High Energy Neutrino Interactions

We study ultrahigh energy astrophysical neutrinos and their interactions within the Standard Model and beyond. We consider propagation of muon neutrinos, tau neutrinos that originate in $ν_μ\to ν_τ$ oscillations, and tau leptons produced in charged-current neutrino interactions. We show that high energy taus lose their energy through bremsstrahlung, pair production and photonuclear processes until they reach energy of $\sim 10^8$ GeV, bellow which they are more likely to decay. Neutrino interact...