The scale dependent nuclear effects in parton distributions for practical applications

Eskola, Kari J.; Kolhinen, V.J.; Salgado, Carlos A.

doi:10.1007/s100520050513

Cited by 489 publications

(872 citation statements)

References 17 publications

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“…which we take here from the earlier global analysis, EPS09 [3] or EKS98 [4]. As this constrains only the spatially averaged modification, we need to make an assumption about the spatial dependence.…”

Section: Frameworkmentioning

confidence: 99%

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EPS09s and EKS98s: Impact parameter dependent nPDF sets

et al. 2013

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In our recent study we have determined two new spatially dependent nuclear PDF (nPDF) sets, EPS09s and EKS98s. With these, the hard-process cross-sections can be calculated in different centrality classes consistently with the globally analyzed nPDFs for the first time. The sets were determined by exploiting the A-systematics of the globally fitted nPDF sets, EPS09 and EKS98. For the spatial dependence of the nPDFs we used a power series ansatz in the nuclear thickness function T A . In this flash talk we introduce the framework, and present our NLO EPS09s-based predictions for the nuclear modification factor in four centrality classes for inclusive neutral pion production in p+Pb collisions at the LHC and for inclusive prompt photon production in d+Au collisions at RHIC at midrapidity.

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Section: Frameworkmentioning

confidence: 99%

“…in Refs. [3,4]. So far all the global fits have considered only minimum bias observables and thus the resulting nPDFs should be considered as spatially averaged quantities.…”

Section: Introductionmentioning

confidence: 99%

EPS09s and EKS98s: Impact parameter dependent nPDF sets

et al. 2013

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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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“…We use CTEQ4L parton distribution functions (PDFs) and we include, for Pb-Pb, their nuclear modification (shadowing) in the EKS98 parameterization [15]. For the hadronization to D mesons, we use a fragmentation function parameterized from PYTHIA pp simulations done with the standard Lund string model.…”

Section: Estimate Of D-meson Suppression At the Lhcmentioning

confidence: 99%