Calculation of the TeV prompt muon component in very high energy cosmic ray showers

HEMAS-DPM is a Monte Carlo for the simulation of very high energy cosmic ray showers, which includes the DPMJET-II code based on the two component Dual Parton Model. DPMJET-II provides also charm production in agreement with data and, for p(perpendicular to) exceeding 5 GeV/c, with perturbative QCD results in proton-proton interactions. In this respect, a new scheme has been considered for the inclusive production of D mesons at large p(perpendicular to) in hadronic collisions in the framework of perturbative fragmentation functions, allowing an analysis at the Next to Leading Order (NLO) level which goes beyond the fixed O(alpha(s)(3)) perturbative theory of open charm production. We have applied HEMAS-DPM to the calculation of the prompt muon component for E(mu) greater than or equal to 1 TeV in air showers considering the two extreme cases of primary protons and Fe nuclei.