Abstract
We explore the possibility of measuring nuclear gluon distributions at the Relativistic Heavy-Ion Collider (RHIC) with $\sqrt{s}=200 \, {\rm GeV}$ proton-nucleus collisions. In addition to measurements at central rapidity, we consider also observables at forward rapidity, consistent with proposed upgrades to the experimental capabilities of STAR and sPHENIX. The processes we consider consist of Drell-Yan dilepton, dijet, and direct photon-jet production. The Drell-Yan process is found to be an efficient probe of gluons at small momentum fractions. In order to fully utilize the potential of Drell-Yan measurements we demonstrate how the overall normalization uncertainty present in the experimental data can be fixed using other experimental observables. An asset of the RHIC collider is its flexibility to run with different ion beams, and we outline how this ability could be taken advantage of to measure the $A$ dependence of gluon distributions for which the current constraints are scarce.
Highlights
Good control over the partonic structure of protons and heavier nuclei has become an indispensable ingredient in modern particle, heavy-ion, and astroparticle physics
We report our studies on the future prospects for constraining nuclear parton distribution functions (PDFs) at Relativistic Heavy-Ion Collider (RHIC), with measurements at central and forward rapidities where forward acceptance corresponds to that proposed for the STAR [19] and sPHENIX experiments [20]
Using the Au nucleus as a test case, we have examined the prospects for constraining nuclear gluon PDFs at RHIC with new measurements that assume detector acceptances similar to those proposed for STAR and sPHENIX with forward upgrades
Summary
Good control over the partonic structure of protons and heavier nuclei has become an indispensable ingredient in modern particle, heavy-ion, and astroparticle physics. Pffiffi center-of-mass (c.m.) energies of RHIC, s 1⁄4 200 and 500 GeV, is that the underlying event is not as large as it is at the LHC, and e.g., jets can be better resolved at lower transverse momenta (pT) [8,9]. These jet measurements are compatible with next-to-leading-order (NLO) perturbative QCD calculations [9,10,11] down to pT ∼ 10 GeV (which is the minimum pT of the measurements), so nothing really forbids using them in PDF analysis. We will base our study mainly on the EPPS16 analysis
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