BOTTOM-UP APPROACH AND SUPERSYMMETRY BREAKING

We present a bottom-up approach to the question of supersymmetry break ing in the MSSM. Starting with the experimentally measurable low-energ y supersymmetry-breaking parameters, which can take any values consist ent with present experimental constraints, we evolve them up to an arb itrary high energy scale. Approximate analytical expressions for such an evolution, valid for low and moderate values of tan beta, are prese nted. We then discuss qualitative properties of the high-energy parame ter space and, in particular, identify the conditions on the low-energ y spectrum that are necessary for the parameters at the high-energy sc ale to satisfy simple regular pattern such as universality or partial universality. As an illustrative example, we take low-energy parameter s for which light sparticles, within the reach of the LEP2 collider, a ppear in the spectrum, and which do not affect the Standard Model agre ement with the precision measurement data. Comparison between supersym metry breaking at the GUT scale and at a low-energy scale is made. (C) 1997 Elsevier Science B.V.