Low-energy lepton violation from supersymmetric flipped SU(5)

We construct a supersymmetric flipped SU(5)ÅU(1) model which violates $R$ parity and electron number at low energies, through a superpotential term $\frac{1}{2}{C}^{\mathrm{ijk}}{L}_i{L}_j{E}_k^c$. Rotation of the electron and Higgs superfields makes this term also responsible for charged-lepton masses. The model employs a missing-partners mechanism for the Higgs fields and a seesaw mechanism for the neutrinos. It correctly predicts the approximate electron mass and several mass relations, as well as numerical values for the grand unification scale and the $C^{\mathrm{ijk}}$ coefficients. The electron-neutrino Majorana mass is close to experimental limits, and provides constraints. Interesting $Z^0$ decays are predicted: e.g., $Z^0\to e^{-}{\mu }^{+}{e}^{+}{\mu }^{-}$ with invariant mass peaks in the ($e, \mu$) channels.