Challenges for MSSM Higgs searches at Hadron Colliders

TL;DR

This paper investigates how B-physics constraints within a minimal flavor violating MSSM shape Higgs searches at hadron colliders. It combines MFV MSSM Higgs-sector phenomenology with collider projections from ATLAS/CMS and Tevatron, and analyzes four key observables $BR(B_s \to \mu^+ \mu^-)$, $\Delta M_s$, $BR(b \to s \gamma)$, and $BR(B_u \to \tau \nu)$ across benchmark scenarios, highlighting the dependence on $M_A$, $\tan\beta$, $\mu$, and $X_t$. The main finding is that large stop mixing $X_t$ with small $\mu$ is strongly constrained by B-physics, suppressing non-standard Higgs searches, while large $\mu$ and small $X_t$ relax these bounds and enhance $A/H \to \tau^+\tau^-$ reach; nonetheless, the LHC is predicted to probe the full MSSM parameter space for the SM-like Higgs with $30\,\text{fb}^{-1}$, whereas non-standard Higgs discovery remains contingent on $M_A$ and $\tan\beta$. The results map out a clear complementarity between flavor and collider searches, guiding strategies for Higgs discovery and parameter-space interpretation in MFV MSSM scenarios.

Abstract

In this article we analyze the impact of B-physics and Higgs physics at LEP on standard and non-standard Higgs bosons searches at the Tevatron and the LHC, within the framework of minimal flavor violating supersymmetric models. The B-physics constraints we consider come from the experimental measurements of the rare B-decays b -> s gamma and B_u -> tau nu and the experimental limit on the B_s -> mu+ mu- branching ratio. We show that these constraints are severe for large values of the trilinear soft breaking parameter A_t, rendering the non-standard Higgs searches at hadron colliders less promising. On the contrary these bounds are relaxed for small values of A_t and large values of the Higgsino mass parameter mu, enhancing the prospects for the direct detection of non-standard Higgs bosons at both colliders. We also consider the available ATLAS and CMS projected sensitivities in the standard model Higgs search channels, and we discuss the LHC's ability in probing the whole MSSM parameter space. In addition we also consider the expected Tevatron collider sensitivities in the standard model Higgs h -> b bbar channel to show that it may be able to find 3 sigma evidence in the B-physics allowed regions for small or moderate values of the stop mixing parameter.

Figures (5)

• Figure 1: The green(grey) hatched area is the 2$\sigma$ allowed region of the ratio $R_{B\tau \nu}$ if the fitted value of $|V_{ub}|$ is used to calculate the standard model prediction of the $B_u \to \tau \nu$ decay rate. The yellow(light grey) is corresponding region if the inclusive determination of $|V_{ub}|$ is used instead of the fitted value. The solid (dashed) lines show the variation of $R_{B\tau \nu}$ with respect to $\tan \beta$ for $M_A=150{\rm GeV}(250{\rm GeV})$, while the red (grey) color and blue (dark grey) color correspond to $X_t=0$ and $X_t=1$ TeV respectively.
• Figure 2: The red (grey) region, in all four figures, is excluded by the CDF experiment's search for non-standard Higgs bosons in the inclusive $A \to \tau^+ \tau^-$ channel at 1 fb$^{-1}$ luminosity. The dotted line shows the corresponding D0 excluded region at 1 fb$^{-1}$. (a) The solid and dashed lines represent the future reach for the Tevatron (at 4 fb$^{-1}$)and LHC (at 10 fb$^{-1}$ for $B_s \to \mu^+ \mu^-$ and at 30 fb$^{-1}$ for $A \to \tau^+ \tau^-$) respectively, where the red (dark gray) lines correspond to the non-standard Higgs search reaches in the $H\rightarrow \tau \tau$ channel while the black lines are the projected $\mathcal{BR}(B_s\rightarrow \mu^+ \mu^-)$ bounds for $\mu = -100$ GeV, $X_t = 2.4$ TeV, $M_{SUSY} = 1$ TeV and $M_3 = 0.8$ TeV. The green (gray) hatched regions are those allowed by the present B-physics constraints on the $B_u \to \tau \nu$$b \rightarrow s \gamma$ and $B_s \to \mu^+ \mu^-$ branching ratios. (b) and (c) For the same SUSY mass parameters the yellow (light gray) area is the 5$\sigma$ discovery region in the $h \rightarrow \gamma \gamma$ channel, while the green (gray) hatched area is the same for the $h \to \tau \tau$ channel for the CMS and ATLAS experiments respectively at 30 fb$^{-1}$. (d) Green (gray) hatched region is the 3$\sigma$ evidence region for the SM-like Higgs searches (at 4 fb$^{-1}$) at the Tevatron. (b)--(d) The areas surrounded by the dashed black curves correspond to the regions allowed by present B-physics constraints.
• Figure 3: (a)--(d) The lines and the colors correspond to the same quantities as in Fig. (\ref{['xt24mu1n:fig']}), where the SUSY parameters are the same except for $X_t = 1$ TeV.
• Figure 4: (a)--(d) The lines and the colors correspond to the same quantities as in Fig. (\ref{['xt24mu1n:fig']}), where the SUSY parameters are the same except for $X_t = 0$ GeV, $\mu = 1.5 \; M_{SUSY}$ and $M_{SUSY} = 2$ TeV. The region below the blue (black) solid line corresponds to the area excluded by the LEP bound on the SM-like Higgs boson for $m_t = 170.9$ GeV.
• Figure 5: (a)--(d) The lines and the colors correspond to the same quantities as in Fig. (\ref{['xt24mu1n:fig']}), where the SUSY parameters are the same except for $M_3 = 500$ GeV, $M_{SUSY} = 800$ GeV, $X_t = -1.2$ TeV and $\mu = 2.5$ TeV.