On the Possibility to Determine Neutrino Mass Hierarchy via Supernova Neutrinos with Short-Time Characteristics

TL;DR

This study explores the potential to determine the neutrino mass hierarchy by analyzing short-time characteristics of supernova neutrino signals in large detectors, considering different supernova scenarios and their detectability.

Contribution

It proposes a method to identify neutrino mass hierarchy using timing differences in supernova neutrino signals, considering realistic detector sizes and supernova distances.

Findings

Discrimination is possible only for supernovae within a few Mpc with gigaton detectors.

Neutronization burst signals offer limited discrimination due to low statistics.

Black hole formation signals could allow hierarchy determination under specific conditions.

Abstract

In this paper, we investigate whether it is possible to determine the neutrino mass hierarchy via a high-statistics and real-time observation of supernova neutrinos with short-time characteristics. The essential idea is to utilize distinct times-of-flight for different neutrino mass eigenstates from a core-collapse supernova to the Earth, which may significantly change the time distribution of neutrino events in the future huge water-Cherenkov and liquid-scintillator detectors. For illustration, we consider two different scenarios. The first case is the neutronization burst of $\nu^{}_e$ emitted in the first tens of milliseconds of a core-collapse supernova, while the second case is the black hole formation during the accretion phase for which neutrino signals are expected to be abruptly terminated. In the latter scenario, it turns out only when the supernova is at a distance of a few Mpc and the fiducial mass of the detector is at the level of gigaton, might we be able to discriminate between normal and inverted neutrino mass hierarchies. In the former scenario, the probability for such a discrimination is even less due to a poor statistics.