Radiatively Induced Neutrino Mass Matrix in a SUSY GUT Model with   R-Parity Violation
  In order to evade the proton decay which appears when the Zee model is embedded into a SUSY GUT scenario with R-parity violation, a new idea based on a discrete Z_2 symmetry is proposed. Under the symmetry Z_2, the quark and lepton mass matrices are tightly constrained. The admissible form of the radiatively-induced neutrino mass matrix is investigated. 
Yoshio Koide and Ambar Ghosal