WMAP Constraints, SUSY Dark Matter and Implications for the Direct Detection of SUSY

TL;DR

WMAP measurements tightly constrain neutralino dark matter in mSUGRA, including the hyperbolic branch of radiative electroweak symmetry breaking. Relic density can be achieved in both the conventional coannihilation region and the HB inversion region, though collider accessibility is region-dependent, with heavy sfermions and small mass splittings in the inversion zone posing challenges. Direct detection prospects remain viable, as the spin-independent neutralino–proton cross section falls within reach of next‑generation experiments, while the spin-dependent cross section is comparatively larger; the viability of the HB inversion region is sensitive to the hadronic corrections in gμ−2. The results highlight the complementary roles of cosmology, direct detection, and collider searches in probing the HB/FP landscape of SUSY and emphasize the need for improved hadronic inputs to sharpen constraints.

Abstract

Recently, WMAP has measured the cosmological parameters to a much greater accuracy. We analyze the implications of this more precise measurement for supersymmetric dark matter and for the direct detection of supersymmetry at accelerators. We consider mSUGRA including also the hyperbolic branch in the radiative breaking of the electroweak symmetry. On the part of the hyperbolic branch where the lightest neutralino is dominantly a higgsino rather than being mostly a bino, the relic density constraints are satisfied by coannihilation with the next lightest neutralino and the light chargino. Including this branch the lightest neutralino mass satisfies $m_{χ_1^0}\leq 1200$ GeV for $\tanβ\leq 50$. Constraints of $b\to s+γ$ and of $g_μ-2$ are also analyzed. It is shown that the neutralino-proton cross section in each case will fall within the reach of dark matter experiments. Possibility for the direct detection of supersymmetry is discussed in the allowed regions of the parameter space consistent with WMAP constraints. A brief discussion of the hyperbolic branch and focus point region (HB/FP) is also given.

Figures (7)

• Figure 1: Relic density constraint and neutralino mass range for $\tan\beta=10$
• Figure 2: Relic density constraint and neutralino mass range for $\tan\beta=30$
• Figure 3: Relic density constraint and neutralino mass range for $\tan\beta=50$
• Figure 4: A plot of the $B(B^0_s\rightarrow \mu^+\mu^-)$ constraint in the $m_{\frac{1}{2}}-m_0$ plane.
• Figure 5: Spin Independent and Spin Dependent Cross Sections for $\tan\beta=10$