A decay of the ultra-high-energy neutrino $\nu_e \to e^- W^+$ in a magnetic field and its influence on the shape of the neutrino spectrum

TL;DR

This paper calculates the decay width and mean free path of ultra-high-energy neutrinos in strong magnetic fields, correcting previous formulas and defining an energy cutoff affecting neutrino spectra.

Contribution

It provides corrected formulas for neutrino decay in magnetic fields and introduces an energy cutoff impacting neutrino propagation models.

Findings

Corrected decay width formulas for neutrinos in magnetic fields

Calculated mean free path of ultra-high-energy neutrinos

Defined an energy cutoff influencing neutrino spectrum shape

Abstract

The width of the neutrino decay into the electron and $W$ boson in a strong external magnetic field is obtained from the imaginary part of the neutrino self-energy. This result corrects the formulae existing in the literature. The mean free path of an ultra-high energy neutrino in a strong magnetic field is calculated. An energy cutoff for neutrinos propagating in a strong field is defined.