Sensitivity of Future Tritium Decay Experiments to New Physics

TL;DR

Future tritium beta-decay experiments using advanced spectroscopy and atomic tritium could significantly improve sensitivity to keV-mass sterile neutrinos and exotic neutrino interactions, enabling new physics discoveries.

Contribution

This paper provides detailed sensitivity analyses for future tritium decay experiments targeting sterile neutrinos and exotic interactions, incorporating decay distributions and atomic effects.

Findings

Projected sensitivity to active-sterile neutrino mixing improves by an order of magnitude.

Potential to detect or constrain exotic neutrino interactions.

Analysis includes decay distributions with atomic and polarization effects.

Abstract

Tritium beta-decay is the most promising approach to measure the absolute masses of active light neutrinos in the laboratory and in a model-independent fashion. The development of Cyclotron Radiation Emission Spectroscopy techniques and the use of atomic tritium has the potential to improve the current limits by an order of magnitude in future experiments. In this paper, we analyse the potential sensitivity of such future searches to keV-mass sterile neutrinos and exotic interactions of either the active or sterile neutrinos. We calculate the relevant decay distributions in both energy and angle of the emitted electron with respect to a potential polarisation of the tritium, including the interference with the Standard Model case as well as incorporating relevant final state corrections for atomic tritium. We present projected sensitivities on the active-sterile neutrino mixing and effective coupling constants of exotic currents, demonstrating the potential to probe New Physics in tritium experiments.