MSSM without a free parameter

TL;DR

This paper explores a minimal supersymmetric model with no free parameters, fixing gaugino and mu terms to match observed Higgs and Z boson masses, and finds viable parameter sets explaining dark matter and satisfying experimental constraints.

Contribution

It introduces a parameter-free MSSM scenario with fixed gaugino and mu terms, identifying new viable parameter sets consistent with Higgs mass and dark matter observations.

Findings

Three independent parameter sets identified, including novel ones.

Dark matter explained by non-thermal gravitino production from SUSY particle decays.

Model satisfies constraints from electric dipole moments and Big Bang Nucleosynthesis.

Abstract

It is often argued that the minimal supersymmetric standard model has O(100) free parameters and the generic parameter region is already excluded by the null observation of the flavor and CP violating processes as well as the constraints from the LHC experiments. This situation naturally leads us to consider the case where all the dangerous soft supersymmetry breaking terms such as the scalar masses and scalar couplings are absent, while only the unified gaugino mass term and the mu term are non-vanishing at the grand unification scale. We revisit this simple situation taking into account the observed Higgs boson mass, 125 GeV. Since the gaugino mass and the mu term are fixed in order to explain the Higgs boson and the Z boson masses, there is no free parameter left in this scenario. We find that there are three independent parameter sets exist including ones which have not been discussed in the literature. We also find that the abundance of the dark matter can be explained by relic gravitinos which are non-thermally produced as decay products of the SUSY particles while satisfying constraints from Big Bang Nucleosynthesis. We discuss the effects of the gravity mediation which generically give contribution to the soft terms of the order of the gravitino mass. It turns out that newly found parameter set is preferable to explain the Higgs boson mass as well as the gravitino dark matter while satisfying the constraints from the electric dipole moments of the electron and the nucleon.