing the "master formula" for the soft-gluon-pole cross section, we clarify the reason for why it receives only the derivative term of the twist-3 distribution. We also present the first computation of the soft-fermion-pole cross section and found that it vanishes. This means that the derivative of the soft-gluon-pole function is the only source for the twist-3 cross section from the unpolarized twist-3 distribution, which provides a useful basis for a phenomenological analysis.

DOI： 10.1103/PhysRevD.92.094011

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arXiv

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We analyze the transverse single-spin asymmetry in direct photon production from proton-proton collisions, denoted A(N)(gamma,) within collinear twist-3 factorization. We provide a calculation of the contribution due to quark-gluon-quark correlations in the unpolarized proton as well as summarize previous studies on those effects in the polarized proton. Both soft-gluon poles and soft-fermion poles are considered. From this complete result we then estimate A(N)(gamma), including error bands due to uncertainties in the nonperturbative inputs, at kinematics relevant for planned measurements of this observable at the Relativistic Heavy Ion Collider. We find A(N)(gamma) can allow for a "clean" extraction of the Qiu-Sterman function, which could lead to a definitive solution to the so-called "sign-mismatch" crisis. Since we use the Sivers function extracted from semi-inclusive deep-inelastic scattering to develop our input for the Qiu-Sterman function, this reaction can also make a statement about the process dependence of the Sivers function.

DOI： 10.1103/PhysRevD.91.014013

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We present results for transverse single-spin asymmetries in proton-proton collisions at kinematics relevant for AFTER, a proposed fixed-target experiment at the Large Hadron Collider. These include predictions for pion, jet, and direct photon production from analytical formulas already available in the literature. We also discuss specific measurements that will benefit from the higher luminosity of AFTER, which could help resolve an almost 40-year puzzle of what causes transverse single-spin asymmetries in proton-proton collisions.

DOI： 10.1155/2015/257934

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arXiv

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We study the transverse single-spin asymmetry for single-hadron production in proton-proton collisions within the framework of collinear twist-3 factorization in quantum chromodynamics. By taking into account the contribution due to parton fragmentation, we obtain a very good description of all high transverse-momentum data for neutral and charged pion production from the Relativistic Heavy Ion Collider. Our study may provide the crucial step toward a final solution to the long-standing problem of what causes transverse single-spin asymmetries in hadronic collisions within quantum chromodynamics. We show for the first time that it is possible to simultaneously describe spin/azimuthal asymmetries in proton-proton collisions, semi-inclusive deep-inelastic scattering, and electron-positron annihilation by using collinear twist-3 factorization in the first process along with transverse-momentum-dependent functions extracted from the latter two reactions.

DOI： 10.1103/PhysRevD.89.111501

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We study the twist-3 three-gluon contribution to the single spin asymmetry in the light-hadron production in pp collision in the framework of the collinear factorization. We derive the corresponding cross-section formula in the leading order with respect to the QCD coupling constant. We also present a numerical calculation of the Relativistic Heavy Ion collider (RHIC) energy, using a model for the three-gluon correlation functions suggested by the asymmetry observed in the D-meson production at the RHIC.

DOI： 10.1103/PhysRevD.89.034029

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We study the contribution of the twist-3 fragmentation function to the single-transverse spin asymmetry in semi-inclusive deep inelastic scattering within the framework of the collinear factorization. Making use of the Ward-Takahashi identity in QCD, we establish the formalism in the Feynman gauge to calculate the nonpole contribution of the twist-3 fragmentation function to the asymmetry and derive the complete cross-section formula in the leading-order QCD perturbation theory. The obtained twist-3 hadronic tensor is shown to satisfy the electromagnetic gauge invariance. The behavior in the small transverse-momentum region for the five structure functions is also given. © 2013 American Physical Society.

DOI： 10.1103/PhysRevD.88.074022

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study the single transverse-spin asymmetry for the inclusive direct-photon and single-jet productions in the proton-proton collision based on the twist-3 mechanism in the collinear factorization. Taking into account all the effects from the twist-3 quark-gluon correlation functions inside a transversely polarized proton, we present a prediction for the asymmetries at the typical RHIC kinematics. In both processes we find sizable asymmetries in the forward region of the polarized proton while they are almost zero in the backward region. This implies that if one finds a nonzero asymmetries in the backward region in these processes, it should be ascribed wholely to the three-gluon correlations. We also find the soft-gluon pole contribution is dominant and the soft-fermion pole contribution is negligible in the whole Feynman-x region for these asymmetries. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physletb.2013.01.071

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We discuss the single transverse-spin asymmetry (SSA) to be observed in the D-meson production with large transverse-momentum in semi-inclusive deep inelastic scattering, ep(up arrow) -> eDX. This contribution is embodied as a twist-3 mechanism in the collinear factorization, which is induced by purely gluonic correlation inside the transversely-polarized nucleon, in particular, by the three-gluon correlation effects. The complete formula for the corresponding SSA in the leading-order QCD is expressed in terms of the four independent gluonic correlation functions and reveals the five independent structures with respect to the dependence on the azimuthal angle for the produced D-meson. We present the numerical calculations of the SSA formula at the kinematics relevant to a future electron-ion collider.

DOI： 10.1103/PhysRevD.85.114026

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We derive the single-spin-dependent cross section for the Drell-Yan lepton-pair production and the direct-photon production in the pp collision induced by the twist-3 three-gluon correlation functions in the transversely polarized nucleon in the leading order with respect to the QCD coupling constant. Combined with the contribution from the twist-3 quark-gluon correlation functions in the literature, this completes the twist-3 cross section for these processes. We also present a model calculation of the asymmetry for the direct-photon production at the relativistic heavy ion collider (RHIC) energy, demonstrating the sensitivity of the asymmetry to the form of the three-gluon correlation functions. In particular, we show that the asymmetry in the backward direction of the polarized nucleon is determined by the small-x behavior of the correlation functions.

DOI： 10.1103/PhysRevD.85.034030

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We study the single transverse-spin asymmetry for the inclusive open-charm production in the pp-collision, p(up arrow)p -> DX, induced by the three-gluon correlation functions in the polarized nucleon. We derive the corresponding twist-3 cross section formula in the leading order with respect to the QCD coupling constant. As in the case of the semi-inclusive deep inelastic scattering, ep(up arrow)p -> eDX, our result differs from the previous result in the literature. We also derive a "master formula'' which expresses the twist-3 cross section in terms of the gg -> c (c) over bar hard scattering cross section. We present a model calculation of the asymmetry at the RHIC energy, demonstrating the sensitivity of the asymmetry on the form of the three-gluon correlation functions.

DOI： 10.1103/PhysRevD.84.014026

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We study the single transverse-spin asymmetry for the Drell-Yan lepton pair production based on the twist-3 mechanism in the collinear factorization. We calculate all the hard-pole (HP) and the soft-fermion-pole (SFP) contributions to the single-spin-dependent cross section originating from the quark-gluon correlation functions in the transversely polarized nucleon in the leading order with respect to the QCD coupling constant. Combined with the soft-gluon-pole (SGP) contribution, this completes the corresponding twist-3 cross section. In the real photon limit, where all the HP contributions are transformed into the SFP contribution, we find that the SFP partonic hard cross section for the two independent quark-gluon correlation functions coincides in each scattering channel, as in the case of the inclusive light-hadron production. Our result enables one to extract the quark-gluon correlation functions from the forthcoming experiments at several facilities such as RHIC and J-PARC. (C) 2011 Elsevier B.V All rights reserved.

DOI： 10.1016/j.physletb.2011.06.021

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

We study the single transverse-spin asymmetry for the inclusive open-charm production in the pp-collision, p(up arrow)p -> DX, induced by the three-gluon correlation functions in the polarized nucleon. We derive the corresponding twist-3 cross section formula in the leading order with respect to the QCD coupling constant. As in the case of the semi-inclusive deep inelastic scattering, ep(up arrow)p -> eDX, our result differs from the previous result in the literature. We also derive a "master formula'' which expresses the twist-3 cross section in terms of the gg -> c (c) over bar hard scattering cross section. We present a model calculation of the asymmetry at the RHIC energy, demonstrating the sensitivity of the asymmetry on the form of the three-gluon correlation functions.

DOI： 10.1103/PhysRevD.84.014026

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

We study the single transverse-spin asymmetry for inclusive light-hadron productions in the proton-proton collision, p up arrow p -> hX (h = pi, K, eta), for the RHIC kinematics based on the twist-3 mechanism in the collinear factorization. The analysis includes all the contributions from the soft-gluon pole and the soft-fermion pole for the twist-3 quark-gluon correlation functions in the transversely polarized proton. After discussing the flavor decomposition and the P(T)-dependence of the asymmetry obtained in the previous analysis at the center-of-mass energy root S = 62.4 and 200 GeV, we will give a prediction for the asymmetry at root S = 500 GeV and also for the eta-meson production. We found slightly smaller asymmetry at root S = 500 GeV for pi(+/-,0) and K(+) compared with those at the lower energies. The asymmetry for the eta-meson turned out to be significantly larger than that for pi(0).

DOI： 10.1103/PhysRevD.83.114024

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

We derive a "master formula" for the contribution of the three-gluon correlation function in the nucleon to the twist-3 single-spin-dependent cross section for semi-inclusive deep-inelastic scattering, ep(up arrow) -> eDX. This is an extension of the similar formula known for the so-called soft-gluon-pole contribution induced by the quark-gluon correlation function in a variety of processes. Our master formula reduces the relevant interfering partonic subprocess with the participation of the three gluons to the Born cross sections for the gamma*g -> c (c) over bar scattering, which reveals the new structure behind the twist-3 single spin asymmetry and simplifies the actual calculation greatly. A possible extension to higher order corrections is also discussed.

DOI： 10.1103/PhysRevD.83.114014

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As a possible source of the single transverse-spin asymmetry, we study the contribution from purely gluonic correlation represented by the twist-3 "three-gluon correlation" functions in the transversely polarized nucleon. We first define a complete set of the relevant three-gluon correlation functions, and then derive its contribution to the twist-3 single-spin-dependent cross section for the D-meson production in semi-inclusive deep inelastic scattering, which is relevant to determine the three-gluon correlations. Our cross-section formula differs from the corresponding result in the literature, and the origin of the discrepancy is clarified. © 2010 The American Physical Society.

DOI： 10.1103/PhysRevD.82.054005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

We present a detailed study of the two-parton light-cone distribution amplitudes for 1(3)P(2) nonet tensor mesons. The asymptotic two-parton distribution amplitudes of twist-2 and twist-3 are given. The decay constants f(T) and f(T)(perpendicular to) T defined by the matrices of nonlocal operators on the light-cone are estimated using the QCD sum rule techniques. We also study the decay constants for f(2)(1270) and f(2)'(1525) based on the hypothesis of tensor meson dominance together with the data of Gamma(f(2) -> pi pi) and Gamma(f2' -> K (K) triple over dot and find that the results are in accordance with the sum rule predictions.

DOI： 10.1103/PhysRevD.82.054019

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

As a possible source of the single transverse-spin asymmetry, we study the contribution from purely gluonic correlation represented by the twist-3 "three-gluon correlation" functions in the transversely polarized nucleon. We first define a complete set of the relevant three-gluon correlation functions, and then derive its contribution to the twist-3 single-spin-dependent cross section for the D-meson production in semi-inclusive deep inelastic scattering, which is relevant to determine the three-gluon correlations. Our cross-section formula differs from the corresponding result in the literature, and the origin of the discrepancy is clarified.

DOI： 10.1103/PhysRevD.82.054005

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We analyze the single transverse-spin asymmetry (SSAs) for inclusive hadron production in the pp collision at RHIC based on the twist-3 mechanism in QCD. As an origin of SSAs, we take into account of all kinds of pole contributions associated with the twist-3 quark-gluon correlation functions in the polarized proton. By the inclusion of the soft-fermion-pole contribution in addition to the soft-gluon-pole contribution, we find SSAs observed at RHIC are better described for all kinds of mesons. P(T) dependence of the asymmetry and the comparison with the FNAL data are also presented.

DOI： 10.1103/PhysRevD.82.034009

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We study the single transverse spin asymmetry for the inclusive pion production in the nucleon-nucleon collision, p(up arrow)p ->pi X, based oil the twist-3 mechanism in the collinear factorization. We derive the soft-fermion-pole (SFP) contribution 10 the twist-3 single-spin-dependent cross section associated with the twist-3 quark-gluon correlation functions in the polarized nucleon. We find that the SFP can give rise to a large effect to the asymmetry A(N) owing to the large partonic hard cross sections with the large color factor, if the SFP function has a similar magnitude as the soft-gluon-pole (SGP) function. in spite of the absence of the "derivative term" for the SFP function unlike for the SGP function. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physletb.2009.04.017

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The longitudinal-transverse spin asymmetry A(LT) in the polarized Drell-Yan process depends on the twist-3 spin-dependent distributions of nucleon. In addition to the contributions expressed as matrix element of the twist-3 operators, these distributions contain the so-called Wandzura-Wilczek part, which is completely determined by a certain integral of the twist-2 spin-dependent parton distributions. We demonstrate that the recently obtained empirical information on the transversity distribution allows a realistic estimate of the Wandzura-Wilczek contribution to A(LT) for the case of polarized proton-antiproton collisions. In particular, our results in the Wandzura-Wilczek approximation indicate that rather large A(LT) can be observed in the proposed spin experiments at GSI, and its behavior as a function of dilepton mass obeys novel pattern, compared with the other double-spin asymmetries A(TT) and A(LL). Our results provide a guide for testing a signal of effects originating from the twist-3 operators associated with quark-gluon correlation. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physletb.2008.08.049

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DOI： 10.1016/j.physletb.2008.09.026

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Recent studies have shown that two widely-used mechanisms for single-transverse-spin asymmetries based on either twist-three contributions or on transverse-momentum-dependent (Sivers) parton distributions become identical in a kinematical regime of overlap. This was demonstrated for the so-called soft-gluon-pole and hard-pole contributions to the asymmetry associated with a particular quark-gluon correlation function in the nucleon. In this Letter, using semi-inclusive deep inelastic scattering as an example, we extend the study to the contributions by soft-fermion poles and by another independent twist-three correlation function. We find that these additional terms organize themselves in such a way as to maintain the mutual consistency of the two mechanisms for single-spin asymmetries. (C) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physletb.2007.11.096

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

We prove that a twist-3 soft-gluon-pole (SGP) cross section for single spin asymmetries is determined by a certain "primordial" twist-2 cross section up to kinematic and color factors in the leading order perturbative QCD. In particular, for the processes in which the partonic hard scattering occurs among massless partons, the invariance of the primordial partonic cross section under scale transformation leads to remarkable simplification of the SGP cross section, reproducing the compact form that was recently observed for pion production p(up arrow)p ->pi X and direct-photon production p(up arrow)p ->gamma X.

DOI： 10.1103/PhysRevD.76.011502

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Perturbative QCD relates the single transverse-spin asymmetries (SSAs) for hard processes at large transverse-momentum of produced particle to partonic matrix elements that describe interference between scattering from a coherent quark-gluon pair and from a single quark, generated through twist-3 quark-gluon correlations inside a hadron. When the coherent gluon is soft at the gluonic poles, its coupling to partonic subprocess can be systematically disentangled, so that the relevant interfering amplitude can be derived entirely from the Born diagrams for the scattering from a single quark. We establish a new formula that represents the exact rules to derive the SSA due to soft-gluon poles from the knowledge of the twist-2 cross-section formula for unpolarized processes. This single master formula is applicable to a range of processes like Drell-Yan and direct-photon production, and semi-inclusive deep inelastic scattering, and is also useful to manifest the gauge invariance of the results. (c) 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physletb.2007.01.044

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We study the single spin asymmetry (SSA) for the pion production in semi-inclusive deep inelastic scattering, ept up arrow -> e pi X, in the framework of the collinear factorization. We derive the complete cross section formula associated with the twist-3 quark-gluon correlation functions for the transversely polarized nucleon, including all types of pole (hard-pole, soft-fermion-pole and soft-gluon-pole) contributions which produce the strong interaction phase necessary for SSA. We prove that the partonic hard pan from each pole contribution satisfies certain constraints from Ward identities for color gauge invariance. We demonstrate that the use of these new constraints is crucial to reorganize the collinear expansion of the Feynman diagrams into manifestly gauge-invariant form so as to obtain the factorization formula for the cross section in terms of a complete set of the twist-3 distributions without any double counting. It also provides a simpler method for the actual calculation. We also present a simple estimate of SSA based on our cross section formula, using a model for the "soft-gluon-pole function" that represents the relevant twist-3 quark-gluon correlation, and compare the magnitude of the terms involving the derivative of the soft-gluon-pole function with that of the "nonderivative" terms. (C) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nuclphysb.2006.11.016

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We study the single spin asymmetry (SSA) for the pion production with large transverse momentum PT in semi-inclusive deep inelastic scattering ep up arrow -> e pi X. We derive the twist-3 cross section formula for SSA, focussing on the soft-gluon-pole contributions associated with the twist-3 distribution for the nucleon and with the twist-3 fragmentation function for the pion. We present a simple estimate of the asymmetries due to each twist-3 effect from nucleon and pion, respectively, by fixing the overall strength of the relevant nonperturbative quantities by the data on the SSA A(N) in p up arrow p -> pi X collision. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nuclphysb.2006.05.036

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We study the transverse-momentum distribution of hadrons produced in semi-inclusive deep-inelastic scattering (SIDIS). We consider cross sections for various combinations of polarizations of the initial lepton and nucleon or the produced hadron, for which we perform the resummation of large double-logarithmic perturbative corrections arising at small transverse momentum. We present phenomenological results for the processes lp -> l pi X with longitudinally polarized leptons and protons. We discuss the impact of the perturbative resummation and of estimated non-perturbative contributions on the corresponding cross sections and their spin asymmetry. Our results should be relevant for ongoing studies in the COMPASS experiment at CERN, and for future experiments at the proposed eRHIC collider at BNL. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nuclphysb.2006.03.009

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We study the twist-2 double-spin asymmetries for the 2-jets and large-p(T) hadron (pi, Lambda, etc.) production in semi-inclusive deep inelastic scattering to O(alpha(S)) in perturbative QCD. After deriving the complete set of the polarized cross-section which is differential with respect to the transverse momentum, we discuss characteristic features of the azymuthal spin asymmetries, using existing parton densities and fragmentation functions at COMPASS and EIC energies. (C) 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0550-3213(03)00259-1

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Single transverse spin asymmetry for the pion production in pp and ep collisions is studied in the framework of collinear factorization. The soft-gluon pole contributions with twist-3 distribution and fragmentation functions are identified and its characteristic features are discussed.

DOI： 10.1016/S0375-9474(03)01070-4

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Sum rules for twist-3 distributions are reexamined. Integral relations between twist-3 and twist-2 parton distributions suggest the possibility for a δ-function at x = 0. We confirm and clarify this result by constructing hL and hL3 (quark-gluon interaction dependent part of hL) explicitly from their moments for a one-loop dressed massive quark. The physics of these results is illustrated by calculating hL(x, Q2) using light-front time-ordered pQCD to O(αS) on a quark target. A δ(x) term is also found in e(x, Q2), but not in gT(x, Q2), to this order in O(αS). © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0550-3213(02)00263-8

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Polarization of the A hyperon produced with a large transverse momentum in unpolarized nucléon-nucléon collisions is analyzed in the framework of QCD factorization. We focus on the mechanism in which the soft-gluon component of the chiral-odd spin-independent twist-3 quark distribution EF(x,x) becomes a source of the polarized quark fragmenting into the polarized A. Our simple model estimate for this contribution indicates that it gives rise to a significant A polarization at large XF. This is in parallel with the observation that the soft gluon pole mechanism gives rise to a large single transverse spin asymmetry in pion production at xr→1. ©2001 The American Physical Society.

DOI： 10.1103/PhysRevD.64.034019

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We present an estimate of a chiral-odd contribution to the single transverse spin asymmetry in the large-p(T) pion production in the nucleon-nucleon collision. In this contribution the transversity distribution and the chiral-odd spin-independent twist-3 distribution appear. Because of the smallness of the corresponding hard cross section, this term turned out to be negligible in all kinematic regions compared with the chiral-even contribution. (C) 2000 Elsevier Science B.V.

DOI： 10.1016/S0370-2693(00)00969-2

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arXiv

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

We present a leading order (LO) estimate for the longitidinal-transverse spin<br />
asymmetry (A_{LT}) in the nucleon-nucleon polarized Drell-Yan process at RHIC<br />
and HERA-$\vec{N}$ energies in comparison with A_{LL} and A_{TT}. A_{LT}<br />
receives contribution from g_1, the transversity ditribution h_1, and the<br />
twist-3 distributions g_T and h_L. For the twist-3 contribution we use the bag<br />
model prediction evolved to a high energy scale by the large-N_c evolution<br />
equation. We found that A_{LT} (normalized by the asymmetry in the parton<br />
level) is much smaller than the corresponding A_{TT}. Twist-3 contribution<br />
given by the bag model also turned out to be negligible.

DOI： 10.1016/S0375-9474(00)00075-0

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arXiv

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A formula for the single transverse spin asymmetry in the large-$p_T$ pion<br />
production in the nucleon-nucleon collision is derived. We focuss on the<br />
chiral-odd contribution where the transversity distribution and the chiral-odd<br />
spin-independent twist-3 distribution contributes. This contribution is<br />
expected to give rise to a large effect at $x_F\to -1$.

DOI： 10.1016/S0370-2693(00)00261-6

arXiv

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

How confinement of quarks is implemented for multi-hadron systems in the quark cluster model is reviewed. In order to learn the nature of the confining interaction for fermions we first study 1+1 dimensional QED and QCD, in which the gauge field can be eliminated exactly and generates linear interaction of fermions. Then, we compare the two-body potential model, the flip-flop model and the Born-Oppenheimer approach in the strong coupling lattice QCD for the meson-meson system. Having shown how the long-range attraction between hadrons, van der Waals interaction, shows up in the two-body potential model, we discuss two distinct attempts beyond the two-body potential model: one is a many-body potential model, the flip-flop model, and the other is the Born-Oppenheimer approach in the strong coupling lattice QCD. We explain how the emergence of the long-range attraction is avoided in these attempts. Finally, we present the results of the application of the flip-flop model to the baryon-baryon scattering in the quark cluster model.

Web of Science

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

Two twist-3 processes are discussed. We first present a simple estimate of the longitudinal-transverse spin asymmetry in the polarized Drell-Yan process. We next derive a cross section for the semi-inclusive production of a polarized spin-1/2 baryon in the DIS of an unpolarized electron off the polarized nucleon.

DOI： 10.1016/S0920-5632(99)00803-8

Scopus

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

We present the one-loop anomalous dimension matrices for the chiral-even twist-3 (nonsinglet) conformal operators, which govern the scale-dependence of the vector meson light-cone wave functions through the conformal expansion. It is clarified that the constraints from the charge-conjugation invariance and the chirality conservation allow only one independent anomalous dimension matrix for each conformal spin. © 1998 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0370-2693(98)00901-0

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arXiv

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

We present a systematic study of twist 3 light-cone distribution amplitudes of vector mesons in QCD, which is based on conformal expansion and takes into account meson and quark mass corrections. A complete set of distribution amplitudes is constructed for p, ω, K* and φ mesons, which satisfies all (exact) equations of motion and constraints from conformal expansion. Non-perturbative input parameters are calculated from QCD sum rules, including an update of SU(3) breaking corrections in the leading twist distributions. © 1998 Elsevier Science B.V.

DOI： 10.1016/S0550-3213(98)00356-3

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arXiv

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

We present a leading order (LO) estimate for the longitudinal-transverse spin asymmetry (ALT) in the nucleon-nucleon polarized Drell-Yan process at RHIC and HERA-N→ energies in comparison with ALL and ATT. ALTreceives contribution from g1, the transversity distribution h1, and the twist-3 distributions gT and hL. For the twist-3 contribution we use the bag model prediction evolved to a high energy scale by the large-Nc evolution equation. We found that ALT (normalized by the asymmetry in the parton level) is much smaller than the corresponding ATT. Twist-3 contribution given by the bag model also turned out to be negligible. © 1998 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0370-2693(98)00516-4

Scopus

arXiv

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Publishing type：Research paper (scientific journal)  

We present a calculation of the two-loop anomalous dimension for the<br />
transversity distribution h_1(x,Q^2), $\gamma^{h(1)}_n$, in the MS scheme of<br />
the dimensional regularization. Due to the chiral-odd nature, h_1 does not mix<br />
with the gluon distributions, and thus our result is the same for the<br />
flavor-singlet and nonsinglet distributions. At small n (moment of h_1),<br />
$\gamma^{h(1)}_n$ is significantly larger than $\gamma^{f(1)}_n$ (the anomalous<br />
dimension for the nonsinglet f_1), but approaches $\gamma^{f(1)}_n$ very<br />
quickly at large n, keeping the relation $\gamma^{h(1)}_n &gt; \gamma^{f(1)}_n$.<br />
This feature is in parallel to the relation between the one-loop anomalous<br />
dimension for f_1 and h_1.

DOI： 10.1103/PhysRevD.56.7350

arXiv

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

We study the Q2 evolution of the nucleon's chiral-odd twist-3 distribution hL(x, Q2) starting from the MIT bag model calculation. A simple GLAP equation for hL(x, Q2) obtained at large Nc is used for the Q2 evolution. The correction due to the finite value of Nc is O(1/N2 c) ∼ 10 % level. It turns out that the twist-3 contribution to hL(x, Q2) is significantly reduced at Q2 = 10 GeV2 in contrast to the g2(x, Q2) case. This is due to the fact that the corresponding anomalous dimension for hL is larger than that for g2 at small n (spin). © 1997 Elsevier Science B.V.

DOI： 10.1016/S0370-2693(97)00524-8

Scopus

arXiv

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Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevd.55.3068

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevD.55.3068/fulltext

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Yukawa Institute for Theoretical Physics  

A new QCD sum rule analysis on the spin-isospin averaged ρ, ω and φ meson-nucleon scattering lengths is presented. By introducing the constraint relation on the low energy limit of the vector-current nucleon forward scattering amplitude (low energy theorem), we obtain aρ = -0.47±0.05 fm, aω = -0.41±0.05 fm and aφ, = -0.15±0.02 fm, which suggests that these V-N interactions are attractive. It is also proved that previous studies on the mass shift of these vector mesons in the nuclear medium are essentially those obtained from these scattering lengths in the linear density approximation.

DOI： 10.1143/PTP.98.631

Scopus

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Language：English   Publishing type：Research paper (scientific journal)  

We prove that the twist-3 chiral-odd parton distributions obey simple Gribov-Lipatov-Altarelli-Parisi evolution equations in the limit N-c --&gt
infinity and give analytic results for the corresponding anomalous dimensions. To this end we introduce an evolution equation for the corresponding three-particle twist-3 parton correlation functions and find an exact analytic solution. For large values of n (operator dimension) we are further able to collect all corrections subleading in N-c, so our final results are valid io O((1/N-c(2))ln(n)/n) accuracy. © 1996 The American Physical Society.

DOI： 10.1103/PhysRevLett.77.3078

Scopus

arXiv

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMERICAN PHYSICAL SOC  

Web of Science

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevD.47.1225

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevD.48.2313

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Publishing type：Research paper (scientific journal)  

The QCD sum rule method is applied to derive a formula for the rho, omega,<br />
phi meson-nucleon spin-isospin-averaged scattering lengths<br />
$a_{\rho,\omega,\phi}$. We found that the crucial matrix elements are<br />
$\langle\bar{q}\gamma_\mu D_\nu q\rangle_N$ ($q=u,d$) (twist-2 nucleon matrix<br />
element) for $a_{\rho,\omega}$ and $m_s\langle\bar{s}s\rangle_N$ for $a_\phi$,<br />
and obtained $a_\rho =0.14\pm 0.07$ fm, $a_\omega =0.11\pm 0.06$ fm and $a_\phi<br />
=0.035\pm 0.020$ fm. These small numbers originate from a common factor<br />
$1/(m_N+m_{\rho,\omega,\phi})$. Our result suggests a slight increase ($&lt; 60$<br />
MeV for $\rho$, $\omega$, and $&lt;15$ MeV for $\phi$) of the effective mass of<br />
these vector mesons in the nuclear matter (in the {\it dilute} nucleon gas<br />
approximation). The origin of the discrepancy with the previous study was<br />
clarified.

DOI： 10.1103/PhysRevC.51.1488

arXiv

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

A new formulation of QCD sum rules at finite temperature (T) is developed. Because of the factorization in the operator product expansion, all the soft dynamics including the effect of finite T in the hadronic phase is taken into account in the thermal average of local operators [O]T. Unlike for the T = 0 case, [O]T has non-vanishing values for the Lorentz non-scalar operators such as qgamma(mu)D(nu)qBAR. On the basis of the observation that the finite-temperature medium can be well approximated by a dilute (non-interacting) pion gas at low T, one can make a sensible estimate of the T-dependence of various condensates, where the current algebra and the experimental information of the pion structure functions turn out to be a useful guide. We applied this method to the light vector mesons (rho, omega and A1) and found that the change of the four-quark condensate at T not-equal 0 is crucial to the change of meson properties. The lepton pair production rate from the hot hadronic medium near the rho-resonance is calculated using the result of the sum rules. This has direct relevance to the detection of the lepton pairs in future projects of the ultra-relativistic heavy-ion collisions such as RHIC and LHC.

Web of Science

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Publishing type：Research paper (scientific journal)  

We analyse the recent precision measurements of the lepton-hadron deep<br />
inelastic scattering at CERN and SLAC to extract model independent constraints<br />
among the nucleon matrix elements of the twist-4 operators. We also study a<br />
parameterization of these matrix elements and point out the possibility that<br />
the matrix elements of the quark-gluon mixed operator has a negative value of<br />
the order of $- (400 \pm 100\ {\rm MeV})^2$ at 5 GeV$^2$ renormalization scale.

DOI： 10.1016/0370-2693(93)91092-2

arXiv

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevD.45.3237

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1142/S0217751X91000666

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

A full QCD simulation was carried out for the spin-dependent force for the heavy quark spectroscopy using the Kogut-Susskind quark action with the gauge coupling β=5.6 on a 103×20 lattice at mqa=0.1 and 0.05. The effect of vacuum quark loops on the spin-dependent potential is absorbed into the shift of the bare gauge coupling. This implies that the spin-dependent potential would be still insufficient to describe the excited spectra of J/Ψ and Υ{hooked} families in terms of the non-relativistic potential model, contrary to the conjecture sometimes made in the literature. The present result ensures that the inclusion of the vacuum quark loop does not affect the mass splitting patterns of hadron multiplets in the quenched calculation. © 1989.

DOI： 10.1016/0370-2693(89)91392-0

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Language：English   Publishing type：Research paper (scientific journal)  

We present a Langevin simulation of the hadron mass spectrum with the three-flavor Kogut-Susskind quark action for the quark masses, mqa = 0.05 and 0.1 at β=5.6 on a 103×20 and an 83×18 lattice. The effects of the vacuum quark loops were found to be absorbable into the shift of the coupling, and hence a large mN/mρ{variant} still holds. Our analysis shows that at β=5.6 the system with N=8 passes through the critical point for finite size ("finite temperature") effects between mqa=0.05 and 0.1, and the N=10 system is always in the confined phase for mqa≥0.05. © 1998.

DOI： 10.1016/0370-2693(88)91299-3

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Language：English   Publishing type：Research paper (scientific journal)  

A lattice-QCD formalism for the calculation of spin-dependent potentials for heavy-quark systems is developed and applied to quark-antiquark (Q-Q») and quark-diquark (Q-Q2) systems by use of the Monte Carlo technique. The tensor and the spin-spin terms of the potential are found to be consistent with the perturbative gluon-exchange potential. The magnitude of the Q-Q» potential is 2 times larger than that of the Q-Q2 potential, whcih can be associated with the color factor in a meson and a baryon. © 1987 The American Physical Society.

DOI： 10.1103/PhysRevLett.59.962

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Language：English   Publishing type：Research paper (scientific journal)  

The effects of the interaction among quarks in the hidden color configuration in the flip-flop model of confinement are studied for two-nucleon systems. The hidden color component in the wave function is found to play an important role. The model with a weak hidden-color confinement is shown to explain the medium-range attraction of the nuclear force. In such a model, nucleons expand appreciably in the overlapping region. © 1986.

DOI： 10.1016/0370-2693(86)90487-9

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Language：English   Publishing type：Research paper (scientific journal)  

The baryon-baryon interaction with a new type of confinement potential (a flip-flop model) free from the pathology of the color van der Waals force is studied in the framework of the quark-cluster model in the case of color SU(2). For moderate values of the parameter describing the confinement of the "hidden-color" part, the confinement potential turns out not to contribute to the scattering so much. The Galilei-invariant part of the spin-orbit interaction arising as a relativistic effect from the confinement potential is also studied in comparison with the one from the OGEP. The former does not contribute significantly between baryons even if its strength is determined so as to cancel the latter in the excited state of a single baryon, which suggests the possibility that the latter is an important source of the baryon-baryon spin-orbit interaction. Similar results are expected for the more realistic case of color SU(3). © 1986.

DOI： 10.1016/0375-9474(86)90325-8

Scopus

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Language：English   Publishing type：Research paper (scientific journal)  

The nucleon-nucleon interaction with a flip-flop confining interaction which is free from the pathology of the color van der Waals force is studied in the framework of the quark cluster model supplemented by an effective meson-exchange potential (EMEP). The experimental phase shifts for spin-singlet states (1S0, 1P1, 1D2) are well reproduced. The spin-orbit interaction from the confinement potential is also studied and compared with the one from the one-gluon exchange potential (OGEP). The strength of the former is determined so that it cancels the latter in the excited states of a nucleon. The cancellation does not occur in the NN interaction and the resulting spin-orbit force including both contributions has roughly the required strength for the 3P and 3D channels. This fact suggests the possibility that the substantial part of the NN spin-orbit force can be attributed to the quark contribution. © 1986.

DOI： 10.1016/0375-9474(86)90102-8

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)   Publisher：Journal of the Physical Society of Japan  

DOI： 10.7566/jpscp.26.021016

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Publisher：Sissa Medialab  

DOI： 10.22323/1.346.0192

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Language：English  

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Language：English  

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Language：English   Publisher：Sissa Medialab  

DOI： 10.22323/1.265.0220

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Language：English  

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Publishing type：Internal/External technical report, pre-print, etc.  

We present our recent analysis on the transverse single-spin asymmetry (SSA)<br />
in inclusive pion and direct-photon production in pp collisions for RHIC<br />
kinematics. The analysis includes the contributions from twist-3<br />
quark-gluon-quark correlations in the proton and twist-3 fragmentation effects<br />
for the pion. Some of the functions appearing in the formula for the SSA, such<br />
as the soft-gluon-pole Qiu-Sterman function, the nucleon transversity, and the<br />
Collins function were fixed consistently with the SSA data in semi-inclusive<br />
DIS and in e+e- annihilation, so that our analysis is free from the sign<br />
mismatch problem.

DOI： 10.1155/2015/257934

arXiv

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Language：English   Publisher：SPRINGER WIEN  

We present a new collinear twist-3 analysis of the transverse SSA A (N) at RHIC. We use the TMD Sivers/Collins function to fix some of the relevant collinear twist-3 functions and perform a fit of the RHIC data with other parameterized twist-3 functions. This allows us to keep the consistency among descriptions in pp collision, SIDIS, and e (+) e (-) annihilation and thus could provide a unified description of the spin asymmetries in the low- and high-P (T) processes. By taking into account the twist-3 fragmentation contribution, we show for the first time this contribution could be the main source of A (N) in and its inclusion could provide a solution for the sign-mismatch problem.

DOI： 10.1007/s00601-014-0913-4

Web of Science

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Language：English   Publisher：E D P SCIENCES  

We review and give an update on the current status of what causes transverse single-spin asymmetries (TSSAs) in semi-inclusive processes where a single hadron is detected in the final state, especially those involving proton-proton (pp) collisions. In particular, we provide a new analysis within collinear factorization of TSSAs in high transverse momentum charged and neutral pion production in pp collisions at the Relativistic Heavy Ion Collider (RHIC). This study incorporates the so-called twist-3 fragmentation term and shows that one can describe RHIC data through this mechanism. Moreover, by fixing other non-perturbative inputs through extractions of transverse momentum dependent functions in e(+)e(-) -&gt; h(1)h(2)X and semi-inclusive deep-inelastic scattering (SIDIS), we provide for the first time a consistency between certain spin/azimuthal asymmetries in all three reactions (i.e., pp, e(+)e(-), and SIDIS).

DOI： 10.1051/epjconf/20158502013

Web of Science

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Language：English   Publisher：E D P SCIENCES  

We study the twist-3 three-gluon contribution to the single spin asymmetry in the light-hadron production in pp collision in the framework of the collinear factorization. We derive the corresponding cross section formula in the leading order with respect to the QCD coupling constant. We also present a numerical calculation of the asymmetry at the RHIC energy, using a model for the three-gluon correlation functions suggested by the asymmetry for the D-meson production at RHIC. We found that the asymmetries for the light-hadron and the jet productions are very useful to constrain the magnitude and form of the correlation functions. Since the three-gluon correlation functions shift the asymmetry for all kinds of hadrons in the same direction, it is unlikely that they become a main source of the asymmetry.

DOI： 10.1051/epjconf/20158502012

Web of Science

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)  

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Language：English   Publisher：MAIK NAUKA/INTERPERIODICA/SPRINGER  

We study the contribution of the collinear twist-3 quark-gluon correlation to the single transversespin asymmetry in direct-photon and single-jet productions in pp collision. At typical RHIC kinematics we find sizable asymmetries in the forward region of the polarized nucleon while they are almost zero in the backward region. We also find the soft-fermion pole contribution is vanishingly small, suggesting the measurement of these asymmetries provides us with an unique opportunity to determine the net soft-gluon pole function.

DOI： 10.1134/S1063779614010456

Web of Science

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)  

We study the contribution of the twist-3 fragmentation function to the single<br />
transverse-spin asymmetry in SIDIS within the framework of the collinear<br />
factorization. Using the Ward-Takahashi identity in QCD, we establish the<br />
collinear twist-3 formalism in the Feynman gauge to calculate its non-pole<br />
contribution to the asymmetry.

arXiv

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Language：English   Publisher：Editrice Compositori s.r.l.  

We study the single transverse-spin asymmetry for the inclusive direct-photon and single-jet productions in the proton-proton collision based on the twist-3 mechanism in the collinear factorization. Taking into account all the effects from the twist-3 quark-gluon correlation functions inside a transversely polarized proton, we present a prediction for the asymmetries at the typical RHIC kinematics. In both processes we find sizable asymmetries in the forward region of the polarized proton while they are almost zero in the backward region. This implies that if one finds a nonzero asymmetry in the backward region in these processes, it should be ascribed wholely to the three-gluon correlations. © Società Italiana di Fisica.

DOI： 10.1393/ncc/i2013-11581-7

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Language：English   Publisher：Editrice Compositori s.r.l.  

We study the single-spin asymmetries for the D-meson production, Drell-Yan lepton-pair production and the direct-photon production in the pp collision induced by the twist-3 three-gluon correlation functions in the transversely polarized nucleon. We present a corresponding polarized cross section formula in the leading-order with respect to the QCD coupling and a model calculation for the asymmetries, illustrating the sensitivity to the form of the correlation functions. © Societa Italiana di Fisica.

DOI： 10.1393/ncc/i2012-11185-9

Web of Science

Scopus

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Language：English   Publisher：IOP PUBLISHING LTD  

We study the single spin asymmetry (SSA) for the D-meson production A(N)(D) in the pp collision, p(up arrow)p -&gt; DX, in the framework of the collinear factorization. Since the charm quark is mainly produced through the c (c) over bar -pair creation from the gluon-fusion process, this is an ideal process to probe the twist-3 triple-gluon correlation functions in the polarized nucleon. We derive the corresponding cross section formula for the contribution of the triple-gluon correlation function to A(N)(D) in p(up arrow)p -&gt; DX, applying the method developed for ep(up arrow) -&gt; eDX in our previous study. As in the case of ep(up arrow) -&gt; eDX, our result differs from a previous study in the literature. We will also present a simple estimate of the triple-gluon correlation functions based on the preliminary data on A(N)(D) by RHIC.

DOI： 10.1088/1742-6596/295/1/012083

Web of Science

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Language：English   Publisher：IOP PUBLISHING LTD  

We present a new analysis for the single-transverse spin asymmetry (SSA) for the inclusive pion and kaon productions in the proton-proton collisions measured at RHIC. The framework we use is the collinear factorization in which SSA appears as a twist-3 observable resulting from the multiparton correlations in the hadrons. As a relevant multiparton correlation, we include all the contributions associated with the quark-gluon correlation functions in the transversely polarized proton, i.e., those from the soft-gluon-pole (SGP) and the soft-fermion-pole (SFP). We have found that the SGP contribution alone is insufficient to describe the observed RHIC A(N) data and the inclusion of the SFP contribution plays an important role for the improved description of the data. In particular, P-T-dependence of A(N) and A(N) for K- have been well described in our new analysis.

DOI： 10.1088/1742-6596/295/1/012059

Web of Science

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Language：English   Publisher：AMER INST PHYSICS  

We study the single spin asymmetry for the D-meson production, Drell-Yan lepton-pair production and the direct-photon production in the pp collision induced by the twist-3 three-gluon correlation functions in the transversely polarized nucleon. We present a corresponding polarized cross section formula in the leading-order with respect to the QCD coupling and a model calculation for the asymmetries, illustrating the sensitivity to the form of the correlation functions.

DOI： 10.1063/1.3667308

Web of Science

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Language：English   Publisher：IOP PUBLISHING LTD  

We study the single spin asymmetry (SSA) induced by purely gluonic correlation inside a nucleon, in particular, by the three-gluon correlation functions in the transversely polarized nucleon, p(up arrow). This contribution is embodied as a twist-3 mechanism in the collinear factorization framework and controls the SSA to be observed in the D-meson production with large transverse-momentum in semi-inclusive DIS (SIDIS), ep(up arrow) -&gt; eDX. We define the relevant three-gluon correlation functions in the nucleon, and determine their complete set at the twsit-3 level taking into account symmetry constraints in QCD. We derive the single-spin-dependent cross section for the D-meson production in SIDIS, taking into account all the relevant contributions at the twist-3 level. The result is obtained in a manifestly gauge-invariant form as the factorization formula in terms of the three-gluon correlation functions and reveals the five independent structures with respect to the dependence on the azimuthal angle for the produced D meson. We also demonstrate the remarkable relation between the twist-3 single-spin-dependent cross section and twist-2 cross sections for the D-meson production, as a manifestation of universal structure behind the SSA in a variety of hard processes.

DOI： 10.1088/1742-6596/295/1/012082

Web of Science

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Language：English   Publisher：AMER INST PHYSICS  

Single spin asymmetry (SSA) is a twist-3 observable in the collinear factorization approach. We present a twist-3 single-spin-dependent cross section formula for the pion production in pp-collision, p(up arrow)p -&gt; pi X, relevant to RHIC experiments. In particular, we calculate the soft-fermion-pole (SFP) contribution to the cross section from the quark-gluon correlation functions. We show that its effect can be as large as the soft-gluon-pole (SGP) contribution owing to the large SFP partonic hard cross section, even though the derivative of the SFP function does not participate in the cross section.

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Language：English   Publisher：AMER INST PHYSICS  

We derive the complete twist-3 single-spin-dependent cross section for semi-inclusive DIS, ep(up arrow) -&gt; e pi X, associated with the complete set of the twist-3 quark-gluon correlation functions in the transversely polarized nucleon, extending our previous study. The cross section consists of five independent structure functions with different azimuthal dependences, consistently with the transverse-momentum-dependent (TMD) factorization approach in the low q(T) region. Correspondence with the inclusive DIS limit and comparison with the TMD approach are briefly discussed.

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Language：English   Publisher：AMER INST PHYSICS  

The longitudinal-transverse spin asymmetry A(LT) in the polarized Drell-Yan process depends on twist-3 quark distributions of nucleon. In addition to the contributions associated with the twist-3 operators, these distributions contain the "Wandzura-Wilczek (VAV)" part, which is determined by a certain integral of twist-2 distributions. The recently obtained empirical information on the ft-ansversity allows a realistic estimate of the WW contribution to A(LT) for the polarized p (p) over bar collisions. Our results indicate that rather large A(LT) (similar to 10%) can be observed in the proposed spin experiments at GSI, with novel pattern as a function of dilepton mass compared with A(TT) and A(LL).

DOI： 10.1063/1.3215697

Web of Science

arXiv

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Language：English   Publisher：AMER INST PHYSICS  

A dominant QCD mechanism for the single transverse-spin asymmetry in hard processes is induced by the twist-3 quark-gluon correlations inside nucleon, combined with the soft-gluonic poles to produce the interfering phase for the associated partonic hard scattering. It is shown that the corresponding interfering amplitude can be calculated entirely in terms of the partonic Born cross section which participates in the twist-2 cross section formula for the spin-averaged process.

DOI： 10.1063/1.2750840

Web of Science

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Language：English   Publisher：AMER INST PHYSICS  

Establishing the twist-3 formalsim for the single transverse spin asymmetry, we present a complete single-spin-dependent cross section for SIDIS, ep(up arrow) -&gt; e pi X, associated with the twist-3 distribution for the transversely polarized nucleon. We emphasize that the consistency condition from the Ward identifies for color gauge invariance is crucial to prove factorization property of the cross section.

DOI： 10.1063/1.2750836

Web of Science

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Language：English   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

We study the transverse-momentum distribution of hadrons produced in semi-inclusive deep-inelastic scattering. We consider cross sections for various combinations of the polarizations of the initial lepton and nucleon or the produced hadron, for which we perform the resummation of large double-logarithmic perturbative corrections arising at small transverse momentum. We present phenomenological results for the process ep -&gt; e pi X for the typical kinematics in the COMPASS experiment. We discuss the impact of the perturbative resummation and of estimated non-perturbative contributions on the corresponding cross Sections and their spin asymmetry.

DOI： 10.1142/9789812706706_0183

Web of Science

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：日本物理学会  

DOI： 10.11316/butsuri1946.60.534

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Language：English   Publisher：AMER INST PHYSICS  

Cross section formulas for the single spin asymmetry in pup arrowp --&gt; pi(l(T))X and epup arrow --&gt; pi(l(T))X are derived and its characteristic features are discussed.

Web of Science

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Language：English   Publisher：AMER INST PHYSICS  

Cross section formulas for the Lambda polarization in pp --&gt; Lambda(up arrow)(l(T))X and ep --&gt; Lambda(up arrow)(l(T))X are derived and its characteristic features are discussed.

Web of Science

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Language：English   Publishing type：Internal/External technical report, pre-print, etc.   Publisher：AMER INST PHYSICS  

A QCD formula for the polarization in the large-p(T) Lambda hyperon production in the unpolarized nucleon-nucleon collision at large x(F) is derived. We focus on the mechanism in which the chiral-odd spin-independent twist-3 quark distribution E-F(x, x) becomes the source of the transversely polarized quarks fragmenting into the polarized Lambda. A simple model estimate for that contribution shows the possibility that it gives rise to a sizable Lambda polarization.

DOI： 10.1063/1.1384108

Web of Science

arXiv

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：Japan Physical Society  

DOI： 10.11316/butsuri1946.53.438

CiNii Article

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Publishing type：Internal/External technical report, pre-print, etc.  

We present a calculation of the two-loop anomalous dimension for the<br />
transversity distribution $h_1(x,Q^2)$, $\gamma^{h(1)}_n$, in the MS scheme of<br />
the dimensional regularization. Because of the chiral-odd nature, $h_1$ does<br />
not mix with the gluon distributions, and thus our result is the same for the<br />
flavor-singlet and nonsinglet distributions. At small $n$ (moment of $h_1$),<br />
$\gamma^{h(1)}_n$ is significantly larger than $\gamma^{f,g(1)}_n$ (the<br />
anomalous dimension for the nonsinglet $f_1$ and $g_1$), but approaches<br />
$\gamma^{f,g(1)}_n$ very quickly at large $n$, keeping the relation<br />
$\gamma^{h(1)}_n &gt; \gamma^{f,g(1)}_n$. This feature is in parallel to the<br />
relation between the one-loop anomalous dimension for $f_1$ $(g_1)$ and $h_1$.<br />
We also show that this difference in the anomalous dimension between $h_1$ and<br />
$g_1$ leads to a drastic difference in the $Q^2$-evolution of those<br />
distributions in the small $x$ region.

arXiv

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Publishing type：Internal/External technical report, pre-print, etc.  

We discuss the $Q^2$ dependence of the chiral-odd twist-3 distribution<br />
$e(x,Q^2)$. The anomalous dimension matrix for the corresponding twist-3<br />
operators is calculated in the one-loop level. This study completes the<br />
calculation of the anomalous dimension matrices for all the twist-3<br />
distributions together with the known results for the other twist-3<br />
distributions $g_2(x,Q^2)$ and $h_L(x,Q^2)$. We also have confirmed that in the<br />
large $N_c$ limit the $Q^2$-evolution of $e(x,Q^2)$ is wholely governed by the<br />
lowest eigenvalue of the anomalous dimension matrix which takes a very simple<br />
analytic form as in the case of $g_2$ and $h_L$.

arXiv

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Language：English   Publisher：KYOTO UNIV  

We investigate the Q(2)-evolution of the chiral-odd spin-dependent parton distribution h(L)(x, Q(2)) relevant for the polarized Drell-Yan processes. The results are obtained in the leading logarithmic order in the framework of the renormalization group and the standard QCD perturbation theory. We calculate the anomalous dimension matrix for the twist-3 operators for h(L) in the one-loop order. The operator mixing among the relevant twist-3 operators including the operators proportional to the QCD equations of motion is treated properly in a consistent scheme. Implications for future experiments are also discussed.

DOI： 10.1103/PhysRevD.51.6125

Web of Science

arXiv

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Language：English   Publisher：Soryushiron Kenkyu  

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Venue：Brookhaven National Laboratory  

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Venue：DESY, Zeuthen, Germany  

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Venue：Veli Lošinj, Croatia  

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Venue：Cairns, Australia  

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Venue：Brookhaven National Laboratory, Upton, New York, USA  

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Venue：Institute for Nuclear Theory, university of Washington, Seattle, USA  

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Venue：Brookhaven National Laboratory, Upton, New York, USA  

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Venue：KEK  

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Venue：ハワイ島，Hilton Waikoloa  

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Venue：Yamagata  

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Venue：Lawrence Berkeley National Laboratory, Berkeley, California, USA  

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Venue：ECT*, Trento, Italy  

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Venue：Beijing University, China  

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Venue：University of British Columbia, Vanvouver, Canada  

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Venue：KEK  

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