Inparticle physics,for models withN= 1 supersymmetry ahiggsino,symbol H͂ ,is thesuperpartnerof theHiggs field.A higgsino is aDirac fermionicfield with spin1/2and it refers to aweak isodoubletwith hypercharge half under the Standard Model gauge symmetries. Afterelectroweak symmetry breakinghiggsino fields linearly mix with U(1) and SU(2) gauginos leading to fourneutralinosand twocharginos[1]that refer to physical particles. While the two charginos are charged Dirac fermions (plus and minus each), the neutralinos are electrically neutralMajorana fermions.In anR-parity-conserving version of theMinimal Supersymmetric Standard Model,the lightest neutralino typically becomes thelightest supersymmetric particle(LSP). The LSP is a particle physics candidate for thedark matterof the universe since it cannot decay to particles with lighter mass. A neutralino LSP, depending on its composition can be bino, wino or higgsino dominated in nature[2]and can have different zones of mass values in order to satisfy the estimated dark matter relic density. Commonly, a higgsino dominated LSP is often referred as a higgsino, in spite of the fact that a higgsino is not a physical state in the true sense.
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 theATLASandCMSexperiments at theLarge Hadron CollideratCERN,where physicists have searched for the direct electroweak pair production of Higgsinos. As of 2017, no experimental evidence for Higgsinos has been reported.[3][4]
If dark matter is composed only of Higgsinos, then the Higgsino mass is 1.1TeV.On the other hand, if dark matter has multiple components, then the Higgsino mass depends on the relevant multiverse distribution functions, making the mass of the Higgsino lighter.
