A COHERENT enlightenment of the neutrino Dark Side

TL;DR

This paper demonstrates that recent coherent neutrino--nucleus scattering data, combined with oscillation data, effectively resolves degeneracies caused by non-standard neutrino interactions, clarifying neutrino mass ordering.

Contribution

It shows that combining COHERENT experiment results with global data excludes NSI-induced degeneracies at over 3 sigma confidence levels.

Findings

COHERENT data constrains NSI parameters significantly.

Degeneracy in neutrino oscillation data is resolved.

Neutrino mass ordering ambiguity is reduced.

Abstract

In the presence of non-standard neutrino interactions (NSI), oscillation data are affected by a degeneracy which allows the solar mixing angle to be in the second octant (aka the dark side) and implies a sign flip of the atmospheric mass-squared difference. This leads to an ambiguity in the determination of the ordering of neutrino masses, one of the main goals of the current and future experimental neutrino program. We show that the recent observation of coherent neutrino--nucleus scattering by the COHERENT experiment, in combination with global oscillation data, excludes the NSI degeneracy at the $3.1\sigma$ ($3.6\sigma$) CL for NSI with up (down) quarks.