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

The neutralino-nucleon (χ⁰-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 χ⁰χ⁰ and Zχ⁰χ⁰ 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 σ_χ⁰N~10^-45 cm² or less.