Probing LZ-Motivated TeV Higgsino Dark Matter through Heavier Sparticles at LHC

Abstract

The nearly pure TeV-scale Higgsino dark matter provides a natural explanation for the high-energy nuclear-recoil excess reported by LUX-ZEPLIN. Such a heavy and compressed Higgsino spectrum makes direct searches at the LHC challenging. We therefore investigate complementary probes through the production and decay of heavier sparticles. We perform a comprehensive analysis and obtain the following observations: (i) For a TeV Higgsino, the current LHC Run-2 searches exclude gluino up to approximately 2.2~TeV, while the HL-LHC can give an exclusion reach of 2.5--2.6~TeV and a discovery reach of 2.3--2.4~TeV; (ii) The light-flavor squark coannihilation window lies beyond the Run-2 reach, but its lower end could be excluded at the HL-LHC under optimistic assumptions; (iii) The Run-2 search does not exclude the stop or sbottom benchmarks; (iv) The slepton and heavier-electroweakino productions are too small to access at the HL-LHC.