Constraining Nonstandard Neutrino-Electron Interactions

TL;DR

This paper analyzes nonstandard neutrino-electron interactions using data from accelerators, reactors, and LEP, improving existing constraints and highlighting the need for future experiments to further narrow down NSI parameters.

Contribution

It provides a comprehensive global analysis of neutrino-electron NSI parameters, combining diverse datasets to tighten constraints and address degeneracies.

Findings

Most constraints on NSI parameters are improved compared to previous results.

Degeneracies in flavor-conserving NSI parameters are effectively removed through combined data analysis.

Significant parameter space remains, indicating the necessity for future experimental efforts.

Abstract

We present a detailed analysis on nonstandard neutrino interactions (NSI) with electrons including all muon and electron (anti)-neutrino data from existing accelerators and reactors, in conjunction with the ``neutrino counting'' data (e- e+ -> nu nu gamma) from the four LEP collaborations. First we perform a one-parameter-at-a-time analysis, showing how most constraints improve with respect to previous results reported in the literature. We also present more robust results where the NSI parameters are allowed to vary freely in the analysis. We show the importance of combining LEP data with the other experiments in removing degeneracies in the global analysis constraining flavor-conserving NSI parameters which, at 90 % and 95 % C.L., must lie within unique allowed regions. Despite such improved constraints, there is still substantial room for improvement, posing a big challenge for upcoming experiments.