Inclusive photon production and photon-jet correlations in hadronic collisions

TL;DR

This paper compares $k_t$-factorization and NLO collinear-factorization methods for photon-jet correlations in high-energy hadronic collisions, highlighting the dependence on gluon distributions and the dominance of NLO contributions in certain kinematic regions.

Contribution

It provides a detailed comparison of two theoretical approaches for photon-jet correlations, emphasizing the impact of different unintegrated gluon distributions and the dominance of NLO contributions.

Findings

NLO collinear contributions dominate at small azimuthal angles.

Results depend significantly on the choice of unintegrated gluon distributions.

Different approaches yield varying correlation patterns in photon-jet observables.

Abstract

We compare results of $k_t$-factorization approach and next-to-leading order collinear-factorization approach for photon-jet correlations in $pp$ and $p \bar p$ collisions at RHIC, Tevatron and LHC energies. We discuss correlations in azimuthal angle between photon and jet as well as correlations in two-dimensional space of photon and jet transverse momenta. Different unintegrated gluon/parton distributions are used in the $k_t$-factorization approach. The results depend on UGDF/UPDF used. The collinear NLO $2 \to 3$ contributions dominate over $k_t$-factorization cross section at small relative azimuthal angles as well as for asymmetric transverse momentum configurations.