Nonperturbative QCD effects in forward scattering at the LHC

Abstract

We study infrared contributions to semihard parton-parton interactions by considering an effective charge whose finite infrared behavior is constrained by a dynamical mass scale. Using an eikonal QCDbased model in order to connect this semihard parton-level dynamics to the hadron-hadron scattering, we obtain predictions for the proton-proton (pp) and antiproton-proton ( ¯pp) total cross sections, σpp; ¯pp tot , and the ratios of the real to imaginary part of the forward scattering amplitude, ρpp; ¯pp. We discuss the theoretical aspects of this formalism and consider the phenomenological implications of a class of energydependent form factors in the high-energy behavior of the forward amplitude. We introduce integral dispersion relations specially tailored to relate the real and imaginary parts of eikonals with energydependent form factors. Our results, obtained using a group of updated sets of parton distribution functions, are consistent with the recent data from the TOTEM, AUGER, and Telescope Array experiments.