Testing neutrino instability with active galactic nuclei

Abstract

Active galactic nuclei and gamma ray bursts at cosmological distances are sources of high-energy electron and muon neutrinos and provide a unique test bench for neutrino instability. The typical lifetime-to-mass ratio one can reach there is $\tau /m\sim 500Mpc/c{E}_{\nu }\sim 500$ s/eV. We study the rapid decay channel ${\nu }_i\to {\nu }_j+\varphi$, where $\varphi$ is a massless or very light scalar (possibly a Goldstone boson), and point out that one can test the coupling strength of $g_{ij}{\nu }_i{\nu }_j$ down to $g_{ij}\text{lsim}10^{-8}eV/m$ by measuring the relative fluxes of ${\nu }_e$, ${\nu }_{\mu }$ and ${\nu }_{\tau }$. This is orders of magnitude more stringent bound than what one can obtain in other phenomena, e.g. in neutrinoless double beta decay with scalar emission.

Comments: 3 pages