Charginos and neutralinos in the light of radiative corrections: Sealing the fate of Higgsino dark matter

Abstract

We analyze the CERN LEP constraints from searches for charginos ${\ensuremath{\chi}}^{\ifmmode\pm\else\textpm\fi{}}$ and neutralinos ${\ensuremath{\chi}}_{i},$ taking into account radiative corrections to the relations between their masses and the underlying Higgs-mixing and gaugino-mass parameters \ensuremath{\mu}, ${m}_{1/2},$ and the trilinear mass parameter ${A}_{t}.$ While radiative corrections do not alter the excluded domain in ${m}_{{\ensuremath{\chi}}^{\ifmmode\pm\else\textpm\fi{}}}$ as a function of ${m}_{{\ensuremath{\chi}}^{\ifmmode\pm\else\textpm\fi{}}}\ensuremath{-}{m}_{\ensuremath{\chi}},$ its mapping into the \ensuremath{\mu}, ${m}_{1/2}$ plane is altered. We update our previous lower limits on the mass of gaugino dark matter and on $\mathrm{tan}\ensuremath{\beta},$ the ratio of Higgs vacuum expectation values, in light of the latest LEP data and these radiative corrections. We also discuss the viability of Higgsino dark matter, incorporating coannihilation effects into the calculation of the Higgsino relic abundance. We find that Higgsino dark matter is viable for only a very limited range of \ensuremath{\mu} and ${m}_{1/2},$ which will be explored completely by upcoming LEP runs.