LHC soft physics and transverse momentum dependent gluon density at lowx

Abstract

We study the unintegrated, or transverse momentum dependent gluon distribution obtained from the best description of the LHC data on the inclusive spectra of hadrons produced in the midrapidity region and at low transverse momenta at the starting scale ${Q}_{0}^{2}=1\text{ }\text{ }\mathrm{GeV}{}^{2}$. To extend this gluon density to higher ${Q}^{2}$ we apply the Catani-Ciafoloni-Fiorani-Marchesini evolution equation. The influence of the initial (starting) nonperturbative gluon distribution is studied. The application of the obtained gluon density to the analysis of the deep inelastic $ep$ scattering allows us to get the results which describe reasonably well the H1 and ZEUS data on the longitudinal proton structure function ${F}_{L}(x,{Q}^{2})$. So, the connection between the soft processes at the LHC and small-$x$ physics at HERA has been confirmed and extended to a wide kinematical region.