On the propagation of skimming UHE tau leptons and tau neutrinos

We present interesting results for two processes of main importance when studying skimming tau neutrinos. First, the accuracy of the approximation of continuous energy losses of the tau lepton in matter is discussed through a comparison with a full stochastic framework. And then, we question the validity of neglecting the ντ regeneration, through multiple ντ↔τ conversions, using different scenarios for the neutrino-nucleon cross-sections and the tau energy losses.