Limits on the production of narrow tt¯ resonances in pp¯ collisions at s=1.96 TeV

Le résumé fourni par la source

We search for evidence of resonant top quark pair production in 955 ${\mathrm{pb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ recorded with the CDF II detector at the Fermilab Tevatron. For fully reconstructed candidate $t\overline{t}$ events triggered on leptons with large transverse momentum and containing at least one identified $b$-quark jet, we compare the invariant mass spectrum of $t\overline{t}$ pairs to the expected superposition of standard model $t\overline{t}$, non-$t\overline{t}$ backgrounds, and a simple resonance model based on a sequential ${Z}^{\ensuremath{'}}$ boson. We establish upper limits for $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}{Z}^{\ensuremath{'}})\ifmmode\cdot\else\textperiodcentered\fi{}Br({Z}^{\ensuremath{'}}\ensuremath{\rightarrow}t\overline{t})$ in the ${Z}^{\ensuremath{'}}$ mass interval from $450\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ to $900\text{ }\text{ }\mathrm{GeV}/{c}^{2}$. A topcolor leptophobic ${Z}^{\ensuremath{'}}$ is ruled out below $720\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, and the cross section of any narrow ${Z}^{\ensuremath{'}}$-like state decaying to $t\overline{t}$ is found to be less than 0.64 pb at 95% C.L. for ${M}_{{Z}^{\ensuremath{'}}}$ above $700\text{ }\text{ }\mathrm{GeV}/{c}^{2}$.

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