High Energy exclusive Leptoproduction of the rho-meson: Theory and Phenomenology

TL;DR

This paper models the high-energy exclusive leptoproduction of transversally polarized rho-mesons, incorporating twist 3 accuracy and saturation effects, and compares the results with HERA experimental data.

Contribution

It introduces a model for rho-meson leptoproduction at twist 3, including saturation effects, and validates it against HERA data for helicity amplitude ratios.

Findings

Model accurately describes HERA data on helicity ratios

Inclusion of saturation effects improves the model

Extension of dipole representation to twist 3

Abstract

We describe the hard leptoproduction of transversally polarized rho-meson, up to twist 3 accuracy, including 2- and 3- particles Fock-states, in the HERA kinematics of high center-of-mass energy. We first build a model based on a simple approach to the unintegrated gluon density (the parton impact factor) that we compare with H1 and ZEUS data for the ratios of helicity amplitudes T(gamma*T -> rhoT)/T(gamma*L -> rhoL) and T(gamma*T -> rhoL)/T(gamma*L -> rhoL) and get a good description of the data. We also show how saturation effects can be included in this model by extending the dipole representation of the scattering amplitude in coordinate space up to twist 3.