QGSJET-III model of high energy hadronic interactions: The formalism

Abstract: The physics content of the QGSJET-III Monte Carlo generator of high energy hadronic collisions is described. In particular, a phenomenological implementation of higher twist corrections to hard parton scattering processes is discussed in some detail. Additionally addressed is the treatment of the so-called ``color fluctuation'' effects related to a decomposition of hadron wave functions into a number of Fock states characterized by different spatial sizes and different parton densities. Selected model results regarding the energy-dependence of the total, elastic, and diffractive proton-proton cross sections are presented.