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

The neutralino-nucleon (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 chi(0)chi(0) and Zchi(0)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 sigma(chi)(0)Nsimilar to10(-45) cm(2) or less.