Light Higgsinos for electroweak naturalness in mirage-mediated high-scale supersymmetry

TL;DR

This paper explores how mirage mediation in high-scale supersymmetry can naturally produce light Higgsinos, significantly reducing electroweak fine-tuning while maintaining gauge coupling unification and experimental constraints.

Contribution

It demonstrates that light Higgsinos in mirage mediation can lower electroweak fine-tuning in high-scale supersymmetry scenarios, a novel insight for naturalness.

Findings

Electroweak fine-tuning can be below a few percent with light Higgsinos.

Higgsinos around or below a few hundred GeV are compatible with experimental constraints.

Mirage mediation achieves low fine-tuning similar to weak scale supersymmetry.

Abstract

Mirage mediation realized in the Kachru-Kallosh-Linde-Trivedi (KKLT) flux compactification can naturally suppress the up-type Higgs soft mass at low energy scales. As a result, compared to the conventional scenarios, the degree of electroweak fine-tuning can be reduced further up to by a loop factor if the Higgsinos are much lighter than the heavy Higgs doublet. Interestingly, this feature holds even in high-scale supersymmetry as long as the gauge coupling unification, which is required as a prerequisite for mirage mediation, accommodates such light Higgsinos. Under the experimental constraints on the observed Higgs boson, it turns out that mirage mediation can exhibit low electroweak fine-tuning better than a few percent for stops between about 2 and 6 TeV, i.e., at the same level as in the weak scale supersymmetry, if the Higgsinos are around or below a few hundred GeV.