Model-Independent Assessment of Current Direct Searches for Spin-Dependent Dark Matter

I evaluate the current results of spin-dependent weakly interacting massive particle searches within a model-independent framework, showing the most restrictive limits to date derive from the combination of xenon and sodium iodide experiments. The extension of this analysis to the case of positive signal experiments is elaborated.

Figure 1

(a) ${\sigma }_p^{\mathrm{l}\mathrm{i}\mathrm{m}(A)}$ and (b) ${\sigma }_n^{\mathrm{l}\mathrm{i}\mathrm{m}(A)}$ vs $M_{\chi }$ for various elements by data from SIMPLE (thick solid), NAIAD (solid), CRESST (dotted), $\mathrm{D}\mathrm{A}\mathrm{M}\mathrm{A}/\mathrm{X}\mathrm{e}\mathrm{\text{−}}2$ (dash-dotted), DAMA/NaI (dotted for Na, dashed for I), and Tokyo (dashed).

Figure 2

Excluded regions in the $a_p\mathrm{\text{−}}{a}_n$ plane for $M_{\chi }=50\mathrm{G}\mathrm{e}\mathrm{V}/c^2$ , for the experiments of Table . The resulting allowed region is determined by the intersection of NAIAD and $\mathrm{D}\mathrm{A}\mathrm{M}\mathrm{A}/\mathrm{X}\mathrm{e}\mathrm{\text{−}}2$.

Figure 3

Permitted regions for a positive signal (elliptical shell), and two null signal (dashed and solid) experiments. The dotted inner lines are arbitrary and for illustrative purpose only. The two thick border areas are the intersection of current DAMA/NaI and $\mathrm{D}\mathrm{A}\mathrm{M}\mathrm{A}/\mathrm{X}\mathrm{e}\mathrm{\text{−}}2$ results; if also $\mathrm{D}\mathrm{A}\mathrm{M}\mathrm{A}/\mathrm{X}\mathrm{e}\mathrm{\text{−}}2$ had a positive signal this intersection would become the four hatched regions; a positive signal F-based experiment could reduce such intersection to the two solid regions (see text).