The Sun and core-collapse supernovae are leading probes of the neutrino lifetime

Abstract: The large distances travelled by neutrinos emitted from the Sun and core-collapse supernovae together with the characteristic energy of such neutrinos provide ideal conditions to probe their lifetime, when the decay products evade detection. We investigate the prospects of probing invisible neutrino decay capitalising on the detection of solar and supernova neutrinos as well as the diffuse supernova neutrino background (DSNB) in the next-generation neutrino observatories Hyper-Kamiokande, DUNE, JUNO, DARWIN, and RES-NOVA. We find that future solar neutrino data will be sensitive to values of the lifetime-to-mass ratio $\tau_1/m_1$ and $\tau_2/m_2$ of $\mathcal{O}(10^{-1} - 10^{-2})$ s/eV. From a core-collapse supernova explosion at $10$ kpc, lifetime-to-mass ratios of the three mass eigenstates of $\mathcal{O}(10^5)$ s/eV could be tested. After $20$ years of data taking, the DSNB would extend the sensitivity reach of $\tau_1/m_1$ to $10^{8}$ s/eV. These results promise an improvement of about $6 -15$ orders of magnitude on the values of the decay parameters with respect to existing limits.