# Prospects for axion detection in natural SUSY with mixed axion-higgsino dark matter: back to invisible?

## TL;DR

This paper explores the detectability of axions in natural supersymmetry models with mixed axion-higgsino dark matter, highlighting challenges due to suppressed couplings and proposing the need for innovative detection techniques.

## Contribution

It introduces a model combining SUSY and PQ symmetry, analyzes axion detection prospects, and discusses the impact of higgsino contributions on axion couplings and visibility.

## Key findings

- Axion detection rates are suppressed due to higgsino contributions.
- Allowed axion mass range is constrained by WIMP detection limits.
- Axions may become nearly invisible in current detection regimes.

## Abstract

Under the expectation that nature is natural, we extend the Standard Model to include SUSY to stabilize the electroweak sector and PQ symmetry to stabilize the QCD sector. Then natural SUSY arises from a Kim-Nilles solution to the SUSY mu problem which allows for a little hierarchy where mu ~ f_a^2/M_P ~ 100-300 GeV while the SUSY particle mass scale m(SUSY)~ 1-10 TeV >> mu. Dark matter then consists of two particles: a higgsino-like WIMP and a SUSY DFSZ axion. The range of allowed axion mass values m(axion) depends on the mixed axion-higgsino relic density. The range of m(axion) is actually restricted in this case by limits on WIMPs from direct and indirect detection experiments. We plot the expected axion detection rate at microwave cavity experiments. The axion-photon-photon coupling is severely diminished by charged higgsino contributions to the anomalous coupling. In this case, the axion may retreat, at least temporarily, back into the regime of near invisibility. From our results, we urge new ideas for techniques which probe both deeper and more broadly into axion coupling versus axion mass parameter space.