The shear viscosity of a chemically equilibrating quark-gluon plasma at finite baryon density

Na-Na, Guan; Jia-Li, Long; Ma, Yugang; Yuan, Ying

doi:10.1209/0295-5075/103/52001

Cited by 15 publications

(31 citation statements)

References 33 publications

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“…The large size of the observed SSAs for single inclusive hadron production came as a big surprise and, a priori, posed a challenge for QCD, as the naive parton model predicts the asymmetries are proportional to the quark mass [2,3] and thus very small. During the past few decades, the remarkable theoretical progress was achieved by going beyond the naive parton model and following mainly two approaches: one approach is based on transverse momentum dependent(TMD) factorization [4,5] and the other on collinear twist-3 factorization [6][7][8][9][10]. In TMD factorization, naive time reversal odd TMD distributions and fragmentation function, known as the quark/gluon Sivers functions [4] and the Collins fragmentation function [5] can account for the large SSAs, while in the collinear twist-3 approach, the SSAs arise from twist-3 quark gluon correlator so-called Efremov-Teryaev-Qiu-Sterman function (ETQS) [6,7], tri-gluon correlation functions [8,9], and twist-3 collinear fragmentation functions [10].…”

Section: Introductionmentioning

confidence: 99%

Transverse single spin asymmetries at smallxand the anomalous magnetic moment

Zhou

2014

Phys. Rev. D

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We show that in the Mclerran-Venugopalan model, an axial asymmetrical valence quark distributions in the transverse plane of a transversely polarized proton can give rise to a spin dependent odderon. Such polarized odderon is responsible for the transverse single spin asymmetries(SSAs) for jet production in the backward region of pp collisions and open charm production in semi-inclusive DIS process.

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Section: Introductionmentioning

confidence: 99%

Transverse single spin asymmetries at smallxand the anomalous magnetic moment

Zhou

2014

Phys. Rev. D

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“…The derivative term contribution to A N in pp collisions was first computed in Ref. [11] in the purely collinear twist-3 approach. The complete result was obtained in Ref.…”

Section: The Computation Ofmentioning

confidence: 99%

“…Due to the lack of an additional hard scale, it is more appropriate to compute this observable using the collinear twist-3 approach [8][9][10][11][12] instead of TMD factorization. Phenomenologically, it was also studied in the generalized parton model [13,14].…”

mentioning

confidence: 99%

“…To resolve this sign mismatch problem, the authors of Ref. [17] suggested that a genuine twist-3 function ImÊ F [11](Ĥ ℑ FU in a different notation) instead of T F gives rise to the dominant contribution to A N . It is worthy to mention that the data on the SSA in SIDIS [18,19] doesn't disfavor this point of view because the Sivers function is not well constrained at large x in SIDIS, allowing flexible parametrizations of T F .…”

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confidence: 99%

“…[37] to work out the Wilson line structure in the fragmentation case is well justified. It is shown [37] that the contribution from the twist-3 fragmentation function related to the moment of the TMD Collins function [3,11] is strongly suppressed by saturation effect. In view of the recent measurement at RHIC [23], the genuine twist-3 fragmentation function turns out to be the only candidate for the main cause of A N .…”

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Single spin asymmetries in forward p−p/A collisions revisited: The role of color entanglement

Zhou

2017

Phys. Rev. D

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We calculate the single transverse spin asymmetries(SSA) for forward inclusive particle production in pp and pA collisions using a hybrid approach. It is shown that the Sivers type contribution to the SSA drops out due to color entanglement effect, whereas the fragmentation contribution to the spin asymmetry is not affected by color entanglement effect. This finding offers a natural solution for the sign mismatch problem.PACS numbers: Keywords:I. Introduction. -During the past three decades, the studies of transverse single spin asymmetries in high energy scatterings have greatly deepened our understanding of some central aspects of Quantum Chromodynamics(QCD) factorization theorem, among which the universality issue attracted a lot of attentions. Within transverse momentum dependent(TMD) factorization framework [1], a TMD distribution, known as the Sivers function f ⊥ 1T [2] was proposed to account for the observed large SSAs. It has been found that the Sivers function reverses sign between the semi-inclusive deeply inelastic scattering(SIDIS) and the Drell-Yan process [3][4][5]. The discovery of such novel and unique universality property has stimulated a lot of theoretical progress over the past decade. The preliminary results from the STAR collaboration and the COMPASS collaboration [6,7] seem to confirm the sign change. This is undoubtedly one of the most remarkable achievements in high energy spin physics.However, the situation with the SSA for the forward inclusive hadron production in pp collisions(denoted as A N ) p ↑ p → hX is more complicated. Due to the lack of an additional hard scale, it is more appropriate to compute this observable using the collinear twist-3 approach [8][9][10][11][12] instead of TMD factorization. Phenomenologically, it was also studied in the generalized parton model [13,14]. The twist-3 effects leading to the SSA can be factorized into various three-parton correlation functions. One of these is the Qiu-Sterman function T F [9] which can be related to the Sivers function [15],

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Single transverse-spin asymmetry for direct-photon and single-jet productions at RHIC

Kanazawa

Koike

2013

Physics Letters B

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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 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.

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The shear viscosity of a chemically equilibrating quark-gluon plasma at finite baryon density

Cited by 15 publications

References 33 publications

Transverse single spin asymmetries at smallxand the anomalous magnetic moment

Transverse single spin asymmetries at smallxand the anomalous magnetic moment

Single spin asymmetries in forward p−p/A collisions revisited: The role of color entanglement

Single transverse-spin asymmetry for direct-photon and single-jet productions at RHIC

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