Scale evolution of nuclear parton distributions

Eskola, Kari J.; Kolhinen, V.J.; Ruuskanen, P. V.

doi:10.1016/s0550-3213(98)00589-6

Cited by 307 publications

(596 citation statements)

References 58 publications

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“…other hand, reduction of the d-side yield may arise from the energy degradation of the d-side quarks due to multiple scattering in the Au nucleus. Gluon anti-shadowing [10] and the EMC effect [11] would enhance the d-side yield relative to the Au-side. The away-side correlation shapes in Au+Au collisions are broadened with respect to p+p as shown in Fig.…”

Section: Analysis Detailsmentioning

confidence: 99%

Jet-like correlations between forward- and mid- rapidity in p+p, d+Au and Au+Au collisions from STAR at

Molnár¹,

Collaboration²

2007

J. Phys. G: Nucl. Part. Phys.

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Abstract. In this proceedings we present STAR measurements of two particle azimuthal correlations between trigger particles at mid-rapidity (|η| < 1) and associated particles at forward rapidities (2.7 < |η| < 3.9) in p+p, d+Au and Au+Au collisions at √ s N N = 200 GeV. Two particle azimuthal correlations between a midrapidity trigger particle and forward-rapidity associated particles preferably probe large-x quarks scattered off small-x gluons in RHIC collisions. Comparison of the separate d-and Au-side measurements in d+Au collisions may potentially probe gluon saturation and the presence of Color Glass Condensate. In Au+Au collisions quark energy loss can be probed at large rapidities, which may be different from gluon energy loss measured at mid-rapidity.

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Section: Analysis Detailsmentioning

confidence: 99%

Jet-like correlations between forward- and mid- rapidity in p+p, d+Au and Au+Au collisions from STAR at

Molnár¹,

Collaboration²

2007

J. Phys. G: Nucl. Part. Phys.

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“…Going beyond leading order in Q 2 s /k 2 ⊥ appears to be tremendously complicated and we will not address this problem here. Instead we are going to construct a model of correlated two-particle production employing quasi-classical gluon distributions from [5,38] in the production formula inspired by collinear factorization [40,41], similar to how it was done in [12,13] in describing the multiplicity data at RHIC. We would also assume that in any given event either y 1 ≫ y 2 or y 1 ≪ y 2 .…”

Section: Calculation Of Vmentioning

confidence: 99%

“…3. To construct a model of minijet production which incorporates both hard and soft physics we have used k T factorized expression for two-jet production with the unintegrated gluon distributions given by the quasi-classical Glauber-Mueller expression [37,38,39,40,41,5]. These gluon distributions are characterized by the saturation scale Q s ≫ Λ QCD which insures applicability of small coupling approaches down to rather small transverse momenta of the produced particles.…”

Section: Introductionmentioning

confidence: 99%

Elliptic flow from minijet production in heavy ion collisions

Kovchegov¹,

Tuchin²

2002

Nuclear Physics A

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We calculate the contribution to the elliptic flow observable v 2 from two-particle correlations in minijet production in ultrarelativistic heavy ion collisions. We use a minijet production cross section derived in a model inspired by saturation approach to high energy scattering. Resulting differential elliptic flow v 2 (p T ) is an increasing function of p T for transverse momenta below the saturation scale Q s . At higher transverse momenta (p T > Q s ) differential flow stops growing and becomes approximately constant, reproducing the elliptic flow saturation data reported by STAR. The centrality dependence of the minijet contribution to v 2 is also in good agreement with the data.

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“…We use GRV98 [9,10] as the parton distribution function (PDF) of free protons. Two parameterizations of the nuclear PDFs are used: EKS [11][12][13] and nDS [14]. EKS parameterization gives the nPDF as the free proton PDF multiplied by a factor:…”

Section: Using Eks and Nds Parameterizationsmentioning

confidence: 99%

Confronting color dipole and intrinsic kT approaches in D-Y dilepton production

Betemps

Oliveira

2008

Braz. J. Phys.

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We study the Drell-Yan dilepton production in proton-nucleus collisions at RHIC energies. We use two different approaches: the usual intrinsic transverse momentum approach at NLO in the infinitum momentum frame; and the color dipole in the target rest frame. We compare both formalisms at backward rapidities (proton as a target). At forward rapidities, we use earlier results considering the nucleus in a Color Glass Condensate phase. We show qualitative agreement between the two formalisms through the nuclear modification ratio as a function of both rapidity and transverse momentum and that low-mass dileptons are relevant observables to probe nuclear effects.Keywords: Drell-Yan process; Dilepton production; Nuclear effects; Dipole frame; Infinite momentum frameIn a recent work[1], Drell-Yan dilepton production at backward rapidities in hadrons collisions was studied in the rest frame of the target, i. e., in the color dipole approach. In this work, we compare these previous results with results obtained used well know intrinsic k T approach in the infinitum momentum frame [2,3]. In this frame, the process is understood as the combination of two partons to create a virtual boson that subsequently splits in the dilepton. For dilepton mass M much smaller than the Z mass, the dominant process includes only the photon as the virtual boson. The dilepton production is of particular interest since dileptons do not interact strongly and therefore carry information about initial state effects.The kinematics used here are described now. Partons and hadrons are taken as massless, the momenta of hadrons A and B are P A and P B , and the momenta of partons are p A = x A P A and p B = x B P B (for now, partons are collinear to hadrons). The virtual photon momentum is q and q 2 = M 2 is the squared dilepton mass. The Mandelstam variables are given by: s = 2P A · P B , t = (q − P A ) 2 , and u = (q − P B ) 2 . We also define x 1 = 2P B · q/s, x 2 = 2P A · q/s, and the photon rapidity y = 1 2 ln(x 1 /x 2 ). It can be showed that:in which p T is the photon (also dilepton) transverse momentum. In IMF collinear approximation, partons are considered collinear to hadrons, without intrinsic transverse momentum. Using this framework at leading order, experimental results of transverse momentum distribution cannot be reproduced: although valid for large p T , collinear NLO p T distribution diverges at p T = 0 and is not in agreement with experiments for small p T . We consider then partonic intrinsic transverse momentum, i. e., partons are not collinear to hadrons [2,3]. The partonic distributions are change as the following prescription:In this paper, we consider h( k T ) = 1 2πb 2 exp k 2 T 2b 2 . Therefore, the cross section is given by [4,5]:In the above expression, it is included the NLO collinear double differential cross section:Using the modified minimal subtraction scheme (MS), D q (z) and D g (z) are given e.g. in Ref.[6] (C F = 4/3, T R = 1/2). The second term in the right hand side of equation 3 is calculated only from annihila...

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Scale evolution of nuclear parton distributions

Cited by 307 publications

References 58 publications

Jet-like correlations between forward- and mid- rapidity in p+p, d+Au and Au+Au collisions from STAR at

Jet-like correlations between forward- and mid- rapidity in p+p, d+Au and Au+Au collisions from STAR at

Elliptic flow from minijet production in heavy ion collisions

Confronting color dipole and intrinsic kT approaches in D-Y dilepton production

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