Search for aVectorlike Quarkwith Charge 2/3 in t + Z Events from pp Collisions at √s = 7 TeV

Authors

S. Chatrchyan, Yerevan Physics Institute, Yerevan, Armenia
Kenneth A. Bloom, University of Nebraska-LincolnFollow
S. Bose, University of Nebraska-LincolnFollow
Jamila Butt, University of Nebraska-Lincoln
Daniel R. Claes, University of Nebraska-LincolnFollow
Aaron Dominguez, University of Nebraska-LincolnFollow
Michael Eads, University of Nebraska-LincolnFollow
P. Jindal, University of Nebraska-Lincoln
J. Keller, University of Nebraska-LincolnFollow
T. Kelly, University of Nebraska-Lincoln
Ilya Kravchenko, University of Nebraska-LincolnFollow
J. Lazo-Flores, University of Nebraska-LincolnFollow
H. Malbouisson, University of Nebraska-Lincoln
Sudhir Malik, University of Nebraska-LincolnFollow
Gregory Snow, University of Nebraska-LincolnFollow

Date of this Version

2011

Citation

PHYSICAL REVIEW LETTERS 107, 271802 (2011); DOI: 10.1103/PhysRevLett.107.271802

Comments

Copyright 2011 CERN, for the CMS Collaboration

Abstract

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.