# $Z'$ Mediated WIMPs: Dead, Dying, or Soon to be Detected?

## TL;DR

This paper evaluates the current status of Z'-mediated WIMP dark matter models, finding that despite constraints, a significant parameter space remains viable and future experiments could test much of it.

## Contribution

The study provides a comprehensive analysis of Z'-mediated WIMP models, quantifies excluded versus viable parameter space, and highlights the potential of future experiments to probe remaining models.

## Key findings

- A sizable fraction of parameter space remains viable for Z'-mediated WIMPs.
- Current experiments exclude only part of the parameter space, especially for Majorana fermions.
- Future direct detection experiments near the neutrino floor can test much of the remaining viable models.

## Abstract

Although weakly interacting massive particles (WIMPs) have long been among the most studied and theoretically attractive classes of candidates for the dark matter of our universe, the lack of their detection in direct detection and collider experiments has begun to dampen enthusiasm for this paradigm. In this study, we set out to appraise the status of the WIMP paradigm, focusing on the case of dark matter candidates that interact with the Standard Model through a new gauge boson. After considering a wide range of $Z'$ mediated dark matter models, we quantitatively evaluate the fraction of the parameter space that has been excluded by existing experiments, and that is projected to fall within the reach of future direct detection experiments. Despite the existence of stringent constraints, we find that a sizable fraction of this parameter space remains viable. More specifically, if the dark matter is a Majorana fermion, we find that an order one fraction of the parameter space is in many cases untested by current experiments. Future direct detection experiments with sensitivity near the irreducible neutrino floor will be able to test a significant fraction of the currently viable parameter space, providing considerable motivation for the next generation of direct detection experiments.