Probing Active-Sterile Neutrino Transition Magnetic Moments with Photon Emission from CE$\nu$NS

TL;DR

This paper proposes a new method using photon emission in CEνNS experiments to detect transition magnetic moments between active and sterile neutrinos, offering improved constraints and insights into neutrino properties.

Contribution

It introduces a novel radiative upscattering process with photon emission as a probe for neutrino transition magnetic moments beyond current limits.

Findings

Photon emission can provide a new coincidence signal in CEνNS experiments.

The differential distributions may distinguish Dirac from Majorana sterile neutrinos.

The method can improve constraints on neutrino magnetic moments.

Abstract

In the presence of transition magnetic moments between active and sterile neutrinos, the search for a Primakoff upscattering process at coherent elastic neutrino-nucleus scattering (CE$\nu$NS) experiments can provide stringent constraints on the neutrino magnetic moment. We show that a radiative upscattering process with an emitted photon in the final state can induce a novel coincidence signal at CE$\nu$NS experiments that can also probe neutrino transition magnetic moments beyond existing limits. Furthermore, the differential distributions for such a radiative mode can also potentially be sensitive to the Dirac vs. Majorana nature of the sterile state mediating the process. This can provide valuable insights into the nature and mass generation mechanism of the light active neutrinos.