Light Neutralinos and WIMP direct searches

Abstract

The predictions of our previous analyses about possible low-mass (lower than 50 GeV) relic neutralinos are discussed in the light of the most recent results from WIMP direct detection experiments. It is proved that these light neutralinos are quite compatible with the new annual-modulation data of the DAMA Collaboration; our theoretical predictions are also compared with the upper bounds of the CDMS and EDELWEISS Collaborations.

Figures (2)

• Figure 1: Ratio of the $\tilde{H}_1^\circ$ content to the $\tilde{B}$ content in the neutralino composition as a function of the neutralino mass $m_\chi$. The upper branch of the solid line derives from neutralino diagonalization (see text), while the lower one is obtained from $\Omega_{\chi} h^2 \leq (\Omega_{CDM} h^2)_{\rm max}=0.131$.
• Figure 2: Scatter plot of $\xi \sigma_{\rm scalar}^{(\rm nucleon)}$ versus $m_{\chi}$. Crosses (red) and dots (blue) denote neutralino configurations with $\Omega_{\chi} h^2 \geq (\Omega_{CDM} h^2)_{\rm min}$ and $\Omega_{\chi} h^2 < (\Omega_{CDM} h^2)_{\rm min}$, respectively ($(\Omega_{CDM} h^2)_{\rm min}=0.095$) (a) The curves delimit the DAMA region where the likelihood-function values are distant more than $4 \sigma$ from the null (absence of modulation) hypothesis dama2; this region is the union of the regions obtained by varying the WIMP DF over the set considered in Ref. bcfs. (b) The solid and the dashed lines are the experimental upper bounds given by the CDMS cdms2 and the EDELWEISS edelweiss Collaborations, respectively, under the hypothesis that the WIMP DF is given by an isothermal distribution with a standard set of astrophysical parameters.