The higgsino-singlino sector of the NMSSM: Combined constraints from dark matter and the LHC

A light singlino is a promising candidate for dark matter, and a light higgsino is natural in the parameter space of the NMSSM. We study the combined constraints on this scenario resulting from the dark matter relic density, the most recent results from direct detection experiments, LEP and the LHC. In particular limits from a recent search for electroweak production of charginos and neutralinos at $\sqrt{s}=13$ TeV after 35.9 fb$^{-1}$ by CMS and constraints on spin-independent dark matter-nucleon cross sections from XENON1T after one tonne$\times$year exposure are considered. We find that scenarios with higgsino masses below $\sim 250$ GeV as well as singlino masses below $\sim 100$ GeV are strongly constrained depending, however, on assumptions on the bino mass parameter $M_1$. Benchmark points and branching fractions for future searches at the LHC are proposed.