  Taking the reported high-Q^2 anomaly at HERA as a signal of new physics, we
show that several independent considerations point towards s-channel leptoquark
production as the most attractive interpretation. We argue that even this
option is highly constrained by flavor-changing processes: the couplings must
be accurately diagonal in the quark and lepton mass eigenstate basis and should
preserve individual quark and lepton family numbers. We propose a dynamical
mechanism that might produce this pattern; it has distinctive experimental
consequences.

High Energy Physics - Phenomenology;High Energy Physics - Experiment