Charged Current Neutrino Cross Section and Tau Energy Loss at Ultra-High Energies

摘要

We evaluate both the tau lepton energy loss produced by photonuclearinteractions and the neutrino charged current cross section at ultra-highenergies, relevant to neutrino bounds with Earth-skimming tau neutrinos, usingdifferent theoretical and phenomenological models for nucleon and nucleusstructure functions. The theoretical uncertainty is estimated by takingdifferent extrapolations of the structure function F2 to very low values of x,in the low and moderate Q2 range for the tau lepton interaction and at high Q2for the neutrino-nucleus inelastic cross section. It is at these extremely lowvalues of x where nuclear shadowing and parton saturation effects are unknownand could be stronger than usually considered. For tau and neutrino energiesE=10^9 GeV we find uncertainties of a factor 4 for the tau energy loss and of afactor 2 for the charged current neutrino-nucleus cross section.