Study on the low mass Drell-Yan production at the CERN LHC within the dipole formalism

Ducati, M. B. Gay; Griep, Mirian Thurow; Machado, M. V. T.

doi:10.1103/physrevd.89.034022

Cited by 12 publications

(6 citation statements)

References 25 publications

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“…On the other hand, for M DY < 10.5 GeV the extraction of the DY signal is extremely delicate, due to the large background of lepton pairs coming from heavy-flavor hadron decays (adding to those from quarkonia up to the Υ(3S) of mass 10.35 GeV) [31]. Note that this mass range has also been considered in saturation studies [32,33] although no DY nuclear modification factor was determined.…”

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confidence: 99%

Disentangling shadowing from coherent energy loss using the Drell-Yan process

Arleo

Peigné

2017

Phys. Rev. D

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We suggest the measurement of Drell-Yan (DY) lepton pairs in p-Pb collisions at the LHC ( √ s = 5.02 TeV) in order to disentangle the relative contributions of shadowing and coherent energy loss in quarkonium production off nuclei. The nuclear modification of low mass DY production is computed at NLO using various sets of nuclear parton densities. It is then observed that shadowing effects strongly cancel out in the J/ψ over DY suppression ratio R ψ pA (y) R DY pA (y), unlike the effect of coherent energy loss. Such a measurement could be performed at forward rapidity by the ALICE and LHCb collaborations at the LHC. PACS numbers: 24.85.+p, 14.40.Pq, Measurements of J/ψ production in p-Pb collisions at the LHC ( √ s = 5.02 TeV) by ALICE [1,2] and LHCb [3], and the observation of a strong attenuation at large rapidity with respect to the p-p data interpolation at the same collision energy, has triggered an intense debate on the origin of such a nuclear suppression [4]. Several groups have attributed the suppression to the depletion of the gluon distribution in the target nucleus expected at small x 2 10 −2 . Such a depletion, commonly named 'shadowing', is currently either incorporated in nuclear parton distribution functions (nPDFs) obtained from global fits based on DGLAP evolution, or determined from non-linear QCD evolution within the saturation formalism (see [5,6] for topical reviews). However another fundamental phenomenon, namely coherent parton energy loss in cold nuclear matter [7][8][9][10][11][12][13][14], could explain these data. It is therefore crucial to quantify the relative effects of shadowing and coherent energy loss. In this Letter, we show that the measurement of Drell-Yan (DY) lepton pairs of relatively low mass (10 M DY 20 GeV) in p-A collisions could be decisive to reach this goal. As a consequence, this measurement would shed light on the production of hadrons in p-A collisions, expected to be sensitive to coherent energy loss [7] on top of possible shadowing effects.Coherent energy loss and shadowing are two distinct effects, and should in principle be both taken into account in nuclear suppression models. However, as discussed in [8, 10] coherent energy loss alone allows one to describe J/ψ nuclear suppression observed at large x F at fixed-target collision energies, √ s 40 GeV [15], with a value of the cold nuclear matter transport coefficient q 0 = 0.07 − 0.09 GeV 2 /fm. This is consistent with the fact that shadowing is expected to be small at those energies. Taking in addition into account the shadowing given by either EPS09 [16] or DSSZ [17] next-to-leading order (NLO) nPDF sets these data can be described with a slightly smaller value ofq 0 , although energy loss re-mains the dominant effect at fixed-target energies [8]. Extrapolating coherent energy loss to collider energies leads to a central prediction [8] (with a rather narrow theoretical uncertainty band [4]) which agrees well with the J/ψ suppression data measured in d-Au collisions at RHIC [18,19] and p-Pb collisions at the ...

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confidence: 99%

Disentangling shadowing from coherent energy loss using the Drell-Yan process

Arleo

Peigné

2017

Phys. Rev. D

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“…The study of the Drell-Yan process in the color dipole approach has been the subject of many theoretical and phenomenological works, see for example Refs. [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. In this formalism, the physical picture is the following: a collinear quark emitted by the projectile proton can radiate a virtual photon either before or after interacting with the dense color field of the target.…”

Section: Formalismmentioning

confidence: 99%

“…Using similar notations as in Ref. [13], the dilepton pair production cross section can be written, in the limit of massless quarks, as…”

Section: Formalismmentioning

confidence: 99%

Nuclear modification of forward Drell-Yan production at the LHC

Ducloué¹

2017

Phys. Rev. D

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Forward Drell-Yan production at high energy can provide important constraints on gluon densities at small x, in the saturation regime. In this work, we focus on the nuclear modification of this process, which could be measured at the LHC in the near future. For this, we employ the color dipole approach, using the optical Glauber model to relate the dipole cross section of a nucleus to the one of a proton. Combining these results with our earlier results for forward J=ψ production, we compute the ratio of the nuclear modification factors of these two processes. This observable was recently suggested as a way to distinguish between initial and final state effects in forward particle production.

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“…refs. [29][30][31][32][33][34]. Later on also the momentum representation of the forward and general Drell-Yan process were elaborated in detail [35,36].…”

Section: Jhep01(2017)005mentioning

confidence: 99%

Twist decomposition of Drell-Yan structure functions: phenomenological implications

Brzeminski

Motyka

Sadzikowski

et al. 2017

J. High Energ. Phys.

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The forward Drell-Yan process in pp scattering at the LHC at √ S = 14 TeV is considered. We analyze the Drell-Yan structure functions assuming the dominance of a Compton-like emission of a virtual photon from a fast quark scattering off the small x gluons. The color dipole framework is applied to perform quantitatively the twist decomposition of all the Drell-Yan structure functions. Two models of the color dipole scattering are applied: the Golec-Biernat-Wüsthoff model and the dipole cross section obtained from the Balitsky-Fadin-Kuraev-Lipatov evolution equation. The two models have essentially different higher twist content and the gluon transverse momentum distribution and lead to different significant effects beyond the collinear leading twist description. It is found that the gluon transverse momentum effects are significant in the Drell-Yan structure functions for all Drell-Yan pair masses M , and the higher twist effects become important for M 10 GeV. It is found that the structure function W T T related to the A 2 angular coefficient and the Lam-Tung observable A 0 − A 2 are particularly sensitive to the gluon k T effects and to the higher twist effects. A procedure is suggested how to disentangle the higher twist effects from the gluon transverse momentum effects.

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Study on the low mass Drell-Yan production at the CERN LHC within the dipole formalism

Cited by 12 publications

References 25 publications

Disentangling shadowing from coherent energy loss using the Drell-Yan process

Disentangling shadowing from coherent energy loss using the Drell-Yan process

Nuclear modification of forward Drell-Yan production at the LHC

Twist decomposition of Drell-Yan structure functions: phenomenological implications

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