Flavor Ratios and Mass Hierarchy at Neutrino Telescopes

The observation of high-energy extraterrestrial neutrinos at IceCube represents the beginning of the era of neutrino astronomy. In this paper, we study the cosmic neutrino flavor ratios against the Dirac CP-violating phase at neutrino telescopes, taking into account the charged-current and neutral-current interactions at the detectors. We then demonstrate how to probe mass hierarchy at future neutrino telescopes by the precise measurements of the cosmic neutrino flavor ratios. We show that the sensitivity of our scheme is independent of the undetermined values of the Dirac CP-violating phase. We also explore the possible effects of active-sterile mixing, neutrino decay and pseudo-Dirac nature of neutrinos.