Lepton number conservation, long-lived quarks and superweak bileptonic decays

In the upcoming LHC Run 2, at s∼13 TeV, it is suggested to seek unusually charged (Q=−4/3 and +5/3) quarks with mass MQ∼3 TeV which carry lepton number (L=+2 and −2 respectively) and decay superweakly to a bilepton Y with mass MY∼2.5 TeV and a usual quark. These long-lived decays will have displaced decay vertices and produce a striking final state in pp which contains two separated jets together with two pairs of correlated like-sign charged leptons. Such a process was inaccessible energetically in LHC Run 1 with s∼8 TeV. The simplest theoretical explanation is the 331-model which has new physics necessarily below 4 TeV and which explains the existence of three families by anomaly cancellation.