Mainly axion cold dark matter from natural supersymmetry

TL;DR

This paper explores a natural supersymmetry model where dark matter predominantly consists of axions with a smaller higgsino-like WIMP component, predicting detectable signals in direct detection experiments.

Contribution

It introduces a model combining axion and higgsino-like WIMP dark matter within natural supersymmetry, addressing the SUSY mu problem via the Kim-Nilles mechanism.

Findings

Dark matter is mainly axions (90-95%) over a broad Peccei-Quinn scale range.

Both axion and WIMP direct detection are potentially observable.

The model avoids fine-tuning in electroweak and QCD sectors.

Abstract

By eschewing finetuning from the electroweak and QCD sectors of supersymmetry (natural supersymmetry or SUSY), and by invoking the Kim-Nilles solution to the SUSY mu problem, one is lead to models wherein the dark matter is comprised of a mixture of axions and higgsino-like WIMPs. Over a large range of Peccei-Quinn breaking scale f_a~ 10^9-10^{12} GeV, one then expects about 90-95% axion dark matter. In such a scenario, both axion and WIMP direct detection may be expected.