Supersymmetry without a Light Higgs Boson

Abstract

Motivated by the absence, so far, of any direct signal of conventional low-energy supersymmetry, we explore the consequences of making the lightest Higgs boson in supersymmetry relatively heavy, up to about 300 GeV, in the most straightforward way, i.e. via the introduction of a chiral singlet S with a superpotential interaction with the Higgs doublets, λS H_1 H_2. The coupling λdominates over all the other couplings and, to maintain the successful perturbative analysis of the ElectroWeak Precision Tests, is only restricted to remain perturbative up to about 10 TeV. The general features of this "λSUSY" framework, which deviates significantly from the MSSM or the standard NMSSM, are analyzed in different areas: ElectroWeak Precision Tests, Dark Matter, naturalness bounds on superparticle masses, and LHC signals. There is a rich Higgs/Higgsino sector in the (200-700)GeV mass region, which may include LSP Higgsino dark matter. All other superpartners, apart from the top squarks, may naturally be heavier than 1-2 TeV. This picture can be made consistent with gauge coupling unification.

Figures (9)

• Figure 1: The black (darker) curve shows the SM results with a Higgs mass $m_{h} = 100-350~{\rm GeV}$ in $50~{\rm GeV}$ increments. The ellipses show the regions of the $S$-$T$ plane allowed by EWPT at $1\sigma$ and $2\sigma$. The red (lighter) curves give the predictions from the Higgs scalar sector in $\lambda$SUSY, as described in the text, with values of $\tan\beta$ in the interval $\tan\beta = 1\!\sim\!5$ as indicated and $m_{H^{\pm}}=350,500,700~{\rm GeV}$.
• Figure 2: The expected stop-sbottom contribution to the $T$ parameter is constrained by naturalness to lie above the curve.
• Figure 3: The contributions from the Higgsinos to the $T$ parameter (red color; contour values not framed) and the $S$ parameter (blue color; contour values framed). Vertical dashed lines represent an upper limit on $\mu$ coming from naturalness. Shaded regions indicate the regions in which the lightest neutralino is lighter than $m_Z/2 \simeq 45~{\rm GeV}$.
• Figure 4: The lightest neutralino relic density $\Omega_{\chi} h^{2}$ for four values of $\tan\beta$. The contours for $\Omega_{\chi} h^{2} = 0.01, 0.05$ and $0.2$ are denoted by the blue (thin solid) lines, while the blue (darkest) shading indicates regions with $0.09 \mathrel{\hbox{$<$$\sim$}} \Omega_{\chi} h^{2} \mathrel{\hbox{$<$$\sim$}} 0.13$, corresponding to the $95\%$CL region from WMAP Spergel:2003cb. Gray shading indicates regions where $m_{\chi} < m_{Z}/2$. The contours for the mass of the LSP, $m_\chi = 80, 150$ and $200~{\rm GeV}$, are also superimposed by dashed lines.
• Figure 5: Dark matter detection cross section $\sigma_{h}$ in units of $10^{-44}~{\rm cm}^2$ (i.e. the factor $G$ in the text) in the $\mu$-$M$ plane for $\tan\beta = 1.3, 1.5$ and $m_{H^\pm} = 400, 700~{\rm GeV}$. The blue (darkest) regions indicate the regions for $0.09 \mathrel{\hbox{$<$$\sim$}} \Omega_{\chi} h^{2} \mathrel{\hbox{$<$$\sim$}} 0.13$ (see Fig. \ref{['fig:DM_plot']}), while the gray shaded regions indicate the ones where $m_{\chi} < m_{Z}/2$.