Date of this Version
PHYSICAL REVIEW D 91, 075005 (2015)
In natural supersymmetry models, Higgsinos are always light because μ2 cannot be much larger than [?], while squarks and gluinos may be very heavy. Unless gluinos are discovered at LHC13, the commonly assumed unification of gaugino mass parameters will imply correspondingly heavy winos and binos, resulting in a Higgsino-like lightest supersymmetric particle (LSP) and small inter-Higgsino mass splittings. The small visible energy release in Higgsino decays makes their pair production difficult to detect at the LHC. Relaxing gaugino mass universality allows for relatively light winos and binos without violating LHC gluino mass bounds and without affecting naturalness. In the case where the bino mass M1 [?] μ, then one obtains a mixed bino-Higgsino LSP with instead sizable [?] - [?] and [?] - [?] mass gaps. The thermal neutralino abundance can match the measured dark matter density in contrast to models with aHiggsino-like LSP where weakly interacting massive particles are underproduced by factors of 10–15. If instead [?] [?] μ, then one obtains a mixed wino-Higgsino LSP with large [?] - [?] but small [?] - [?] mass gaps with still an underabundance of thermally produced weakly interacting massive particles. We discuss dark matter detection in other direct and indirect detection experiments and caution that the bounds from these must be interpreted with care. Finally, we show that LHC13 experiments should be able to probe these nonuniversal mass scenarios via a variety of channels including multilepton + [?] events, WZ + [?] events, Wh + [?] events, and W±W± + [?] events from electroweak chargino and neutralino production.