Probing BSM Neutrino Physics with Flavor and Spectral Distortions: Prospects for Future High-Energy Neutrino Telescopes

The flavor of cosmic neutrinos may help unveil their sources and could reveal the presence of new physics in the neutrino sector. We consider the impacts of next-generation neutrino detectors, including the planned upgrade to neutrino detector--IceCube-Gen2, which is well-positioned to make dramatic improvements in both flavor and spectral measurements. We show that various models in neutrino physics beyond the Standard Model, such as neutrino decay, pseudo-Dirac states, and neutrino self-scattering, may be found or strongly constrained at IceCube-Gen2 and KM3NeT. We find that the additional flavor discriminants given by Glashow resonance events and so-called "double-bang" topologies improve the ability to access the flavor of the cosmic high-energy neutrinos and probe the BSM physics. In addition, although the details depend on source properties, Glashow resonance events have the additional feature of being able to inform us of the relative strengths of neutrino and antineutrino emission, which may help us discriminate astrophysical scenarios.