We propose new mechanisms for understanding neutrino masses in superstring models that contain ${\mathrm{E}}_6$-singlet zero-mass fields after compactification. We show that the low-energy gauge group of these models can be phenomenologically acceptable. We then comment on ΔB=1 and ΔB=2 baryon-number-violating processes in these models.

• Received 3 March 1986

DOI:https://doi.org/10.1103/PhysRevD.34.1642