Forward rapidity isolated photon production in proton-nucleus collisions

B. Ducloué (1) , T. Lappi , H. Mäntysaari

1 IPHT - Institut de Physique Théorique - UMR CNRS 3681

We calculate isolated photon production at forward rapidities in proton-nucleus collisions in the Color Glass Condensate framework. Our calculation uses dipole cross sections solved from the running coupling Balitsky-Kovchegov equation with an initial condition fit to deep inelastic scattering data and extended to nuclei with an optical Glauber procedure that introduces no additional parameters beyond the basic nuclear geometry. We present predictions for future forward RHIC and LHC measurements. The predictions are also compared to updated results for the nuclear modification factors for pion production, Drell-Yan dileptons and J / ψ mesons in the same forward kinematics, consistently calculated in the same theoretical framework. We find that leading order, running coupling high energy evolution in the CGC picture leads to a significant nuclear suppression at forward rapidities. This nuclear suppression is stronger for photons than for pions. We also discuss how this might change with next-to-leading order high energy evolution.

Mots clés: photon: production; energy: high; coupling constant: energy dependence; pi: production; cross section: dipole; higher-order: 0; higher-order: 1; nucleus; rapidity; color glass condensate; suppression; p nucleus; Balitsky-Kovchegov equation; deep inelastic scattering; Brookhaven RHIC Coll; boundary condition; Drell-Yan process; CERN LHC Coll; kinematics; dilepton; geometry; Glauber; optical; meson

Domaines: Physique des Hautes Energies - Phénoménologie [hep-ph]; Physique Nucléaire Théorique [nucl-th]

B. Ducloué, T. Lappi, H. Mäntysaari. Forward rapidity isolated photon production in proton-nucleus collisions. 27th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions, May 2018, Venice, Italy. pp.267-270, ⟨10.1016/j.nuclphysa.2018.10.064⟩. ⟨hal-02058263⟩