Date of this Version
PHYSICAL REVIEW LETTERS 107, 271802 (2011); DOI: 10.1103/PhysRevLett.107.271802
A search for pair-produced heavy vectorlike charge-2/3 quarks, T, in pp collisions at a center-of-mass energy of 7 TeV, is performed with the CMS detector at the LHC. Events consistent with the flavorchanging- neutral-current decay of a T quark to a top quark and a Z boson are selected by requiring two leptons from the Z-boson decay, as well as an additional isolated charged lepton. In a data sample corresponding to an integrated luminosity of 1.14 fb-1, the number of observed events is found to be consistent with the standard model background prediction. Assuming a branching fraction of 100% for the decay T → tZ, a T quark with a mass less than 475 GeV/c2 is excluded at the 95% confidence level.