Status and prospects of light bino-higgsino dark matter in natural SUSY

Abstract

Given the recent progress in dark matter direction detection experiments, we examine a light bino-higgsino dark matter (DM) scenario ($M_1<100$ GeV and $\mu <300$ GeV) in natural supersymmetry with the electroweak fine tuning measure ${\Delta }_{EW}<30$. By imposing various constraints, we note that: (i) For $sign(\mu /M_1)=+1$, the parameter space allowed by the DM relic density and collider bounds can almost be excluded by the very recent spin-independent (SI) scattering cross section limits from the XENON1T (2017) experiment. (ii) For $sign(\mu /M_1)=-1$, the SI limits can be evaded due to the cancelation effects in the $h{\tilde{\chi }}_1^0{\tilde{\chi }}_1^0$ coupling, while rather stringent constraints come from the PandaX-II (2016) spin-dependent (SD) scattering cross section limits, which can exclude the higgsino mass $|\mu |$ and the LSP mass $m_{{\tilde{\chi }}_1^0}$ up to about 230 GeV and 37 GeV, respectively. Furthermore, the surviving parameter space will be fully covered by the projected XENON1T experiment or the future trilepton searches at the HL-LHC.

Comments: 15 pages, 4 figures, discussions and references added, accepted by EPJC