From LUX-ZEPLIN to Colliders: Probing Higgsino Dark Matter

Abstract

The high-energy nuclear recoil event with recoil energy $E_R \approx 248\text{ keV}$ observed by the LZ collaboration provides an exciting hint toward a model with a $1.1\text{ TeV}$ Higgsino inelastic dark matter. Such a recoil energy requires a mass splitting of order ($δ\approx 350\text{ keV}$) between the two nearly-degenerate neutral states. We show that within the framework of the MSSM, the model predicts a nearly-degenerate charged Higgsino state, chargino, whose mass splitting from the neutral states is of order $\mathcal{O}(350)$~MeV. The subsequent decays of such charginos once produced at colliders would lead to a sub-centimeter charged track or tracklet (with lifetime $τ\approx 0.025\text{ ns}$) at the detector. We show that such a scenario is not constrained by the current LHC bounds, and could be tested at future high-energy colliders, including HL-LHC, 100 TeV $pp$ colliders, and muon colliders. The most critical requirement is how short a track or tracklet can be reconstructed.