Diffuse Supernova Neutrino Background and neutrino non-radiative decay: a Bayesian perspective

Abstract Neutrinos being massive could undergo non-radiative decay, a property for which the diffuse supernova neutrino background has a unique sensitivity. We extend previous analyses to explore our ability to disentangle predictions for the diffuse supernova neutrino background in presence or absence of neutrino non-radiative two-body decay. In a three-neutrino framework, we give predictions of the corresponding neutrino fluxes and the expected number of events in the Super-Kamiokande+Gadolinium, the Hyper-Kamiokande, the JUNO and the DUNE experiments. In our analysis, we employ supernova simulations from different groups and include current uncertainties from both the evolving core-collapse supernova rate and the fraction of failed supernovae. We perform the first Bayesian analysis to see our ability to disentangle the cases in presence and absence of neutrino decay. To this aim we combine the expected events in inverse beta-decay and the neutrino-argon detection channels. Our investigation covers the different possible decay patterns for normal mass ordering, both strongly-hierarchical and quasi-degenerate as well as the inverted neutrino mass ordering. In particular, for the case of normal mass ordering and strongly hierarchical mass pattern, we find that combining the DSNB detection channels in the different detectors does not suffice to break the degeneracies between the no decay and the decay cases.