The supersymmetric flavor problem Original Research Article

The supersymmeri SU(3) × SU(2) × U(1) theory with minimal particle content 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 Planck- or GUT-mass particles and suggests that theories of flavor conflict with naturalness. We illustrate the problem by studying the processes μ å e + γ and K0 − K0 mixing which are very sensitive probes of Planckian physics: a single Planck-mass particle coupled to the electron or the muon with a Yukawa coupling comparable to the gauge coupling typically leads to a rate for μ → e + γ exceeding the present experimental limits. A possible solution is that the messengers which transmit supersymmetry breaking to the ordinary particles are much lighter than Mpl.