Nuclear parton density modifications from low-mass lepton pair production at the LHC

Abstract

In this article, we investigate the potential of low-mass lepton pair production in proton-ion collisions at the LHC to constrain nuclear modifications of parton densities. Similarly to prompt photon production, the transverse momentum spectrum is shown to be dominated by the QCD Compton process, but has virtually no fragmentation or isolation uncertainties. Depending on the orientation of the proton and ion beams and on the use of central or forward detector components, all interesting regions of nuclear effects (shadowing, antishadowing, isospin and EMC effects) can be probed. Ratios of cross sections allow to eliminate theoretical scale and bare-proton parton density errors as well as many experimental systematic uncertainties.

A QCD analysis of LHCb D-meson data in p+Pb collisions

“…Good candidates at hadron colliders include e.g. low-mass Drell-Yan dilepton and isolated-photon production at low transverse momentum p T [29][30][31][32][33][34][35]. Isolated photons in p+Pb collisions have already been measured at central rapidities [36], and the large-y measurements appear to be within the capabilities of the LHCb collaboration [37].…”

Probing the small-x nuclear gluon distributions with isolated photons at forward rapidities in p+Pb collisions at the LHC

“…In the near future, the most promising source for new nPDF constraints are the hard processes in p+Pb collisions at the LHC [20][21][22][23][24][25][26][27][28]. With the naive leading order (LO) 2 → 2 kinematics one can estimate the nuclear-side x (that is, x 2 ) from…”

Impact of scale, nuclear PDF and temperature variations on the interpretation of medium-modified jet production data from the LHC

“…Fig. 25 Comparison of the EPPS16 nuclear modifications (black central curve with shaded uncertainty bands) with those from the nCTEC15 analysis [35] (red curves with hatching) at Q 2 = 10 GeV 2…”

“…In figure 1 we show for later reference a comparison of the nuclear PDF modifications at Q 2 = 10 GeV 2 for up/down valence and sea (including strange) quarks as well as gluons as parametrised in nCTEQ15 (red curves with hatching) [31] and EPPS16 (black central curve with shaded uncertainty bands) [32]. Note that nPDFs are continuously being updated to include in particular more LHC [35][36][37][38][39] and JLab data [40] and NNLO corrections [41,42].…”