Exclusive photoproduction of lepton pairs at LHC

Understand

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.