Inclusive and diffractive dijet photoproduction in ultraperipheral heavy ion collisions at the LHC

TL;DR

This paper calculates inclusive and diffractive dijet photoproduction cross sections in ultraperipheral heavy ion collisions at the LHC, demonstrating their utility in constraining nuclear PDFs and exploring QCD factorization breaking.

Contribution

It provides next-to-leading order QCD calculations that fit ATLAS data and shows how this data refines nuclear parton distribution functions, also predicting diffractive processes.

Findings

Good agreement with ATLAS data for inclusive dijet photoproduction

Data reduces uncertainties in nuclear PDFs at small x by a factor of 2

Predictions for diffractive dijet photoproduction highlight potential to study QCD factorization breaking

Abstract

We calculate the cross section of inclusive dijet photoproduction in ultraperipheral collisions (UPCs) of heavy ions at the CERN Large Hadron Collider using next-to-leading order perturbative QCD and demonstrate that it provides a good description of the ATLAS data. We study the role of this data in constraining nuclear parton distribution functions (nPDFs) using the Bayesian reweighting technique and find that it can reduce current uncertainties of nPDFs at small $x$ by a factor of 2. We also make predictions for diffractive dijet photoproduction in UPCs and examine its potential to shed light on the disputed mechanism of QCD factorization breaking in diffraction.