# Light Higgsino for Gauge Coupling Unification

## TL;DR

This paper investigates how light higgsinos in high-scale supersymmetry can enable precise gauge coupling unification and provide dark matter candidates, with implications for supersymmetry breaking mechanisms.

## Contribution

It demonstrates that light higgsinos allow gauge coupling unification at high scales and connects this to dark matter and specific supersymmetry breaking models.

## Key findings

- Gauge couplings unify as precisely as in low-energy supersymmetry.
- Dark matter can be explained by neutral higgsino or gravitino.
- High scale supersymmetry with light higgsinos is naturally realized in anomaly and gauge mediation models.

## Abstract

We explore gauge coupling unification and dark matter in high scale supersymmetry where the scale of supersymmetry breaking is much above the weak scale. The gauge couplings unify as precisely as in low energy supersymmetry if the higgsinos, whose mass does not break supersymmetry, are much lighter than those obtaining masses from supersymmetry breaking. The dark matter of the universe can then be explained by the neutral higgsino or the gravitino. High scale supersymmetry with light higgsinos requires a large Higgs mixing parameter for electroweak symmetry breaking to take place. It is thus naturally realized in models where superparticle masses are generated at loop level while the Higgs mixing parameter is induced at tree level, like in anomaly and gauge mediation of supersymmetry breaking.