Charginos and Neutralinos in the Light of Radiative Corrections: Sealing the Fate of Higgsino Dark Matter

Abstract

We analyze the LEP constraints from searches for charginos $χ^{\pm}$ and neutralinos $χ_i$, taking into account radiative corrections to the relations between their masses and the underlying Higgs-mixing and gaugino-mass parameters $μ, m_{1/2}$ and the trilinear mass parameter $A_t$. Whilst radiative corrections do not alter the excluded domain in $m_{χ^{\pm}}$ as a function of $m_{χ^{\pm}} - m_χ$, its mapping into the $μ, m_{1/2}$ plane is altered. We update our previous lower limits on the mass of gaugino dark matter and on tan$β$, the ratio of Higgs vacuum expectation values, in the light of the latest LEP data and these radiative corrections. We also discuss the viability of Higgsino dark matter, incorporating co-annihilation effects into the calculation of the Higgsino relic abundance. We find that Higgsino dark matter is viable for only a very limited range of $μ$ and $m_{1/2}$, which will be explored completely by upcoming LEP runs.

Version to appear in Phys. Rev. D., 21 pages in LateX, including 10 encapsulated postscript figures; uses epsf.sty.; Figures modified (one deleted), conclusions unchanged