Single isolated photon production in the NLO${}^\star$ approximation of the Parton Reggeization Approach

TL;DR

This paper investigates high-energy isolated photon production using the NLO* approximation of the Parton Reggeization Approach, incorporating new subtraction schemes and comparing results with experimental data across a wide energy spectrum.

Contribution

It introduces a subtraction scheme to avoid double counting in the Parton Reggeization Approach and demonstrates its self-consistency with experimental data.

Findings

Achieved satisfactory agreement with experimental data up to high transverse momentum ratios.

Validated the NLO* approximation of the Parton Reggeization Approach against collider data.

Provided predictions for future NICA experiment measurements.

Abstract

The hadroproduction of single isolated photon at high energies is studied within the framework of the NLO${}^\star$ approximation of the Parton Reggeization Approach based on the modified Multi-Regge limit of the hard scattering QCD amplitudes. The contribution from the LO subprocess $Q \bar Q \to \gamma$ and the NLO tree-level corrections $Q R \to \gamma q$ and $Q \bar Q \to \gamma g$ are considered. To avoid specific double counting in rapidity between tree-level corrections to the hard scattering coefficient and unintegrated PDFs, a corresponding subtraction scheme is proposed. We demonstrated self-consistency of the Parton Reggeization Approach using the subtraction scheme. The results of calculations are compared with data from various Collaborations in the wide energy range $\sqrt{S} = 24 \ {\rm GeV} - 13 \ {\rm TeV}$. We obtained a quite satisfactory agreement with data up to $p_T^\gamma / \sqrt{S} \simeq 0.2 - 0.3$. Predictions for the future SPD NICA experiment were discussed.