Search for a fourth generation t′ quark in pp̄ collisions at √s=1.96TeV

We present a search for pair production of a fourth generation t ′ quark and its antiparticle, followed by their decays to a W boson and a jet, based on an integrated luminosity of 5.3fb-1 of proton-antiproton collisions at √s=1.96TeV collected by the D0 Collaboration at the Fermilab Tevatron Collider. We set upper limits on the t′t̄′ production cross section that exclude at the 95% C.L. a t′ quark that decays exclusively to W+jet with a mass below 285 GeV. We observe a small excess in the μ+jets channel which reduces the mass range excluded compared to the expected limit of 320 GeV in the absence of a signal. © 2011 American Physical Society.