Flavor Triangle of the Diffuse Supernova Neutrino Background

TL;DR

This paper analyzes the potential to reconstruct the flavor composition of the diffuse supernova neutrino background using future detectors, testing oscillation physics and exploring scenarios like MSW and neutrino decay.

Contribution

It provides estimates of how well upcoming experiments can determine the DSNB flavor content, including the impact of different oscillation scenarios.

Findings

Large fraction of flavor space can be constrained.

Heavy-lepton neutrino flux remains difficult to measure.

Future detectors will improve understanding of neutrino oscillations.

Abstract

Although Galactic core-collapse supernovae (SNe) only happen a few times per century, every hour a vast number of explosions happen in the whole universe, emitting energy in the form of neutrinos, resulting in the diffuse supernova neutrino background (DSNB). The DSNB has not yet been detected, but Super-Kamiokande doped with gadolinium is expected to yield the first statistically significant observation within the next several years. Since the neutrinos produced at the core collapse undergo mixing during their propagation to Earth, the flavor content at detection is a test of oscillation physics. In this paper, we estimate the expected DSNB data at the DUNE, Hyper-K and JUNO experiments which when combined are sensitive to all different neutrino flavors. We determine how well the flavor content of the DSNB will be reconstructed in the future, for a Mikheyev-Smirnov-Wolfenstein (MSW) scenario as well as a neutrino decay scenario. A large fraction of the flavor space will be excluded, but the heavy-lepton neutrino flux remains a challenge.