Higgsino

In particle physics, a Higgsino, symbol
H͂
, is the theoretical superpartner of the Higgs boson, as predicted by supersymmetry. The Higgsino is a Dirac fermion and that is a weak isodoublet with hypercharge half under the Standard Model gauge symmetries. After electroweak symmetry breaking the Higgsino becomes a pair of neutral Majorana fermions called neutralinos and a charged Dirac fermion called a chargino (plus and minus). These states finally mix with the neutralinos (photino and zino) and chargino (charged wino plus and minus) to form the predicted particles which are four neutralinos and two charginos (plus and minus each). Such a linear combination of the Higgsino, bino and wino makes up the lightest supersymmetric particle (LSP), which is a particle physics candidate for the dark matter of the universe. In order to be such a candidate, it must be neutral (i.e. a neutralino rather than chargino).

In natural scenarios of SUSY, top squarks, bottom squarks, gluinos, and higgsino-enriched neutralinos and charginos are expected to be relatively light, enhancing their production cross sections. Higgsino searches have been performed by both the ATLAS and CMS experiments at the Large Hadron Collider at CERN, where physicists have searched for the direct electroweak pair production of Higgsinos. As of March 2014, no experimental evidence for Higgsinos has been reported.