Anomalous U(1) symmetry and lepton flavor violation

Abstract

We show that in a large class of models based on anomalous U(1) symmetry which addresses the fermion mass hierarchy problem, leptonic flavor changing processes are induced that are in the experimentally interesting range. The flavor violation occurs through the renormalization group evolution of the soft SUSY breaking parameters between the string scale and the U(1) A breaking scale. We derive general expressions for the evolution of these parameters in the presence of higher-dimensional operators. Several sources for the flavor violation are identified: flavor-dependent contributions to the soft masses from the U(1) A gaugino, scalar mass corrections proportional to the trace of U(1) A charge, non-proportional A-terms from vertex corrections, and the U(1) A D-term. Quantitative estimates for the decays μ→ eγ and τ→ μγ are presented in supergravity models which accommodate the relic abundance of neutralino dark matter.