We discuss possible observable features in high and ultrahigh energy neutrino fluxes due to active-sterile secret interactions mediated by a new pseudoscalar particle.
Active-sterile neutrino interactions become relevant at very different energy scales depending on the masses of the scalar mediator and of sterile neutrino. As consequence, the final active fluxes can present a measurable depletion observable in future experiments.
We adopted two prescriptions for the neutrino flux, namely high-energy represented by a power-law, and ultra high-energy with cosmological origin (cosmogenic) in order to take into account the multi-scale energy phenomenology, varying from $10^6$GeV up to $10^9$ GeV.
When the depletion is around $10^6$GeV, this effect could be very interesting for IceCube because it can produce a cutoff-like feature in the spectrum, which could potentially explain the lack of observed events above 10 PeV. For larger values of mediator and sterile masses, the depletion effect instead could be only visible at larger energy, around $10^9$GeV, with future experiments like GRAND.