Higgsinos in SUSY Models with Gaugino Mass Unification

TL;DR

This paper investigates the conditions under which Higgsinos can be the lightest neutralinos in SUSY models, emphasizing the impact of gaugino mass unification and the tuning of Higgs mass parameters.

Contribution

It demonstrates that gaugino mass unification favors gaugino-like neutralinos and shows the fine-tuning needed for Higgsino-like neutralinos within these models.

Findings

Gaugino mass unification leads to gaugino-like neutralinos.

Small mu parameter requires precise tuning of m_Hu.

Gaugino-like neutralinos are preferred in unified models.

Abstract

In the MSSM, the assumptions of a common sfermion mass parameter m_0 and a common gaugino mass parameter m_1/2, along with the requirements from radiative electroweak symmetry breaking, lead to relatively large values of the Higgs mixing parameter mu, and consequently to a gaugino-like lightest neutralino. Lifting the requirement that the Higgs mass parameters unify with the sfermion masses is known to allow for smaller mu. We show that a mu parameter sufficiently small to yield a Higgsino-like neutralino requires a precise adjustment of the Higgs mass parameter m_Hu. Consequently a gaugino-type neutralino is still preferred in SUSY models with gaugino mass unification.