Earth skimming tau neutrino propagation: structure function parametrization and dipole model

We consider the high energy Earth skimming tau neutrinos converting to taus following by tau propagation through rock. The difficulty in predict the final tau flux comes from the theoretical uncertainties in the tau electromagnetic energy loss and the neutrino-nucleon cross section. The first part of the thesis focuses on deriving the dipole cross section from a theoretical parametrization of the electromagnetic structure function, then uses said cross section to compute the tau's energy loss at high energies during Earth propagation. We find the extracted dipole cross section agrees well with other derivation and dipole models. In the second part, we use different approaches to the structure function $F_2$ and the dipole model to evaluate the corresponding energy loss and cross section. We keep consistent the same approach through both calculations of energy loss and neutrino cross section, and find the emerging tau fluxes match well. We also present the results from our Monte Carlo simulation and our analytic evaluation, and we find that they are in agreement. Finally, we briefly discuss the relevence to several experiments that are looking for skimming astrophysical taus, such as the Pierre Auger Observatory, HAWC, and ASHRA. As a quick demonstration, we show our approximation of the aperture at the Pierre Auger using the energy losses and cross sections calculated from the considered approaches.