Timelike vs spacelike DVCS from JLab, Compass to ultraperipheral collisions and AFTER@LHC

TL;DR

This paper discusses how timelike and spacelike virtual Compton scattering serve as complementary methods to explore generalized parton distributions, emphasizing the significance of gluonic contributions across various experimental settings.

Contribution

It highlights the importance of gluonic contributions in both timelike and spacelike DVCS, and explores their study across multiple experimental platforms from JLab to LHC.

Findings

Gluonic contributions are significant even at medium energies.

Ultraperipheral collisions can probe generalized parton distributions.

Timelike and spacelike DVCS are complementary tools.

Abstract

Timelike and spacelike virtual Compton scattering in the generalized Bjorken scaling regime are complementary tools to access generalized parton distributions. We stress that the gluonic contributions are by no means negligible, even in the medium energy range which will be studied intensely at JLab12 and in the COMPASS-II experiment at CERN. Ultraperipheral collisions with proton or ion beams may also be used at RHIC and at collider or fixed target experiments at LHC.