LHC Tests of Light Neutralino Dark Matter without Light Sfermions

TL;DR

This paper investigates the lower mass limits of lightest neutralino dark matter in the MSSM with heavy sfermions, using LHC data to set constraints that surpass some dark matter detection bounds.

Contribution

It introduces a simplified model focusing on key spectrum features and reinterprets LHC searches to derive new, more stringent limits on light neutralino masses in this scenario.

Findings

LHC data can impose stronger constraints than dark matter experiments.

Upper bounds on the Higgsino mass parameter are derived for neutralinos below 100 GeV.

Simplified models effectively connect collider results with dark matter properties.

Abstract

We address the question how light the lightest MSSM neutralino can be as dark matter candidate in a scenario where all supersymmetric scalar particles are heavy. The hypothesis that the neutralino accounts for the observed dark matter density sets strong requirements on the supersymmetric spectrum, thus providing an handle for collider tests. In particular for a lightest neutralino below 100 GeV the relic density constraint translates into an upper bound on the Higgsino mass parameter $\mu$ in case all supersymmetric scalar particles are heavy. One can define a simplified model that highlights only the necessary features of the spectrum and their observable consequences at the LHC. Reinterpreting recent searches at the LHC we derive limits on the mass of the lightest neutralino that, in many cases, prove to be more constraining than dark matter experiments themselves.