Resolving the LMA-dark NSI degeneracy with coherent neutrino-nucleus scattering

TL;DR

This paper explores how recent coherent neutrino-nucleus scattering data can help resolve degeneracies in neutrino oscillation parameters caused by non-standard interactions, proposing future experimental setups for definitive resolution.

Contribution

It demonstrates that current CEνNS data partially disfavor the degeneracy and identifies experimental conditions needed to fully resolve it with high significance.

Findings

Current data disfavors the degeneracy at 2σ level.

Future measurements with specific targets can resolve the degeneracy at >4σ.

A silicon target at ESS can achieve high-confidence resolution.

Abstract

In the presence of non-standard neutrino interactions (NSI), a degeneracy exists in neutrino oscillation data, which involves the flipping of the octant of the mixing angle ${\theta_{12}}$ and the type of the neutrino mass ordering. In this article, we revisit the status of this degeneracy in the light of recent data on coherent elastic neutrino-nucleus scattering (CE${\nu}$NS) from the COHERENT experiment. For general relative couplings to up and down quarks, the degeneracy is disfavoured at the $2{\sigma}$ level by the latest data but remains at a higher confidence level. We investigate the requirements of future CE${\nu}$NS measurements to resolve the degeneracy with high significance. We find that a measurement involving both, electron and muon neutrino flavours and a target with a neutron-to-proton ratio close to 1 is required. For example, an experiment with a silicon target at the European Spallation Source can resolve the degeneracy at more than $4{\sigma}$ for arbitrary relative couplings to up and down quarks.