A model with chiral quarks of electric charges −4/3 and 5/3

Abstract

We present a new model based on the SU(3)⨂SU(2)⨂U(1) symmetry, in which there is a new consistent set of chiral fermion fields that renders the model free from anomalies. The new fermions do not share the usual family structure of the Standard Model and some of them have exotic electric charges, as the quarks X and Y with electric charge 5/3 and −4/3, respectively. Interestingly, the model contains a new heavy neutral lepton which may be a dark matter candidate. Two Higgs doublets are present in our construction, so that two CP even scalars are present in the model particle spectrum. One of them is similar to the Standard Model Higgs boson, while the other one couples mainly with the new exotic fermions. We performed a discovery analysis showing that the 8 TeV LHC can find the Y quark from single and pair production with masses from 300 GeV up to ~ 750 GeV. We also show that the new spectrum does not contribute significantly to the oblique EW parameters, and that dangerous flavor changing neutral currents are suppressed. Characteristic signatures from the other new fermions in the model are also commented.