Inclusive J/Psi photoproduction and polarization at HERA in the kt-factorization approach

TL;DR

This paper studies inclusive J/Psi meson production and polarization at HERA using the kt-factorization QCD approach, incorporating various gluon densities and comparing predictions with experimental data.

Contribution

It introduces a comprehensive kt-factorization model for J/Psi photoproduction, including polarization analysis and both direct and resolved photon contributions.

Findings

Predictions agree with H1 and ZEUS data

Polarization parameters are sensitive to production dynamics

Both CCFM and KMR gluon densities are effective

Abstract

We investigate the inclusive photoproduction of J/Psi mesons at HERA within the framework of the kt-factorization QCD approach. Our consideration is based on the color singlet model supplemented with the relevant off-shell matrix elements and the CCFM and KMR unintegrated gluon densities in a proton and in a photon. Both the direct and resolved photon contributions are taken into account. Our predictions are compared with the recent experimental data taken by the H1 and ZEUS collaborations. Special attention is put on the J/Psi polarization parameters lambda and nu which are sensitive to the production dynamics.