The curtain lowers on directly detectable higgsino dark matter

TL;DR

This paper analyzes the constraints on higgsino dark matter from direct detection experiments, especially LUX-ZEPLIN, establishing bounds on gaugino masses and higgsino mass splittings, and discusses future detection challenges.

Contribution

It provides updated bounds on higgsino properties using recent experimental data and projects future detection limitations in minimal supersymmetry models.

Findings

Strong limits from LUX-ZEPLIN constrain gaugino masses.

Upper bounds on higgsino mass splittings are established.

Future experiments may face neutrino fog hindering detection.

Abstract

A higgsino could be some or all of the dark matter, with a mass bounded from above by about 1.1 TeV assuming a thermal freezeout density, and from below by collider searches. Direct detection experiments imply purity constraints on a dark matter higgsino, limiting the mixing with the electroweak gauginos. Using the new strong limits available as of the end of 2024 from the LUX-ZEPLIN experiment, I quantify the resulting lower bounds on gaugino masses and upper bounds on higgsino mass splittings, assuming that the scalar superpartners and Higgs bosons of minimal supersymmetry are in the decoupling limit. Similar bounds are projected for the critical future scenario that direct detection experiments reach the neutrino fog that hampers discovery prospects.