Parton model versus color dipole formulation of the Drell-Yan process

Raufeisen, J.; Peng, J. C.; Nayak, Gouranga C.

doi:10.1103/physrevd.66.034024

Cited by 52 publications

(72 citation statements)

References 45 publications

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“…The color dipole cross section arises as interference of the diagram in which the quark first interacts with the target with the diagram in which the quark first fluctuates in the quark-photon state. This result was first stated in [7] and derived in detail in [4].…”

Section: Using Eks and Nds Parameterizationsmentioning

confidence: 56%

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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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Section: Using Eks and Nds Parameterizationsmentioning

confidence: 56%

“…In this case, the color dipole approach is phenomenologically valid for small x 1 [4] -very backward rapidities. The cross section is written as:…”

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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“…It can thus be determined phenomenologically, for example, from the Deep Inelastic Scattering (DIS) data [5]. The dipole approach is formulated in the target rest frame where the DY process can be viewed as a bremsstrahlung of a virtual γ * /Z 0 boson off a projectile quark line [6,7]. In the high-energy limit, the projectile quark looses a small fraction of its momentum and can further fragment into a forward leading hadron, e.g.…”

Section: The European Physical Society Conference On High Energy Physmentioning

confidence: 99%

Study of J/Psi and Y production in association with leading hadron at RHIC and LHC energies

Basso¹,

Gonçalves²,

Nemchik³

et al. 2016

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2015)

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We demonstrate that current experimental data on γ/Z 0 and heavy quarkonium production in pp collisions at RHIC and LHC energies can be described by the color dipole formalism. Three different phenomenological models based on saturation physics are used to estimate the DrellYan (DY) dilepton spectra in such processes. In order to further constrain QCD dynamics we suggest to measure the azimuthal correlation function C(∆φ ) between mid-rapidity DY pairs and central/forward pions. On the other hand, this is a key background for C-odd heavy quarkonia (e.g. J/ψ and ϒ) production at high p T 's which can be accompanied by a high-p T hadron from fragmentation of an additional gluon according to the Color-Singlet model (CSM). As a first step, we have estimated the transverse momentum distributions J/ψ and ϒ in the dipole CSM and found a reasonable agreement with data at various energies. Similarly to the DY case we suggest to study correlations between a high-p T jet and J/ψ or ϒ in the dilepton channel at mid-rapidities.

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“…Although diagrammatically no dipole is present in bremsstrahlung, the dipole cross section arises when one takes the complex conjugate of the amplitude (photon emited before or after the interaction with the target), see Ref. [14] for a detailed derivation.…”

Section: Dilepton In the Dipole Approachmentioning

confidence: 99%

“…[14], where the old saturation model of Ref. [20] was used, the dipole approach was extrapolated to larger x 2 by introducing a threshold factor into the saturation scale, i.e.…”

Section: A the Dipole Cross Sectionmentioning

confidence: 99%

High density QCD through eletromagnetic probes

Betemps

2007

Braz. J. Phys.

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In this work we investigate the high density QCD system through the dilepton production. First, the dilepton production in the color dipole approach is investigated, studing perturbative unitarity corrections to the dipole cross section and its consequence in the transverse momentum distribution of the dileptons at RHIC and LHC energies. Second, the dilepton production in the context of the Color Glass Condensate is investigated. The transverse momentum distribution and the rapidity distribution are investigated to dilepton production at RHIC and LHC energies in this framework.

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Parton model versus color dipole formulation of the Drell-Yan process

Cited by 52 publications

References 45 publications

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

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

Study of J/Psi and Y production in association with leading hadron at RHIC and LHC energies

High density QCD through eletromagnetic probes

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