THE SCALE WHERE SUPERSYMMETRY BREAKS: A NEW PARAMETER IN UNIFIED MODELS

Abstract
We examine supersymmetry breaking in string-inspired models through gaugino condensation in the hidden sector. With the physically sensible assumption that observable supersymmetry breaking effects turn off above the gaugino condensation scale (Λh), we derive a realistic range for the scale where supersymmetry breaks (1012 GeV<ΛSUSY= Λh16 GeV) which should be contrasted with the usual identification of ΛSUSY with the gauge coupling unification scale. We also derive constraints on the hidden sector to be consistent with this ΛSUSY range and to allow supersymmetry breaking with a perturbative gauge coupling in two-gaugino-condensate models. We then establish ΛSUSY as a new parameter in two unified models, the supersymmetric standard model (SSM), and the string-inspired standard model (SISM). We briefly review the two models, examining radiative electroweak breaking and the resulting phenomenology to determine allowed regions in parameter space as a function of ΛSUSY for a few representative cases. We also propose an algebraic combination of sparticle masses, which only depends on ΛSUSY, as a means of experimentally determining the scale at which supersymmetry breaks.