Neutrino nonradiative decay and the diffuse supernova neutrino background

We revisit the possibility that neutrinos undergo nonradiative decay. We investigate the potential to extract information on the neutrino lifetime-to-mass ratio from the diffuse supernova neutrino background. To this aim, we explicitly consider the current uncertainties on the core-collapse supernova rate and the fraction of failed supernovae. We present predictions in a full $3\ensuremath{\nu}$ framework in the absence and presence of neutrino nonradiative decay, for the Super-Kamiokande+Gd, the JUNO, the Hyper-Kamiokande, and the DUNE experiments, that should observe the diffuse supernova neutrino background in the near future. Our results show the importance of a $3\ensuremath{\nu}$ treatment of neutrino decay and of identifying the neutrino mass ordering to break possible degeneracies between diffuse supernova neutrino background predictions in the presence of decay and standard physics.