Pair production of heavy Q=2/3 singlets at LHC

We examine the LHC discovery potential for new Q=2/3 quark singlets T in the process gg,qq -> T Tbar -> W+ b W- bbar, with one W boson decaying hadronically and the other one leptonically. A particle-level simulation of this signal and its main backgrounds is performed, showing that heavy quarks with masses of 500 GeV or lighter can be discovered at the 5 sigma level after a few months of running, when an integrated luminosity of 3 fb^-1 is collected. With a luminosity of 100 fb^-1, this process can signal the presence of heavy quarks with masses up to approximately 1 TeV. Finally, we discuss the complementarity among T Tbar, Tj production and indirect constraints from precise electroweak data in order to discover a new quark or set bounds on its mass.