DbarD and DD pair production at the LHCb in the parton Reggeization approach

We study the inclusive DbarD and DD pair production in proton-proton collisions at the LHC at lead- ing order of the parton Reggeization approach endowed with universal scale-depended fragmen- tation functions for c-quark to D-meson and for gluon to D-meson transitions. We have described DbarD and DD distributions in azimuthal angle, as well as transverse momentum, rapidity distance, and invariant mass measured in the region of large rapidity 2 < y < 4 by the LHCb Collabora- tion at the LHC without free parameters. We have used Reggeized amplitudes for the processes RR - gg and RR - c barc which are obtained accordingly to Feynman rules of the L.N. Lipatov effective theory of Reggeized partons, and Kimber-Martin-Ryskin model for unintegrated gluon distribution function in a proton with Martin-Stirling-Thorne-Watt collinear parton distributions as inputs.