Beyond the proton collinear factorization in heavy quark production in pA collisions at low x

TL;DR

This paper examines the limitations of proton collinear factorization in heavy quark production during high-energy pA collisions at low x, highlighting the breakdown of factorization when nucleus saturation effects are significant.

Contribution

It challenges the common assumption of valence quark factorization in heavy quark production, showing its validity only under specific saturation conditions.

Findings

Factorization breaks down at high nucleus saturation momentum.

Significant decrease in cross section at large total and small relative transverse momenta.

Valence quark interactions cannot be neglected in relevant phenomenological scenarios.

Abstract

We consider heavy quark production in high energy pA collisions and investigate the contribution of interactions of valence quarks of proton with the nucleus. The often made assumption that valence quarks of proton can be factored out is justified only if the nucleus saturation momentum is much smaller than the heavy quark mass. This is not the case in phenomenologically relevant situations. Breakdown of factorization manifests itself in substantial decrease of the cross section at large total and small relative transverse momenta of the heavy quark -antiquark pair.