On the description of exclusive processes beyond the leading twist approximation

TL;DR

This paper develops a framework for describing hard exclusive processes beyond the leading twist approximation using a Taylor expansion approach, simplifying the set of non-perturbative correlators needed.

Contribution

It introduces a minimal set of non-perturbative correlators for higher-twist descriptions, demonstrating equivalence of coordinate and momentum space methods at twist 3.

Findings

Framework based on Taylor expansion around light-cone directions

Minimal set of non-perturbative correlators after applying QCD equations of motion

Equivalence of coordinate and momentum space descriptions at twist 3

Abstract

We describe hard exclusive processes beyond the leading twist approximation in a framework based on the Taylor expansion of the amplitude around the dominant light-cone directions. This naturally introduces an appropriate set of non-perturbative correlators whose number is minimalized after taking into account QCD equations of motion and the invariance under rotation on the light-cone. We examplify this method at the twist 3 level and show that the coordinate and momentum space descriptions are fully equivalent.