Decay of High-Energy Astrophysical Neutrinos

Abstract

Existing limits on the non-radiative decay of one neutrino to another plus a massless particle (e.g., a singlet Majoron) are very weak. The best limits on the lifetime to mass ratio come from solar neutrino observations, and are $\tau /m\text{agt}10^{-4}$ s/eV for the relevant mass eigenstate(s). For lifetimes even several orders of magnitude longer, high-energy neutrinos from distant astrophysical sources would decay. This would strongly alter the flavor ratios from the ${\varphi }_{{\nu }_e}:{\varphi }_{{\nu }_{\mu }}:{\varphi }_{{\nu }_{\tau }}=1:1:1$ expected from oscillations alone, and should be readily visible in the near future in detectors such as IceCube.

Comments: 4 pages, 1 figure. References added. Version to appear in PRL