Neutralino-Nucleus Elastic Scattering in the MSSM with Explicit CP Violation

Abstract

We re-investigate the neutralino-nucleus elastic scattering as a promising dark matter detection mechanism including contributions from the scalar-pseudoscalar mixing of neutral Higgs states and the induced phase between two Higgs doublets due to the CP-violating phases of the scalar top and bottom sectors in the minimal supersymmetric standard model. The spin-dependent part of the cross section turns out to be hardly affected by the CP-violating induced phase due to a mutually destructive unavoidable suppression mechanism of various relevant supersymmetric parameters. On the other hand, although the phase $Φ_μ$ of the higgsino mass parameter is set to be zero, the spin-independent part, which can dominate over the spin-dependent part for heavy nuclei, can be strongly dependent on the CP-violating scalar-pseudoscalar mixing and the induced phase, in particular, for a large $|μ|$, a small charged Higgs boson mass, and a large trilinear term $|A|$ compared to the SUSY breaking scale. For a small $\tanβ$ and a large $|μ|$, the spin-independent cross section is enhanced by an order of magnitude as the phase $Φ_A$ of the trilinear term increases up to $π$, while for a large $\tanβ$ and a large $|μ|$ the spin-independent cross section is significantly suppressed for non-zero values of the phase $Φ_A$.