Probing neutrino coupling to a light scalar with coherent neutrino scattering

TL;DR

Future coherent neutrino scattering experiments can precisely probe light scalar particles coupled to neutrinos and quarks, setting new limits and potentially determining scalar masses through spectral distortions.

Contribution

This paper analyzes current and future experimental limits on light scalar particles coupled to neutrinos and quarks, including model considerations and comparison with other constraints.

Findings

Current experiments probe scalar masses of a few MeV down to couplings of 10^{-4}.

Future experiments can reach couplings of 10^{-6}.

Scalar mass can be determined from spectral shape distortions.

Abstract

Large neutrino event numbers in future experiments measuring coherent elastic neutrino nucleus scattering allow precision measurements of standard and new physics. We analyze the current and prospective limits of a light scalar particle coupling to neutrinos and quarks, using COHERENT and CONUS as examples. Both lepton number conserving and violating interactions are considered. It is shown that current (future) experiments can probe for scalar masses of a few MeV couplings down to the level of $10^{-4}$ $(10^{-6})$. Scalars with masses around the neutrino energy allow to determine their mass via a characteristic spectrum shape distortion. Our present and future limits are compared with constraints from supernova evolution, Big Bang nucleosynthesis and neutrinoless double beta decay. We also outline UV-complete underlying models that include a light scalar with coupling to quarks for both lepton number violating and conserving coupling to neutrinos.