The last refuge of mixed wino-Higgsino dark matter

Abstract

We delineate the allowed parameter and mass range for a wino-like dark matter particle containing some Higgsino admixture in the MSSM by analysing the constraints from diffuse gamma-rays from the dwarf spheroidal galaxies, galactic cosmic rays, direct detection and cosmic microwave background anisotropies. A complete calculation of the Sommerfeld effect for the mixed-neutralino case is performed. We find that the combination of direct and indirect searches poses significant restrictions on the thermally produced wino-Higgsino dark matter with correct relic density. For μ > 0 nearly the entire parameter space considered is excluded, while for μ < 0 a substantial region is still allowed, provided conservative assumptions on astrophysical uncertainties are adopted.