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

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 $QR\to \gamma q$ 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 $\sqrt{S}=24\mathrm{GeV}-13\mathrm{TeV}$. 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.

Comments: 27 pages, 12 figures, 1 Table