Phenomenology of a Fluxed MSSM

TL;DR

This study analyzes a highly constrained flux-induced MSSM arising from Type IIB orientifold fluxes, where soft terms satisfy $M_{1/2}=M$, $A_0=-3M$, $m_0=|M|$, and $B=-2M$, with the supersymmetric parameter $\mu$ left as a separate input. Through RG running and radiative EWSB, the spectrum becomes a function of $M$ and reveals two viable $\tan\beta$ regions for $\mu<0$: a low-$\tan\beta$ branch around $3\!\le\!\tan\beta\!\le\!5$ and a high-$\tan\beta$ branch roughly $25\!\le\!\tan\beta\!\le\!40$, while $\mu>0$ is incompatible with consistent EWSB under these boundary conditions. A comprehensive phenomenological analysis applying $b\rightarrow s\gamma$, $\delta a_\mu$, LEP Higgs bounds, and WMAP relic density finds that the low-$\tan\beta$ branch favors $M\gtrsim 270$ GeV (and $M\gtrsim 550$ GeV from $m_h$), with the LSP being bino-like and DM cosmology generally disfavoring stability of the LSP in this regime. The high-$\tan\beta$ branch requires heavier spectra, with $M\gtrsim 750$ GeV from $\delta a_\mu$ and $M\gtrsim 1100$ GeV from $b\rightarrow s\gamma$, though it remains compatible with all constraints; a heavy-spectrum scenario around $M\approx 1100$ GeV yields the correct DM relic density, modestly alleviated by potential underlying relations such as $\mu=-2M$ that could reduce fine-tuning. Overall, the model makes sharp, testable predictions for sparticle masses and Higgs sectors, and highlights how a simple string-inspired boundary condition can yield distinct, falsifiable MSSM phenomenology.

Abstract

We analyze the phenomenology of a set of minimal supersymmetric standard model (MSSM) soft terms inspired by flux-induced supersymmetry (SUSY)-breaking in Type IIB string orientifolds. The scheme is extremely constrained with essentially only two free mass parameters: a parameter M, which sets the scale of soft terms, and the mu parameter. After imposing consistent radiative electro-weak symmetry breaking (EWSB) the model depends upon one mass parameter (say, M). In spite of being so constrained one finds consistency with EWSB conditions. We demonstrate that those conditions have two solutions for mu<0, and none for mu>0. The parameter tan beta results as a prediction and is approximately 3-5 for one solution, and 25-40 for the other, depending upon M and the top mass. We examine further constraints on the model coming from b->s gamma, the muon g-2, Higgs mass limits and WMAP constraints on dark matter. The MSSM spectrum is predicted in terms of the single free parameter M. The low tan beta branch is consistent with a relatively light spectrum although it is compatible with standard cosmology only if the lightest neutralino is unstable. The high tan beta branch is compatible with all phenomenological constraints, but has quite a heavy spectrum. We argue that the fine-tuning associated to this heavy spectrum would be substantially ameliorated if an additional relationship mu=-2M were present in the underlying theory.