Higgsino Dark Matter in Pure Gravity Mediated Supersymmetry

TL;DR

This paper explores the potential for direct detection of Higgsino dark matter within pure gravity mediation models of supersymmetry, highlighting the parameter space where detection is feasible and constrained by current experiments.

Contribution

It introduces a one-parameter extension to minimal PGM models allowing Higgsino dark matter viability and analyzes its detectability in future experiments.

Findings

Higgsino dark matter is viable for gravitino masses around 1 PeV and specific parameter choices.

Current experiments constrain parts of the PGM parameter space.

Future experiments can probe much of the remaining parameter space.

Abstract

We consider the prospects for the direct detection of dark matter in pure gravity meditation (PGM) models of supersymmetry breaking. Minimal PGM models require only two parameters, the gravitino mass, $m_{3/2}$, which sets the UV mass for all scalar masses, and $\tan\beta$. Gaugino masses are generated through anomaly mediation. Typically the lightest supersymmetric state (the dark matter candidate) is a wino. Here, we consider a one-parameter extension of the minimal model by allowing the Higgs soft masses to deviate from universality. For simplicity, we take these to be equal and use the $\mu$-term as a surrogate. We also consider non-universal stop masses. When $|\mu| \sim 1$ TeV, the Higgsino is a viable dark matter candidate when the gravitino mass is of order $\sim 1$ PeV and $\tan\beta \simeq 2$. We calculate the spin-dependent and spin-independent cross sections for dark matter scattering on protons. For spin-independent scattering, existing experimental limits place constraints on the PGM parameter space. Much of the currently allowed parameter space lies above the irreducible neutrino background. Thus, future direct detection experiments will be able to probe much of the remaining PGM parameter space.