Soft SUSY breaking terms in stringy scenarios. Computation and phenomenological viability

Abstract

We calculate the soft SUSY breaking terms arising from a large class of string scenarios, namely symmetric orbifold constructions, and study its phenomenological viability. They exhibit a certain lack of universality, unlike the usual assumptions of the minimal supersymmetric standard model. Assuming gaugino condensation in the hidden sector as the source of SUSY breaking, it turns out that squark and slepton masses tend to be much larger than gaugino masses. Furthermore, we show that these soft breaking terms can be perfectly consistent with both experimental and naturalness constraints (the latter comes from the absence of fine tuning in the SU(2) × U(1) Y → U(1) em breaking process). This is certainly non-trivial and in fact imposes interesting constraints on measurable quantities. More precisely, we find that the gluino mass ( M 3) and the chargino mass ( M χ ±) cannot be much higher than their present experimental lower bounds ( M 3⪅285 GeV; M χ ± ⪅80 GeV), while squark and slepton masses must be much larger ( ⪆1 TeV ). This can be considered as an observational signature of this kind of stringy scenarius. Besides, the top mass is constrained to be within a range (80⪅ m t ⪅165 GeV) remarkably consistent with its present experimental bounds.