First constraints on general neutrino interactions based on KATRIN data

TL;DR

This paper uses KATRIN's precise tritium beta-decay measurements to set the first experimental constraints on general neutrino interactions within an effective field theory framework, exploring potential new physics signals.

Contribution

It formulates an effective description of GNI effects on the beta spectrum and derives the first constraints on these parameters from KATRIN data, including specific new physics scenarios.

Findings

First constraints on GNI parameters from KATRIN data

Constraints on right-handed W boson, charged Higgs, and leptoquarks

Demonstrates KATRIN's potential to probe new physics

Abstract

The precision measurement of the tritium $\beta$-decay spectrum performed by the KATRIN experiment provides a unique way to search for general neutrino interactions (GNI). All theoretical allowed GNI terms involving neutrinos are incorporated into a low-energy effective field theory, and can be identified by specific signatures in the measured tritium $\beta$-spectrum. In this paper an effective description of the impact of GNI on the $\beta$-spectrum is formulated and the first constraints on the effective GNI parameters are derived based on the 4 million electrons collected in the second measurement campaign of KATRIN in 2019. In addition, constraints on selected types of interactions are investigated, thereby exploring the potential of KATRIN to search for more specific new physics cases, including a right-handed W boson, a charged Higgs or leptoquarks.