Extreme scenarios of new physics in the UHE astrophysical neutrino flavour ratios

TL;DR

This paper explores how adding an energy-independent Hamiltonian to neutrino oscillation models can cause extreme deviations in expected astrophysical neutrino flavor ratios, indicating potential new physics beyond the standard model.

Contribution

It introduces a formalism relating new physics parameters to standard neutrino oscillation parameters and demonstrates the possibility of large flavor ratio deviations due to this new physics.

Findings

Large deviations in neutrino flavor ratios are possible with new physics.

High-energy neutrino experiments are more sensitive to these new physics effects.

The formalism links new physics parameters to standard oscillation parameters.

Abstract

We add an energy-independent Hamiltonian to the standard flavour oscillation one. This kind of physics might appear in theories where neutrinos couple differently to a plausible non-zero torsion of the gravitational field or more dramatically in the presence of CPT-violating physics in the flavour oscillations. If this contribution exists, experiments at higher energies are more sensitive to their free parameters, and flavour conversion could be severely modified. We show that this new physics modifies the neutrino mixing angles and find expressions that relate the new, effective, angles to the standard oscillation parameters \Delta_m_{ij}^2, \theta_{ij} and \delta_{CP}, and to the parameters in the new-physics Hamiltonian, within a three-neutrino formalism. We consider scenarios where the new parameters allow for extreme deviations of the expected neutrino flavour ratios at Earth from their standard values. We show that large departures of the standard flavour scenario are plausible, which would be a strong hint of the violation of a conserved symmetry.