On timelike and spacelike hard exclusive reactions

TL;DR

This paper establishes next-to-leading order relations between spacelike and timelike exclusive hadronic processes in QCD, enabling new tests of leading twist analyses through simple amplitude relations.

Contribution

It derives space-to-timelike amplitude relations at NLO accuracy, connecting different exclusive processes in QCD for the first time.

Findings

Derived NLO space-to-timelike amplitude relations

Provided a new test for leading twist analyses

Linked electroproduction and meson production processes

Abstract

We show to next-to-leading order accuracy in the strong coupling alpha_s how the collinear factorization properties of QCD in the generalized Bjorken regime relate exclusive amplitudes for spacelike and timelike hadronic processes. This yields simple space--to--timelike relations linking the amplitudes for electroproduction of a photon or meson to those for photo- or meso-production of a lepton pair. These relations constitute a new test of the relevance of leading twist analyzes of experimental data.