Tritium beta decay with modified neutrino dispersion relations: KATRIN in the dark sea

TL;DR

This paper investigates how dark sector fields could modify neutrino dispersion relations, affecting tritium beta decay spectra and potentially mimicking neutrino mass signals, with implications for KATRIN experiment constraints.

Contribution

It introduces a framework for dark sector-induced modifications to neutrino dispersion relations and analyzes their effects on beta decay spectra, providing new constraints from KATRIN data.

Findings

Vector and axial-vector potentials shift the electron energy spectrum.

Scalar and pseudoscalar potentials can mimic neutrino mass effects.

Current KATRIN data impose stringent limits on dark sector potentials.

Abstract

We explore beta decays in a dark background field, which could be formed by dark matter, dark energy or a fifth force potential. In such scenarios, the neutrino's dispersion relation will be modified by its collective interaction with the dark field, which can have interesting consequences in experiments using tritium beta decays to determine the absolute neutrino mass. Among the most general interaction forms, the (pseudo)scalar and (axial-)vector ones are found to have interesting effects on the spectrum of beta decays. In particular, the vector and axial-vector potentials can induce distinct signatures by shifting the overall electron energy scale, possibly beyond the usually defined endpoint. The scalar and pseudoscalar potentials are able to mimic a neutrino mass beyond the cosmological bounds. We have placed stringent constraints on the dark potentials based on the available experimental data of KATRIN. The sensitivity of future KATRIN runs is also discussed.