Direct detection of the Wino and Higgsino-like neutralino dark matter at one-loop level

Abstract

The neutralino-nucleon (${\stackrel{\texttildelow{}}{\ensuremath{\chi}}}^{0}$-$N$) scattering is an important process for direct dark matter searches. In this paper we discuss one-loop contributions to the cross section in the winolike and Higgsino-like LSP cases. The neutralino-nucleon scattering mediated by the Higgs ${\stackrel{\texttildelow{}}{\ensuremath{\chi}}}^{0}{\stackrel{\texttildelow{}}{\ensuremath{\chi}}}^{0}$ and $Z{\stackrel{\texttildelow{}}{\ensuremath{\chi}}}^{0}{\stackrel{\texttildelow{}}{\ensuremath{\chi}}}^{0}$ couplings at tree level is suppressed by the gaugino-Higgsino mixing at tree-level when the neutralino is close to a weak eigenstate. The one-loop contribution to the cross section, generated by the gauge interaction, is not suppressed by any SUSY particle mass or mixing in the wino- and Higgsino-like LSP cases. It may significantly alter the total cross section when ${\ensuremath{\sigma}}_{{\stackrel{\texttildelow{}}{\ensuremath{\chi}}}^{0}N}\ensuremath{\sim}{10}^{\ensuremath{-}45}\text{ }\text{ }{\mathrm{c}\mathrm{m}}^{2}$ or less.