TOWARDS A DYNAMICAL DETERMINATION OF PARAMETERS IN THE MINIMAL SUPERSYMMETRIC STANDARD MODEL

In the Minimal Supersymmetric Standard Model (MSSM), the scale M(SUSY) of soft supersymmetry breaking is usually assumed to be of the order of the electroweak scale. We reconsider here the possibility of treating M(SUSY) as a dynamical variable. Its expectation value should be determined by minimizing the vacuum energy, after including MSSM quantum corrections. We point out the crucial role of the cosmological term for a dynamical generation of the desired hierarchies m(z), M(SUSY) << M(P). Inspired by four-dimensional superstring models, we also consider the Yukawa couplings as dynamical variables. We find that the top Yukawa coupling is attracted close to its effective infrared fixed point, corresponding to a top-quark mass in the experimentally allowed range. As an illustrative example, we present the results of explicit calculations for a special case of the MSSM.