Allowable low-energy E6 subgroups from leptogenesis

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+Y′R, 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 the details of the leptogenesis, as well as some salient experimental signatures of the two models.