Light Higgsino Dark Matter in the MSSM on D-branes

Abstract

When supersymmetry breaking is dominated by the complex structure moduli and the universal dilaton, a subset of the supersymmetry parameter space in a realistic MSSM constructed from intersecting/magnetized D-branes are universal, similar to the effective mSUGRA/CMSSM parameter space with a universal scalar mass m_0, a universal gaugino mass $m_{1/2}$ and with the universal trilinear term fixed to be minus the gaugino mass, A_0=-m_{1/2}. More generally, the scalar mass-squared terms for sfermions are split about the Higgs mass-squared terms, m_{Q_L,L_L}^2=m_H^2 - Delta m^2 and m_{Q_R,L_R}^2=m_H^2 + \Delta m^2, for generic values of the Kahler moduli. The scalar masses are universal only for a specific choice of the Kahler moduli. The hyberbolic branch/focus point (HB/FP) regions of this parameter space are present for both Delta m^2 = 0$ and \Delta m^2 \ne 0. Interestingly, 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 EWFT between 3-7% may be obtained. The spin-independent direct-detection crosssections are in range of future experiments such as XENON-1T 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.