Cross sections for hard exclusive electroproduction of pi+ mesons on a hydrogen target

TL;DR

This study measures the cross sections for exclusive pi+ meson electroproduction on hydrogen, comparing experimental data with theoretical models based on Generalized Parton Distributions and Regge formalism.

Contribution

It provides detailed measurements of the virtual-photon cross sections and evaluates the applicability of GPD and Regge models to describe the data.

Findings

GPD model agrees at low |t| with power corrections

Regge model accurately describes magnitude and dependencies

Data supports the validity of theoretical approaches in certain kinematic regions

Abstract

The exclusive electroproduction of pi+ mesons was studied with the Hermes spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off an internal hydrogen gas target. The virtual-photon cross sections were measured as a function of the Mandelstam variable t and the squared four momentum -Q^2 of the exchanged virtual photon. A model calculation based on Generalized Parton Distributions is in fair agreement with the data at low values of |t| if power corrections are included. A model calculation based on the Regge formalism gives a good description of the magnitude and the t and Q^2 dependences of the cross section.