Ultraperipheral collisions and low-x physics

TL;DR

Ultraperipheral collisions at high-energy colliders provide a unique environment to study gluon distributions at small x, with recent theoretical advances improving the understanding of exclusive processes at NLO accuracy and experimental results on vector meson production.

Contribution

The paper reviews recent theoretical developments in NLO QCD calculations for exclusive processes in ultraperipheral collisions and their relevance to small-x physics.

Findings

Advances in NLO QCD calculations for exclusive processes.

Experimental evidence from vector meson production.

Implications for small-x gluon structure studies.

Abstract

Ultraperipheral collisions at the LHC and RHIC offer the highest currently available energy for photon-nucleon and photon-nucleus collisions. Thus they are a valuable tool for studying the gluonic structure of hadrons and nuclei at small $x$. We discuss recent theoretical work towards understanding such exclusive processes at NLO accuracy in QCD perturbation theory. These theoretical advances are also immediately relevant for understanding the physics of deep inelastic scattering at small $x$. We also discuss experimental results in ultraperipheral collisions, most prominently for exclusive vector meson production.