Probing gluon and heavy-quark nuclear PDFs with photon + heavy quark production in pA collisions

TL;DR

This paper investigates how photon plus heavy-quark jet production in proton-nucleus collisions can constrain nuclear gluon and heavy-quark PDFs, especially across different x regions at RHIC and LHC energies.

Contribution

It provides a detailed NLO QCD phenomenological analysis demonstrating the sensitivity of bb+Q production to nuclear PDFs and highlights its potential to improve their constraints.

Findings

Photon + heavy-quark production is highly sensitive to gluon and heavy-quark PDFs.

The nuclear production ratio R^{bb+Q}_{pA} can constrain nuclear PDFs over a broad x-range.

Complementary kinematic coverage at RHIC and LHC enhances PDF constraint capabilities.

Abstract

We present a detailed phenomenological study of direct photon production in association with a heavy-quark jet in pA collisions at the Relativistic Heavy Ion Collider (RHIC) and at the Large Hadron Collider (LHC) at next-to-leading order in QCD. The dominant contribution to the cross-section comes from the gluon--heavy-quark (gQ) initiated subprocess, making \gamma + Q production a process very sensitive to both the gluon and the heavy-quark parton distribution functions (PDFs). Additionally, the RHIC and LHC experiments are probing complementary kinematic regions in the momentum fraction x_2 carried by the target partons. Thus, the nuclear production ratio R^{\gamma+Q}_{pA} can provide strong constraints, over a broad x-range, on the poorly determined nuclear parton distribution functions which are extremely important for the interpretation of results in heavy-ion collisions.