The hierarchical structure of fermion masses and mixings strongly suggests an underlying family symmetry. In supergravity any familon field spontaneously breaking this symmetry necessarily acquires an F term which contributes to the soft trilinear couplings. We show that, as a result, $\overrightarrow{\mu }e\gamma$ decay can receive large contributions from this source at the level of current experimental bounds, and thus this channel may provide the first indication of supersymmetry and a clue to the structure of the soft breaking sector. Using the mercury electric dipole moment bounds, we find strong bounds on the right handed down quark mixing angles that are inconsistent with models relating them to neutrino mixing angles and favor a near-symmetric form for the magnitude of the down quark mass matrix.

• Received 26 November 2002

DOI:https://doi.org/10.1103/PhysRevD.67.095013