Twist-3 contribution to deeply virtual electroproduction of pions

TL;DR

This paper investigates the impact of twist-3 contributions on deeply virtual pion production, demonstrating improved theoretical descriptions aligned with experimental data by including higher-twist effects and novel regularization methods.

Contribution

It introduces a detailed calculation of twist-3 effects in DVMP, incorporating both 2-body and 3-body meson components, and proposes two regularization techniques for end-point singularities.

Findings

Good agreement of cross sections with experimental data

Inclusion of twist-3 contributions improves theoretical models

Regularization methods effectively handle end-point singularities

Abstract

We discuss deeply virtual meson production (DVMP), focusing on the role of higher-twist contributions in the description of deeply virtual pseudoscalar mesons at experimentally accessible energies. The standard collinear approach at the lowest twist does not adequately describe deeply virtual $\pi_0$ production. By incorporating twist-2 transversity generalized parton distributions (GPDs) and a twist-3 meson distribution amplitude, we have determined the twist-3 contribution, which includes both the 2-body ($q\bar{q}$) and 3-body ($q\bar{q}g$) meson Fock components. Two methods to regularize the end-point singularities are introduced - quark transverse momenta and a gluon mass. The resulting cross sections show good agreement with experimental data, paving the way for a more comprehensive confrontation of theory and experiment at leading order and beyond.