Theory and phenomenology of helicity amplitudes for high energy exclusive leptoproduction of the rho-meson

TL;DR

This paper reviews two theoretical approaches to describe high-energy exclusive leptoproduction of transversally polarized rho-mesons, comparing predictions with experimental data and exploring impact factor transformations and saturation effects.

Contribution

It introduces two novel methods for modeling rho-meson leptoproduction, including impact factor calculations up to twist 3 and impact parameter space transformation.

Findings

Predictions align with H1 and ZEUS data for helicity amplitude ratios.

Impact factor transformation supports the dipole picture.

Discussion of nucleon saturation effects implementation.

Abstract

We review here two approaches to describe hard leptoproduction of transversally polarized rho-meson, based on recent calculation of the gamma*T -> rhoT impact factor up to twist 3 accuracy in the collinear factorization frame, including 2- and 3- particles Fock-states. The first approach uses a model of the unintegrated gluon density (the proton impact factor) which allows a comparison of our predictions 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). In the second approach, we transform the gamma*T -> rhoT impact factor into the impact parameter space. We show that the transformed amplitude factorizes according to conventional dipole picture. We shortly discuss a way to implement the nucleon saturation effects in our approach.