Update on the Direct Detection of Supersymmetric Dark Matter

TL;DR

This work reassesses direct-detection prospects for supersymmetric dark matter by incorporating a potentially larger $\Sigma$ term and the updated top-quark mass, assessing their impact on spin-independent neutralino-nucleon scattering within CMSSM and beyond. The authors compute the cross sections from a detailed hadronic and SUSY framework, including hadronic uncertainties and WMAP relic-density constraints, and compare to CDMS II limits. They find that CMSSM benchmarks remain largely viable, while some non-universal scalar-mass models (LEEST/NUHM) are partially excluded, particularly for light neutralinos ($m_{\chi} \lesssim 700$ GeV) with large $\Sigma$. The results imply that current CDMS II sensitivity is just beginning to probe relevant SUSY parameter space, with future improvements of up to several orders of magnitude required to comprehensively test these models.

Abstract

We compare updated predictions for the elastic scattering of supersymmetric neutralino dark matter with the improved experimental upper limit recently published by CDMS II. We take into account the possibility that the π-nucleon Σterm may be somewhat larger than was previously considered plausible, as may be supported by the masses of exotic baryons reported recently. We also incorporate the new central value of m_t, which affects indirectly constraints on the supersymmetric parameter space, for example via calculations of the relic density. Even if a large value of Σis assumed, the CDMS II data currently exclude only small parts of the parameter space in the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking Higgs, squark and slepton masses. None of the previously-proposed CMSSM benchmark scenarios is excluded for any value of Σ, and the CDMS II data do not impinge on the domains of the CMSSM parameter space favoured at the 90 % confidence level in a recent likelihood analysis. However, some models with non-universal Higgs, squark and slepton masses and neutralino masses \lappeq 700 GeV are excluded by the CDMS II data.

Figures (8)

• Figure 1: The dependences on the $\pi$-nucleon $\Sigma$ term of the elastic cross sections of the benchmark points Bench2. The dashed lines indicate the sensitivities to $\sigma_0$ in the cases of benchmark scenarios C, G and J. The predicted cross sections are smaller than the CDMS II upper limits CDMS2 for the the models considered, for all $\Sigma$ values shown.
• Figure 2: The $(m_{1/2}, m_0)$ planes in the CMSSM for (a) $\tan \beta = 10, \ \mu < 0$, (b) $\tan \beta = 10, \ \mu > 0$, (c) $\tan \beta = 40, \ \mu < 0$ and (d) $\tan \beta = 57, \ \mu > 0$, all assuming $A_0 = 0$. We display the WMAP relic-density constraint, the experimental constraints due to $m_h$, $m_{\chi^\pm}$, $b \to s \gamma$ and $g_\mu - 2$, and contours of the spin-independent elastic-scattering cross section calculated for $\Sigma = 45$ and $64$ MeV (lighter, blue and black dotted contours, respectively), labelled by their exponents in units of picobarns.
• Figure 3: Scatter plots of the spin-independent elastic-scattering cross section predicted in the CMSSM for (a, b) $\mu < 0$ and (c, d) $\mu > 0$, with (a, c) $\Sigma = 45$ MeV and (b, d) $\Sigma = 64$ MeV.
• Figure 4: Scatter plots of the spin-independent elastic-scattering cross section predicted in the CMSSM for (a, b) $\tan \beta = 10, \mu > 0$ and (c, d) $\tan \beta = 50, \mu > 0$, with (a, c) $\Sigma = 45$ MeV and (b, d) $\Sigma = 64$ MeV. The predictions for models allowed at the 68% (90%) confidence levels are shown by blue $\times$ signs (green $+$ signs).
• Figure 5: As in Fig. \ref{['fig:CMSSM']}, but now for the LEEST.