Light Higgsino as the tail of the $\mu$-$B_\mu$ solution

TL;DR

This paper explores how a light Higgsino around 100 GeV naturally arises in gauge mediation models with heavy squarks, providing a potential experimental signature despite the high SUSY scale.

Contribution

It demonstrates that a simple naive solution to the $ppa$ problem can produce a light Higgsino in models with heavy squarks, under slight GUT relation breaking.

Findings

Light Higgsino around 100 GeV is compatible with gauge mediation.

Heavy squarks (~10 TeV) explain the 125 GeV Higgs mass.

Upper bounds on Higgsino mass derived from multiple theoretical constraints.

Abstract

Gauge mediation predicts 10 TeV or heavier squarks because such a heavy stop is required to explain the observed 125 GeV Higgs boson mass without a large trilinear soft mass term in the minimal supersymmetric standard model. Although such a high scale cannot be searched by the LHC directly, gauge mediation also predicts a hierarchy $\mu^2 \ll B_\mu$ by a simple and naive solution of the $\mu$ problem. We point out that this simple and naive way of generating the $\mu$ ($B_\mu$) term works in the case of 10 TeV or heavier squarks with a slight breaking of a GUT relation among messenger B-terms (or supersymmetric mass terms). Furthermore, the upper bound on the Higgsino mass is obtained from the observed Higgs boson mass, perturbativity of a relevant coupling, and conditions avoiding tachyonic sneutrinos and stop. It turns out that the light Higgsino of O(100) GeV is a promising signal of gauge mediation.