This paper reports a search for nonstandard model topquark resonances, $Z^{\prime }$, decaying to $t\overline{t}\to W^{+}b{W}^{-}\overline{b}$, where both $W$ decay to quarks. We examine the top-antitop quark invariant mass spectrum for the presence of narrow resonant states. The search uses a data sample of $p\overline{p}$ collisions at a center of mass energy of 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron, with an integrated luminosity of $2.8{\mathrm{fb}}^{-1}$. No evidence for top-antitop quark resonant production is found. We place upper limits on the production cross section times branching ratio for a specific topcolor assisted technicolor model in which the $Z^{\prime }$ has a width of ${\Gamma }_{Z^{\prime }}=0.012M_{Z^{\prime }}$. Within this model, we exclude a $Z^{\prime }$ boson with masses below $805\mathrm{GeV}/c^2$ at the 95% confidence level.

• Received 25 August 2011

DOI:https://doi.org/10.1103/PhysRevD.84.072003