The seesaw mechanism is implemented for all quarks and leptons in the standard model of strong and electroweak interactions based on the gauge group SU(3${)}_{\mathrm{c}}$×SU(2${)}_{\mathrm{L}}$×U(1). This requires the introduction of a set of new fermions that are singlets of the weak-interaction group SU(2${)}_{\mathrm{L}}$. Two models are constructed: one with discrete symmetries and another with Peccei-Quinn symmetry. The Higgs sector of the second model is identical to the Dine-Fischler-Srednicki model.

• Received 21 July 1988

DOI:https://doi.org/10.1103/PhysRevD.39.351