Refined TMD Gluon Density in a Proton from the HERA and LHC Data

We update the phenomenological parameters of the Transverse Momentum Dependent (TMD, or unintegrated) gluon density in a proton proposed in our previous studies. This analysis is based on the analytical expression for starting gluon distribution which provides a self-consistent simultaneous description of HERA data on proton structure function F₂(x, Q²), reduced cross section for the electron-proton deep inelastic scattering at low Q² and soft hadron production in pp collisions at the LHC conditions. We extend it to the whole kinematical region using the Catani–Ciafaloni–Fiorani–Marchesini (CCFM) evolution equation. Exploiting our previous results on a number of semihard QCD processes, we performed a combined fit to an extended set of LHC and HERA data, comprising a total of 509 points from 16 data sets. We illustrate our fit by applying the derived TMD gluon density in a proton to inclusive prompt photon photoproduction at HERA.