Angular decorrelations in $\gamma + 2 jet$ events at high energies in the parton Reggeization approach

Abstract

We study associated production of prompt photon and two jets at high energies in the framework of the parton Reggeization approach, which is based on multi-Regge factorization of hard processes and Lipatov's effective theory of Reggeized gluons and quarks. In this approach, initial-state off-shell effects and transverse momenta of initial partons are included in a gauge-invariant way. We compute azimuthal angle difference spectra in $\gamma + 2 jets$ events and compare results with data from D0 Collaboration at the Tevatron. It was found that agreement between predictions and data can be achieved only under assumption on strong violation in transverse momentum ordering during initial-state QCD evolution which corresponds multi-Regge kinematical regime instead of DGLAP picture.