Exclusive photoproduction of lepton pairs at LHC

TL;DR

This paper discusses the measurement of exclusive dilepton photoproduction at the LHC, which can reveal insights into gluon distributions and nuclear effects through a process analogous to deeply virtual Compton scattering.

Contribution

It introduces the study of timelike Compton scattering in ultraperipheral collisions as a novel method to probe generalized parton distributions at high energies.

Findings

Potential to access gluon distributions in nucleons and nuclei

Feasibility of measuring nuclear effects in heavy ion collisions

Analog of deeply virtual Compton scattering at LHC energies

Abstract

Exclusive photoproduction of dileptons, gamma p ->l+ l- p, will be measured in ultraperipheral collisions at LHC. The mechanism where the lepton pair comes from a heavy timelike photon radiated from a quark interferes with the pure QED process gamma gamma ->l+ l- As an analog of deeply virtual Compton scattering, this timelike Compton scattering is a way to study generalized parton distributions in the nucleon or the nucleus. High energy kinematics will enable to focus on gluon distributions. Nuclear effects may be scrutinized in heavy ion collisions.