Prompt photon production in proton collisions as a probe of parton scattering in high energy limit

TL;DR

This paper investigates prompt photon production at the LHC using the $k_T$-factorization approach with different gluon distributions, comparing predictions to data to understand gluon dynamics in high energy proton collisions.

Contribution

It compares three unintegrated gluon distribution schemes within the $k_T$-factorization framework to analyze prompt photon production and differentiate their effectiveness using LHC data.

Findings

Sensitivity of photon transverse momentum distribution to gluon transverse momentum.

Differences between the three gluon distribution schemes in predicting data.

Assessment of the relevance of partonic channels in high energy limit.

Abstract

We study the prompt photon hadroproduction at the LHC with the $k_T$-factorization approach and the $qg^* \to q\gamma$ and $g^*g^* \to q\bar q\gamma$ partonic channels, using three unintegrated gluon distributions which depend on gluon transverse momentum. They represent three different theoretical schemes which are usually considered in the $k_T$-factorization approach, known under the acronyms: KMR, CCFM and GBW gluon distributions. We find sensitivity of the calculated prompt photon transverse momentum distribution to the gluon transverse momentum distribution. The predictions obtained with the three approaches are compared to data, that allows to differentiate between them. We also discuss the significance of the two partonic channels, confronted with the expectations which are based on the applicability of the $k_T$-factorization scheme in the high energy approximation.