# How light a higgsino or a wino dark matter can become in a compressed scenario of MSSM

## TL;DR

This paper investigates how coannihilations with sleptons and squarks in the MSSM can significantly lower the viable mass range for Higgsino and Wino dark matter, affecting detection prospects and collider constraints.

## Contribution

It provides a detailed analysis of coannihilation effects in compressed MSSM scenarios, revealing extended mass ranges and detection implications for Higgsino and Wino dark matter.

## Key findings

- Coannihilations reduce the lower DM mass limit by over 50%.
- Squark-Higgsino degeneracy can extend the upper DM mass limit.
- Direct detection signals are significantly affected by squark exchange contributions.

## Abstract

Higgsinos and Wino have strong motivations for being Dark Matter (DM) candidates in supersymmetry, but their annihilation cross sections are quite large. For thermal generation and a single component DM setup the higgsinos or wino may have masses of around 1 or 2-3 TeV respectively. For such DM candidates, a small amount of slepton coannihilation may decrease the effective DM annihilation cross section. This, in turn reduces the lower limit of the relic density satisfied DM mass by more than 50%. Almost a similar degree of reduction of the same limit is also seen for squark coannihilations. However, on the contrary, for near degeneracy of squarks and higgsino DM, near its generic upper limit, the associated coannihilations may decrease the relic density, thus extending the upper limit towards higher DM masses. We also compute the direct and indirect detection signals. Here, because of the quasi-mass degeneracy of the squarks and the LSP, we come across a situation where squark exchange diagrams may contribute significantly or more strongly than the Higgs exchange contributions in the spin-independent direct detection cross section of DM. For the higgsino-DM scenario, we observe that a DM mass of 600 GeV to be consistent with WMAP/PLANCK and LUX data for sfermion coannihilations. The LUX data itself excludes the region of 450 to 600 GeV, by a half order of magnitude of the cross-section, well below the associated uncertainty. The similar combined lower limit for a wino DM is about 1.1 TeV. There is hardly any collider bound from the LHC for squarks and sleptons in such a compressed scenario where sfermion masses are close to the mass of a higgsino/wino LSP.