New contributions to neutralino elastic cross sections fromCPviolating phases in the minimal supersymmetric standard model

We compute the four-Fermi neutralino-quark interaction Lagrangian including contributions from the CP-violating phases in the MSSM. We find that neutralino-nucleus scattering cross sections relevant for direct detection experiments show a strong dependence on the value of the CP-violating phase associated with the μ parameter ${\theta }_{\mu }.$ In some cases, for a broad range of non-zero ${\theta }_{\mu },$ there are cancellations in the cross sections which reduce the cross section by more than an order of magnitude. In other cases, there may be enhancements as one varies ${\theta }_{\mu }.$