Enhancing Direct Detection of Higgsino Dark Matter

TL;DR

This paper explores enhanced detection methods for Higgsino dark matter, proposing new experimental setups and astrophysical considerations to improve sensitivity in identifying this elusive particle.

Contribution

It introduces a novel detection strategy involving large heavy-element volumes and astrophysical effects to better detect Higgsino dark matter.

Findings

Enhanced detector sensitivity with heavy element shielding.

Astrophysical factors like the LMC boost detection prospects.

Potential to cover much of the remaining Higgsino parameter space.

Abstract

While much supersymmetric weakly interacting massive particle (WIMP) parameter space has been ruled out, one remaining important candidate is Higgsino dark matter. The Higgsino can naturally realize the "inelastic dark matter" scenario, where the scattering off a nucleus occurs between two nearly-degenerate states, making it invisible to WIMP direct detection experiments if the splitting is too large to be excited. It was realized that a "luminous dark matter" detection process, where the Higgsino upscatters in the Earth and subsequently decays into a photon in a large neutrino detector, offers the best sensitivity to such a scenario. We consider the possibility of adding a large volume of a heavy element, such as Pb or U, around the detector. We also consider the presence of U and Th in the Earth itself, and the effect of an enhanced high-velocity tail of the dark matter distribution due to the presence of the Large Magellanic Cloud. These effects can significantly improve the sensitivity of detectors such as JUNO, SNO+, KamLAND, and Borexino, potentially making it possible in the future to cover much of the remaining parameter space for this classic supersymmetric WIMP dark matter.