Light Higgsinos in Pure Gravity Mediation

TL;DR

This paper explores an extension of pure gravity mediation models allowing a light Higgsino as the dark matter candidate, analyzing the parameter space and implications for supersymmetric particle spectra and dark matter composition.

Contribution

It introduces a flexible $$-term in PGM models, enabling a Higgsino LSP and diverse dark matter scenarios, including axions and various neutralinos.

Findings

Higgsino can be the lightest supersymmetric particle in extended PGM models.

Dark matter may be composed of axions, winos, binos, or Higgsinos depending on parameters.

The model remains consistent with electroweak symmetry breaking and Higgs mass measurements.

Abstract

Pure gravity mediation (PGM), with two free parameters, is a minimalistic approach to supergravity models, yet is capable of incorporating radiative electroweak symmetry breaking, a Higgs mass in agreement with the experimental measurement, without violating any phenomenological constraints. The model may also contain a viable dark matter candidate in the form of a wino. Here, we extend the minimal model by allowing the $\mu$-term to be a free parameter (equivalent to allowing the two Higgs soft masses, $m_1$ and $m_2$, to differ from other scalar masses) which are set by the gravitino mass. In particular, we examine the region of parameter space where $\mu \ll m_{3/2}$ in which case, the Higgsino becomes the lightest supersymmetric particle (LSP) and a dark matter candidate. We also consider a generalization of PGM which incorporates a Peccei-Quinn symmetry which determines the $\mu$-term dynamically. In this case, we show that the dark matter may either be in the form of an axion and/or a neutralino, and that the LSP may be either a wino, bino, or Higgsino.