Searching for the light dark gauge boson in GeV-scale experiments

TL;DR

This paper evaluates current constraints and future search strategies for a GeV-scale dark gauge boson, highlighting the superior potential of dedicated fixed target experiments over collider and meson decay searches.

Contribution

It proposes optimized fixed target experiment designs to effectively explore the parameter space of the light dark gauge boson.

Findings

Collider and meson decay searches can potentially discover or exclude the particle at higher coupling strengths.

Dedicated fixed target experiments offer significantly better sensitivity for lower coupling strengths.

Two optimal fixed target experiment designs are outlined for different coupling strength ranges.

Abstract

We study current constraints and search prospects for a GeV scale vector boson at a range of low energy experiments. It couples to the Standard Model charged particles with a strength <= 10^-3 to 10^-4 of that of the photon. The possibility of such a particle mediating dark matter self-interactions has received much attention recently. We consider searches at low energy high luminosity colliders, meson decays, and fixed target experiments. Based on available data, searches both at colliders and in meson decays can discover or exclude such a scenario if the coupling strength is on the larger side. We emphasize that a dedicated fixed target experiment has a much better potential in searching for such a gauge boson, and outline the desired properties of such an experiment. Two different optimal designs should be implemented to cover the range of coupling strength 10^-3 to 10^-5, and < 10^-5 of the photon, respectively. We also briefly comment on other possible ways of searching for such a gauge boson.