Production of isolated photons with large transverse momenta at LHC in the regge limit of QCD

The article discusses the production of prompt isolated photons with large transverse momenta at the LHC at energies $\sqrt{s} = 8$ and $13$ TeV in the parton Reggeization approach, which is based on the factorization theorem for hard processes at high energies and the effective theory of Reggeized gluons and quarks by L.N. Lipatov. Unintegrated parton distributions in the parton Reggeization approach were obtained in the modified Kimber–Martin–Ryskin model proposed earlier by the authors of the article. In numerical calculations, only the contribution of the main parton process, $R + Q (\bar Q) \to \gamma +q(\bar q) $, is taken into account, since the contribution of other processes does not exceed $5$–$10 \%$. The calculation results are compared with the predictions obtained in the collinear parton model. Good agreement of calculations in the parton Reggeization approach with experimental data obtained by the ATLAS collaboration is shown.