Monophotons at Neutrino Experiments from Neutrino Polarizability

TL;DR

This paper explores how monophoton signals at neutrino experiments can be used to detect neutrino polarizability, a potential sign of physics beyond the Standard Model involving new particles like ALPs and Majorons.

Contribution

It introduces a novel approach to probe neutrino electromagnetic properties via monophoton signals and provides current and future experimental constraints on neutrino polarizability.

Findings

NOMAD and MiniBooNE set the strongest current limits.

SBND and DUNE will significantly improve constraints.

Photon energy and angular distributions are key to detection.

Abstract

Nontrivial electromagnetic properties of neutrinos are an avenue to physics beyond the Standard Model. To this end, we investigate the power of monophoton signals at neutrino experiments to probe a higher-dimensional operator connecting neutrinos to SM photons dubbed, neutrino polarizability. A simplified scenario giving rise to this operator involves a new pseudo-scalar that couples to both neutrinos and photons, with clear implications for axion-like particle (ALP) and Majoron physics. By analyzing the photon energy spectrum and angular distributions, we find that NOMAD and MiniBooNE currently set the most stringent limits, while SBND and the DUNE near detector will soon provide significantly improved constraints.