On the Correlation Between the Spin-Independent and Spin-Dependent Direct Detection of Dark Matter

We study the correlation between spin-independent and spin-dependent scattering in the context of MSSM neutralino dark matter for both thermal and non-thermal histories. We explore the generality of this relationship with reference to other models. We discuss why either fine-tuning or numerical coincidences are necessary for the correlation to break down. We derive upper bounds on spin-dependent scattering mediated by a Z boson.