A left-right-symmetric extension of the standard electroweak interaction model is presented in which baryon- ($B$-) and lepton- ($\mathcal{L}$-) number conservation are considered as spontaneously broken gauge symmetries. The gauge, global, and the mixed gauge-gravitational anomalies in the model are canceled by invoking new fermion matter that carries baryon as well as lepton numbers. We find a class of models in which the exotic fermions carry the same electric charges as the $N$ families of conventional fermions but different $B$ and $\mathcal{L}$ charges. The Higgs structure in this case allows a light massive neutral boson with a lower bound of 120 GeV.

• Received 5 September 1989

DOI:https://doi.org/10.1103/PhysRevD.41.1636