Hierarchies of R-violating interactions from family symmetries

We investigate the possibility of constructing models of R-violating LQ anti D Yukawa couplings using a single U(1) flavour-symmetry group and supermultiplet charge assignments that are compatible with the known hierarchies of quark and lepton masses. The mismatch of mass and current eigenstates inferred from the known charged-current mixing induces the propagation of strong phenomenological constraints on some R-violating couplings to many others. Applying these constraints, we look for flavour-symmetry models that are consistent with different squark-production hypotheses devised to explain the possible HERA large-Q2 anomaly. The e+d→t interpretation of the HERA data is accommodated relatively easily, at the price of postulating an extra parity. The e+s→t interpretation of the events requires models to have only small (2,3) mixing in the down quark sector. The e+d→c mechanism cannot be accommodated without large violations of squark-mass universality, due to the very strong experimental constraints on R-violating operators. We display a model in which baryon decay due to dangerous dimension-five operators is automatically suppressed. (orig.)