Light Higgsino dark matter in the MSSM on D-branes

Abstract

When supersymmetry (SUSY) breaking is dominated by the complex structure moduli and the universal dilaton, a subset of the SUSY parameter space in a realistic minimal supersymmetric standard model constructed from intersecting/magnetized D-branes are universal, similar to the effective minimal supergravity (mSUGRA)/constrained minimal supersymmetric standard model (CMSSM) parameter space with a universal scalar mass m0, a universal gaugino mass and with the universal trilinear term fixed to be minus the gaugino mass, A0 = −m1/2. More generally, the scalar mass-squared terms for sfermions are split about the Higgs mass-squared terms, and , for generic values of the Kähler moduli. The scalar masses are universal only for a specific choice of the Kähler moduli. The hyperbolic branch/focus point (HB/FP) regions of this parameter space are present for both and . Interestingly, it is known that FPs may be realized with any boundary condition of the form with x an arbitrary constant, the same form as those in this model. Thus, we should expect to obtain the same set of FPs in the model regardless of the choice of Kähler moduli. It should be emphasized that the more general choice of Kähler moduli goes beyond (mSUGRA/CMSSM). It is shown that there exists superpartner spectra with a light Higgsino-like LSP with 230–350 GeV and a Higgs mass in the range 124–126 GeV, and which satisfy most standard experimental constraints. Consequently, viable spectra with low electroweak fine-tuning between 3%–7% may be obtained. The spin-independent direct-detection crosssections are in range of future experiments such as XENON−1 T and super CDMS, while the relic density is smaller than the WMAP and Planck bounds by roughly a factor of ten, implying that the LSP is sub-dominant component of dark matter. In addition, most of the spectra are consistent with constraints from indirect-detection experiments.