Deeply virtual electroproduction of photons and mesons on the nucleon : leading order amplitudes and power corrections

TL;DR

This paper estimates leading order amplitudes for exclusive photon and meson electroproduction at large Q^2, incorporating power corrections from parton transverse momentum and soft overlap contributions, relevant for upcoming experiments.

Contribution

It generalizes the skewed parton distribution formalism to include parton transverse momentum dependence and compares soft overlap contributions with leading order amplitudes.

Findings

Power corrections are significant at moderate Q^2 values.

Soft overlap contributions can be comparable to leading order amplitudes.

Estimates provided for experimental kinematics.

Abstract

We estimate the leading order amplitudes for exclusive photon and meson electroproduction reactions at large Q^2 in the valence region in terms of skewed quark distributions. As experimental investigations can currently only be envisaged at moderate values of Q^2, we estimate power corrections due to the intrinsic transverse momentum of the partons in the meson wavefunction and in the nucleon. To this aim the skewed parton distribution formalism is generalized so as to include the parton intrinsic transverse momentum dependence. Furthermore, for the meson electroproduction reactions, we calculate the soft overlap type contributions and compare with the leading order amplitudes. We give first estimates for these different power corrections in kinematics which are relevant for experiments in the near future.