NLO corrections to timelike, spacelike and double deeply virtual Compton scattering

TL;DR

This paper computes next-to-leading order QCD corrections to various Compton scattering processes, highlighting differences between timelike and spacelike cases, including new absorptive parts and pi^2 terms that impact theoretical predictions.

Contribution

It provides the first detailed calculation of NLO corrections for timelike, spacelike, and double deeply virtual Compton scattering, emphasizing the differences and new features arising in the timelike case.

Findings

Identified significant pi^2 contributions in timelike scattering amplitudes.

Analyzed the difference between timelike and spacelike coefficient functions.

Revealed the presence of absorptive parts in the amplitudes.

Abstract

We calculate the O(alpha_s) corrections to the timelike, spacelike and double deeply virtual Compton scattering amplitudes in the generalized Bjorken scaling region. Special attention is devoted to studies of the difference between the next to leading order timelike and spacelike coefficient functions, which plays for this process a role analogous to the large K factor which was much discussed in the analysis of inclusive Drell Yan cross sections. Also in the present studies the timelike nature of the hard scale gives rise to new absorptive part of the amplitude and to the presence of characteristic pi^2 terms, which can potentially lead to sizeable corrections.