Prompt-photon plus jet photoproduction with ZEUS at DESY HERA in the parton Reggeization approach

TL;DR

This paper investigates prompt photon plus jet photoproduction at ZEUS using the parton Reggeization approach, improving theoretical accuracy and comparing predictions with recent experimental data.

Contribution

It introduces the Reggeized-quark formalism and exact gauge-invariant amplitudes for off-shell initial-state quarks and gluons in the k_T-factorization framework.

Findings

Good agreement with ZEUS data for direct-dominating processes

Highlights importance of nonfactorizable higher-order corrections

Discusses differences from previous k_T-factorization calculations

Abstract

We study the photoproduction of isolated prompt photons associated with hadron jets in the framework of the parton Reggeization approach. The main improvements with respect to previous studies in the k_T-factorization framework include the application of the Reggeized-quark formalism, the generation of exactly gauge-invariant amplitudes with off-shell initial-state quarks, and the exact treatment of the gamma+R -> gamma+g box contribution with off-shell initial-state gluons. In this proceedings, the new data set, published recently by ZEUS collaboration is analyzed, were the distributions in photon and jet rapidity, transverse energy, azimuthal angle between photon and jet and proton momentum fraction are presented for different values of measured photon momentum fraction x_gamma <0.7, 0.8 and x_gamma>0.8$. The good agreement of measured distributions with our predictions is observed for the direct-dominating part of the data set. The comparison with the previous calculations in k_T-factorization, role of nonfactorizable higher-order and hadronization corrections is discussed.