Kinematic power corrections for nucleon timelike Compton scattering

Determine the kinematic power corrections to nucleon timelike Compton scattering beyond leading power, including the corrections through twist four that have been obtained only for spin-zero targets.

Background

Timelike Compton scattering is the crossed process in which a real photon produces a timelike virtual photon that decays into a lepton pair. While leading-power factorization is established and leading-order kinematic power corrections have been calculated through twist four for a spin-zero target, the corresponding corrections for a nucleon target had not yet been derived in the review.