The Supersymmetric Parameter Space in Light of B-physics Observables and Electroweak Precision Data

TL;DR

The paper constrains supersymmetric parameter spaces by performing a combined χ^2 fit to EWPO and BPO within CMSSM and NUHM frameworks, enforcing the WMAP-derived cold dark matter density. It demonstrates a persistent preference for a relatively low SUSY-breaking scale in the CMSSM, with mild tension between EWPO and BPO, and shows that NUHM can achieve lower χ^2 in targeted (M_A, tanβ) regions, notably in the P2 plane (M_A≈340 GeV, tanβ≈35) where χ^2≈3.5. The analysis highlights that Mh is typically near the LEP limit, while light sparticles are favored and could be accessible at the LHC, with complementary prospects at the ILC. The work emphasizes the evolving role of precision measurements and dark matter constraints in shaping SUSY parameter-space in the near term.

Abstract

Indirect information about the possible scale of supersymmetry (SUSY) breaking is provided by B-physics observables (BPO) as well as electroweak precision observables (EWPO). We combine the constraints imposed by recent measurements of the BPO BR(b -> s gamma), BR(B_s -> mu^+ mu^-), BR(B_u -> tau nu_tau) and Delta M_{B_s} with those obtained from the experimental measurements of the EWPO M_W, sin^2 theta_eff, Gamma_Z, (g-2)_mu and M_h, incorporating the latest theoretical calculations of these observables within the Standard Model and supersymmetric extensions. We perform a chi^2 fit to the parameters of the constrained minimal supersymmetric extension of the Standard Model (CMSSM), in which the SUSY-breaking parameters are universal at the GUT scale, and the non-universal Higgs model (NUHM), in which this constraint is relaxed for the soft SUSY-breaking contributions to the Higgs masses. Assuming that the lightest supersymmetric particle (LSP) provides the cold dark matter density preferred by WMAP and other cosmological data, we scan over the remaining parameter space. Within the CMSSM, we confirm the preference found previously for a relatively low SUSY-breaking scale, though there is some slight tension between the EWPO and the BPO. In studies of some specific NUHM scenarios compatible with the cold dark matter constraint we investigate M_A-tan_beta planes and find preferred regions that have values of chi^2 somewhat lower than in the CMSSM.

Figures (21)

• Figure 1: The CMSSM predictions for $M_W$ are shown as functions of $m_{1/2}$ along the WMAP strips for (a) $\tan \beta = 10$ and (b) $\tan \beta = 50$ for various $A_0$ values. In each panel, the centre (solid) line is the present central experimental value, and the (solid) outer lines show the current $\pm 1$-$\sigma$ range. The dashed lines correspond to the full error including also parametric and intrinsic uncertainties.
• Figure 2: The CMSSM predictions for $\sin^2\theta_{\mathrm{eff}}$ as functions of $m_{1/2}$ along the WMAP strips for (a) $\tan \beta = 10$ and (b) $\tan \beta = 50$ for various $A_0$ values. In each panel, the centre (solid) line is the present central experimental value, and the (solid) outer lines show the current $\pm 1$-$\sigma$ range. The dashed lines correspond to the full error including also parametric and intrinsic uncertainties.
• Figure 3: The CMSSM predictions for $\Gamma_Z$ as functions of $m_{1/2}$ along the WMAP strips for (a) $\tan \beta = 10$ and (b) $\tan \beta = 50$ for various $A_0$ values. In each panel, the centre (solid) line is the present central experimental value, and the (solid) outer lines show the current $\pm 1$-$\sigma$ range. The dashed lines correspond to the full error including also parametric and intrinsic uncertainties.
• Figure 4: The CMSSM predictions for $(g-2)_\mu$, $\Delta a_\mu$, as functions of $m_{1/2}$ along the WMAP strips for (a) $\tan \beta = 10$ and (b) $\tan \beta = 50$ for various $A_0$ values. In each panel, the centre (solid) line is the present central experimental value, and the solid (dotted) outer lines show the current $\pm 1 (2)$-$\sigma$ ranges.
• Figure 5: The CMSSM predictions for $M_h$ as functions of $m_{1/2}$ with (a) $\tan \beta = 10$ and (b) $\tan \beta = 50$ for various $A_0$. We also show the present 95% C.L. exclusion limit of $114.4 \,\, \mathrm{GeV}$ and a hypothetical LHC measurement of $M_h = 116.4 \pm 0.2 \,\, \mathrm{GeV}$.