THE SUPERSYMMETRIC FLAVOR PROBLEM

The supersymmetric SU(3) x SU(2) x U(1) theory with minimal particle c ontent and general soft supersymmetry breaking terms has 110 physical parameters in its flavor sector: 30 masses, 39 real mixing angles and 41 phases. The absence of an experimental indication for the plethora of new parameters places severe constraints on theories possessing Pla nck- or GUT-mass particles and suggests that theories of flavor confli ct with naturalness, We illustrate the problem by studying the process es mu --> e + gamma and K-0 - ($) over bar K-0 mixing which are very s ensitive probes of Planckian physics: a single Planck-mass particle co upled to the electron or the muon with a Yukawa coupling comparable to the gauge coupling typically leads to a rate for mu --> e + gamma exc eeding the present experimental limits. A possible solution is that th e messengers which transmit supersymmetry breaking to the ordinary par ticles are much lighter than M(P1).