The forward photon production and the gluonic content of the real and virtual photon at the HERA collider

TL;DR

This paper investigates prompt photon production at HERA, revealing significant gluonic contributions in real and virtual photons, and discusses the potential to extract their gluonic densities using observed enhancements.

Contribution

It provides new insights into gluonic content of photons at HERA and explores the BFKL approach for forward particle production analysis.

Findings

Large enhancement in photon production over the Born term, up to a factor of 35 for real photons.

Gluonic interactions dominate in forward photon production, enabling gluonic density extraction.

Discussion of BFKL approach applicability to forward particle production at HERA.

Abstract

The discussion on the production of prompt photons with pT of a few GeV in the tagged process ep -> e gamma X with small Q^2 (DIC process) at the HERA collider is presented. Photons produced in the forward (proton) direction are mainly originating from subprocesses involving interactions of the gluonic content of the exchanged photon. The large enhancement over the Born term (direct photon) is found up to a factor of 35 for a real photon and up to 5 for a virtual photon with a squared virtuality 1 GeV^2. It gives a possibility of extracting a gluonic density of the real and of the virtual photon. The BFKL approach to the description of the forward particle production is shortly discussed.