The Higgs Boson Mass as a Probe of the Minimal Supersymmetric Standard Model

Abstract

Recently, the LEP collaborations have reported a lower bound on a Standard Model-like Higgs boson of order 89 GeV. We discuss the implications of this bound for the minimal supersymmetric extension of the Standard Model (MSSM). In particular, we show that the lower bound on $\tanβ$, which can be obtained from the presently allowed Higgs boson mass value, becomes stronger than the one set by the requirement of perturbative consistency of the theory up to scales of order $M_{GUT}$ (associated with the infrared fixed-point solution of the top quark Yukawa coupling) in a large fraction of the allowed parameter space. The potentiality of future LEP2 searches to further probe the MSSM parameter space is also discussed.

Figures (5)

• Figure 1: Bounds on $\tan\beta$ obtained for $m_t^{pole}=175$ GeV and for a lower bound on the Higgs boson mass $M_h>88$ GeV, as a function of the heavier stop mass, for different values of the stop mass splitting $\Delta M_{\tilde{t}} = 0$--500 GeV (solid lines). Also plotted here are the top Yukawa coupling perturbativity bounds for the case of heavy gluino ($m_{\tilde{g}} = M_{\tilde{t}_2}$) for $\Delta M_{\tilde{t}} = 400$ GeV and $\sin2\theta_{\tilde{t}}=\pm1$ (upper-lower dashed lines), and for heavy gluino (center-dashed lines) and light gluino ($m_{\tilde{g}} = 200$ GeV) (dotted line) for $\Delta M_{\tilde{t}} = 0$.
• Figure 2: The same as Fig. 1, but for $m_t^{pole} = 170$ GeV and $m_t^{pole}= 180$ GeV.
• Figure 3: The same as Fig. 1, but for lower bounds on the Higgs boson mass of 96 GeV and 106 GeV.
• Figure 4: Bounds coming from the constraints on the parameter $(\Delta \rho)^{stops}$ (shadowed region) in the heavier stop mass--stop mixing angle plane, for values of $\tan\beta = 1.5$, and for different values of the lighter stop mass $M_{\tilde{t}_1} = 100$, 200 and 300 GeV. Also shown here are the bounds obtained from the present limit on the Higgs boson mass (regions between solid lines).
• Figure 5: The same as Fig. 1, but with five additional ${\bf 5}+{\bf \bar{5}}$ pairs (or equivalently, two ${\bf 5}+{\bf \bar{5}}$ pairs and one ${\bf 10}+{\bf \overline{10}}$ pair) added at the scale of 250 TeV.