Reconsideration of the inclusive prompt photon production at LHC with kt-factorization

Abstract

We reconsider the inclusive production of isolated prompt photons in $pp$ collisions at the LHC energies in the framework of $k_T$-factorization approach. Our analysis is based on the $\mathcal{O}(\alpha {\alpha }_s)$ off-shell (depending on the transverse momenta of initial quarks and gluons) production amplitudes of $q^{\ast }{g}^{\ast }\to \gamma q$ and $q^{\ast }{\bar{q}}^{\ast }\to \gamma g$ partonic subprocesses and transverse momentum dependent (or unintegrated) quark and gluon densities in a proton, which are chosen in accordance with the Kimber-Martin-Ryskin prescription. We show that the sub-leading high-order $\mathcal{O}(\alpha {\alpha }_s^2)$ contributions, not covered by the non-collinear evolution of parton densities, are important to describe latest LHC data.

Comments: 13 pages, 7 figures