Gluon multiplicity in coherent diffraction of onium on a heavy nucleus

TL;DR

This paper derives a detailed formula for gluon production in high-energy onium-nucleus collisions, accounting for low-x evolution effects, with implications for collider experiments like RHIC, LHC, and EIC.

Contribution

It provides the first derivation of the diffractive gluon production cross section including low-x evolution effects in both onium size regimes.

Findings

Gluon multiplicity is small when onium size exceeds saturation scale in the quasi-classical case.

Low-x evolution significantly increases gluon multiplicity for large onium sizes.

Results have direct implications for experimental observations at RHIC, LHC, and EIC.

Abstract

We derive the cross section for the diffractive gluon production in high energy onium-nucleus collisions that includes the low-x evolution effects in the rapidity interval between the onium and the produced gluon and in the rapidity interval between the gluon and the target nucleus. We analyze our result in two limiting cases: when the onium size is much smaller than the saturation scale and when its size is much larger than the saturation scale. In the later case the gluon multiplicity is very small in the quasi-classical case and increases when the low-x evolution effects in onium become significant. We discuss the implications of our result for the RHIC, LHC and EIC phenomenology.