Model-independent diagnostic of self-induced spectral equalization versus ordinary matter effects in supernova neutrinos

TL;DR

This paper proposes a model-independent method to distinguish self-induced spectral equalization from matter effects in supernova neutrino signals using ratios of different detection channels at next-generation detectors.

Contribution

It introduces a novel analysis strategy that compares charged-current and neutral-current events without relying on spectral modeling to identify flavor equalization.

Findings

The method can differentiate flavor equalization from matter effects in supernova neutrino signals.

It is effective across different neutrino mass orderings.

The approach is robust as long as spectral differences among neutrino species are not too small.

Abstract

Self-induced flavor conversions near the supernova (SN) core can make the fluxes for different neutrino species become almost equal, potentially altering the dynamics of the SN explosion and washing out all further neutrino oscillation effects. We present a new model-independent analysis strategy for the next galactic SN signal that will distinguish this flavor equalization scenario from a matter effects only scenario during the SN accretion phase. Our method does not rely on fitting or modelling the energy-dependent fluences of the different species to a known function, but rather uses a model-independent comparison of charged-current and neutral-current events at large next-generation underground detectors. Specifically, we advocate that the events due to elastic scattering on protons in a scintillator detector, which is insensitive to oscillation effects and can be used as a model-independent normalization, should be compared with the events due to inverse beta decay of $\bar\nu_e$ in a water Cherenkov detector and/or the events due to charged-current interactions of $\nu_e$ in an Argon detector. The ratio of events in these different detection channels allow one to distinguish a complete flavor equalization from a pure matter effect, for either of the neutrino mass orderings, as long as the spectral differences among the different species are not too small.