Opportunities for probing $U(1)_{T3R}$ with light mediators

TL;DR

This paper explores how future experiments can test models where light right-handed fermions interact via a new $U(1)_{T3R}$ gauge symmetry, which could explain flavor scales and dark matter, and potentially account for COHERENT excess.

Contribution

It identifies the parameter space of $U(1)_{T3R}$ models that can be probed by upcoming experiments, highlighting the potential to confirm or exclude this new physics scenario.

Findings

Much of the allowed parameter space can be tested with future experiments.

A small region of parameter space remains untestable even with upcoming experiments.

The model can explain the COHERENT excess within current experimental bounds.

Abstract

We consider strategies for using new datasets to probe scenarios in which light right-handed SM fermions couple to a new gauge group, $U(1)_{T3R}$. This scenario provides a natural explanation for the light flavor sector scale, and a motivation for sub-GeV dark matter. There is parameter space which is currently allowed, but we find that much of it can be probed with future experiments. In particular, cosmological and astrophysical observations, neutrino experiments and experiments which search for displaced visible decay or invisible decay can all play a role. Still, there is a small region of parameter space which even these upcoming experiments will not be able to probe. This model can explain the observed 2.4-3$\sigma$ excess of events at the COHERENT experiment in the parameter space allowed by current laboratory experiments, but the ongoing/upcoming laboratory experiments will decisively probe this possibility.