A 119-125 GeV Higgs from a string derived slice of the CMSSM

TL;DR

This paper presents a string-theory motivated slice of the CMSSM, where modulus-dominated SUSY breaking in Type IIB orientifolds enforces relations among soft terms that lead to $A=-2m$ and large $\tan\beta$. Imposing radiative EW symmetry breaking and viable neutralino dark matter leaves effectively a single scale parameter $M$ (plus a small flux correction $\rho_H$), predicting a Higgs mass in the $119$–$125$ GeV range and a heavy yet testable sparticle spectrum with stau coannihilation. The authors assess LHC detectability across 7–14 TeV runs, finding that early runs could probe parts of the parameter space while 14 TeV with sufficient luminosity would cover the full region; the model also yields a potentially long-lived stau with cosmological implications for BBN. They discuss fine-tuning and argue that anthropic considerations in a landscape could favor $m_h$ near 125 GeV, tying phenomenology to environmental selection while preserving testable collider predictions.

Abstract

The recent experimental hints for a relatively heavy Higgs with a mass in the range 119-125 GeV favour supersymmetric scenarios with a large mixing in the stop mass matrix. It has been shown that this is possible in the constrained Minimal Supersymmetric Standard Model (CMSSM), but only for a very specific relation between the trilinear parameter and the soft scalar mass, favouring A ~ -2m for a relatively light spectrum, and sizable values of tan(beta). We describe here a string-derived scheme in which the first condition is automatic and the second arises as a consequence of imposing radiative EW symmetry breaking and viable neutralino dark matter in agreement with WMAP constraints. More specifically, we consider modulus dominated SUSY-breaking in Type II string compactifications and show that it leads to a very predictive CMSSM-like scheme, with small departures due to background fluxes. Imposing the above constraints leaves only one free parameter, which corresponds to an overall scale. We show that in this construction $A=-3\sqrt{2}m\approx -2m$ and in the allowed parameter space tan(beta)=38-41, leading to 119 GeV < m_h < 125 GeV. We determine the detectability of this model and show that it could start being probed by the LHC at 7(8) TeV with a luminosity of 5(2) fb^-1, and the whole parameter space would be accessible for 14 TeV and 25 fb^-1. Furthermore, this scenario can host a long-lived stau with the right properties to lead to catalyzed BBN. We finally argue that anthropic arguments could favour the highest value for the Higgs mass that is compatible with neutralino dark matter, i.e., m_h~125 GeV.

Figures (14)

• Figure 1: General structure of a local F-theory $SU(5)$ GUT. The GUT group lives on 7-branes whose 4 extra dimensions beyond Minkowski wrap a 4-cycle $S$. This $S$ manifold is inside a 3 complex dimensional manifold $B_3$ where the 6 extra dimensions are compactified. The gauge bosons live in the bulk of $S$ whereas quarks, leptons, and Higgsses are localized in complex curves inside $S$. These matter curves ($10$ and ${\bar{5}}$ in the figure) correspond to the intersection of the 7-branes wrapping $S$ with other $U(1)$ 7-branes (not depicted in the figure). There is one matter curve for each $SU(5)$ rep. and at the intersection of matter curves with Higgs curves $H_u, H_d$ Yukawa couplings develop (figure taken from Ref. book).
• Figure 2: Pictorial view of the modulus dominance constrained MSSM as a slice of the Higgs non-universal HNUMSSM which is a slight deformation (due to the small flux parameter) of the CMSSM.
• Figure 3: Left) Trajectory in the $(M,\tan\beta)$ plane for which the REWSB conditions are fulfilled and the correct amount of dark matter is obtained. Right) Corresponding values of the flux, $\rho_H$. In both cases, dots correspond to points fulfilling the central value in WMAP result for the neutralino relic density. The dot-dashed line denotes points along which the matter density is critical, $\Omega_{matter}=1$, whereas the solid line indicates the points for which the stau becomes the LSP. The points below the dashed line are excluded by the lower bound on BR$(b\to s\gamma)$ and the upper bound on BR$(B_s\to\mu^+\mu^-)$ from Ref. cmslhcb and the recent LHCb result Aaij:2012ac. The gray area indicates the points compatible with the latter constraint when the $2\sigma$ error associated to the SM prediction is included.
• Figure 4: Universal gaugino mass versus the theoretical prediction for BR$(B_s\to\mu^+\mu^-)$. The dashed lines denote the experimental upper bound on this observable from Ref. cmslhcb and the recent LHCb result Aaij:2012ac. The $2,\sigma$ theoretical error on the SM prediction is indicated by means of a shaded region in both cases.
• Figure 5: Universal gaugino mass as a function of the resulting Higgsino mass parameter, $\mu$ at the unification scale for those points where both REWSB and viable neutralino dark matter are obtained.