There are only two viable low-energy E6 subgroups: SU(3)C×SU(2)L×U(1)Y×U(1)N or SU(3)C×SU(2)L×SU(2)R′×U(1)YL+YR′, which would not erase any preexisting lepton asymmetry of
the Universe that may have been created by the decay of heavy singlet
(right-handed) neutrinos or any other mechanism. They are also the two most
favored E6 subgroups from a recent analysis of present neutral-current data.
We study details of the leptogenesis, as well as some salient experimental
signatures of the two models.Comment: 12 page