Like-sign dilepton signals from a leptophobic Z' boson

A new leptophobic neutral gauge boson Z’ with small mixing to the Z can have a mass as light as M_Z’ ~ 350 GeV, and still have escaped detection at LEP and Tevatron. Such a Z’ boson can be derived from E6 and, if the new heavy neutrino singlets in the 27 representation are lighter than M_Z’/2, the process p p(pbar) -> Z’ -> NN -> l± l± X is observable. Indeed, this new signal could explain the small excess of like-sign dileptons found at Tevatron. Implications for LHC are also discussed. In particular, the Tevatron excess could be confirmed with less than 1 fb-1, and leptophobic Z’ masses up to 2.5 TeV can be probed with 30 fb-1.