Spin-flavor oscillations of ultrahigh-energy cosmic neutrinos in interstellar space: The role of neutrino magnetic moments

TL;DR

This paper provides an exact theoretical analysis of how neutrino magnetic moments could influence the flavor and spin oscillations of ultrahigh-energy cosmic neutrinos traveling through interstellar space, considering two-neutrino mixing.

Contribution

It derives an exact solution for neutrino evolution equations in magnetic fields and matter, incorporating four neutrino states with different helicities, and applies it to astrophysical neutrino scenarios.

Findings

Patterns of spin-flavor oscillations depend on neutrino energy.

Probabilities of oscillations are calculated using astrophysical bounds on magnetic moments.

Results are relevant for cosmogenic neutrinos and GZK cutoff energies.

Abstract

A theoretical analysis of possible influence of neutrino magnetic moments on the propagation of ultrahigh-energy cosmic neutrinos in the interstellar space is carried out under the assumption of two-neutrino mixing. The exact solution of the effective equation for neutrino evolution in the presence of a magnetic field and matter is obtained, which accounts for four neutrino species corresponding to two different flavor states with positive and negative helicities. Using most stringent astrophysical bounds on the putative neutrino magnetic moment, probabilities of neutrino flavor and spin oscillations are calculated on the basis of the obtained exact solution. Specific patterns of spin-flavor oscillations are determined for neutrino-energy values characteristic of, respectively, the cosmogenic neutrinos, the Greisen-Zatsepin-Kuz'min (GZK) cutoff, and well above the cutoff.