Short Baseline Reactor Antineutrino-Electron Scattering Experiments and Non-Standard Neutrino Interactions at Source and Detector

TL;DR

This study explores non-standard neutrino interactions in short-baseline reactor experiments, demonstrating current constraints and projecting significant improvements in sensitivity with upgraded detectors, especially for detector-based new physics.

Contribution

It extends analysis of non-standard interactions at the detector to include phase effects and source interactions, providing updated constraints and sensitivity projections for short-baseline experiments.

Findings

Current data constrains detector new physics at existing levels.

Source new physics constraints are at least ten times weaker than detector constraints.

Upgraded experiments could improve detector sensitivity by factors of 5 to 10.

Abstract

We investigate non-standard interaction effects in antineutrino-electron scattering experiments with baselines short enough to ignore standard oscillation phenomena. The setup is free of ambiguities from the interference between new physics and oscillation effects and is sensitive to both semileptonic new physics at the source and purely leptonic new physics in the weak interaction scattering at the detector. We draw on the TEXONO experiment as the model system, extending its analysis of non-standard interaction effects at the detector to include the generally allowed non-standard interaction phase at the detector and both non-universal and flavor changing new physics at the reactor source. We confirm that the current data allows for new physics constraints at the detector of the same order as those currently published, but we find that constraints on the source new physics are at least an order of magnitude weaker. The new physics phase effects are at the 5% level, noticeable in the 90% C.L. contour plots but not significantly affecting the conclusions. Based on projected increase in sensitivity with an upgraded TEXONO experiment, we estimate the improvement of sensitivity to both source and detector non-standard interactions. We find that the bounds on source parameters improve by an order of magnitude, but do not reach parameter space beyond current limits. On the other hand, the detector new physics sensitivity would push current limits by factors 5 to 10 smaller.