Supersymmetry with Dark Matter is still natural

TL;DR

This paper shows that certain minimal supersymmetric models with dark matter candidates can be naturally fine-tuned and compatible with current astrophysical hints, with upcoming experiments poised to test these models.

Contribution

It identifies low-fine-tuning regions of the pMSSM with viable dark matter candidates and links fine-tuning to astrophysical signals and future experimental tests.

Findings

Low fine-tuning in pMSSM is compatible with LHC constraints.

Dark matter candidates are bino-higgsino particles of 35-155 GeV.

Upcoming experiments like XENON1T will test these natural models.

Abstract

We identify the parameter regions of the phenomenological minimal supersymmetric standard model (pMSSM) with the minimal possible fine-tuning. We show that the fine-tuning of the pMSSM is not large, nor under pressure by LHC searches. Low sbottom, stop and gluino masses turn out to be less relevant for low fine-tuning than commonly assumed. We show a link between low fine-tuning and the dark matter relic density. Fine-tuning arguments point to models with a dark matter candidate yielding the correct dark matter relic density: a bino-higgsino particle with a mass of $35-155$ GeV. Some of these candidates are compatible with recent hints seen in astrophysics experiments such as Fermi-LAT and AMS-02. We argue that upcoming direct search experiments, such as XENON1T, will test all of the most natural solutions in the next few years due to the sensitivity of these experiments on the spin-dependent WIMP-nucleon cross section.