Search for Resonant $t\overline{t}$ Production in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We report on a search for narrow-width particles decaying to a top and antitop quark pair. The data set used in the analysis corresponds to an integrated luminosity of $680{\mathrm{pb}}^{-1}$ collected with the Collider Detector at Fermilab in run II. We present 95% confidence level upper limits on the cross section times branching ratio. Assuming a specific top-color-assisted technicolor production model, the leptophobic $Z^{\prime }$ with width ${\Gamma }_{Z^{\prime }}=0.012M_{Z^{\prime }}$, we exclude the mass range $M_{Z^{\prime }}<725\mathrm{GeV}/c^2$ at the 95% confidence level.

Figure 1

Reconstructed $M_{t\overline{t}}$ distributions for two simulated standard model backgrounds. We plot the samples with the “hardest” ($t\overline{t}$) and the “softest” (diboson) spectrum (normalized to unity); all the others lie in between. The inset shows the reconstructed $M_{t\overline{t}}$ distributions for five signal samples.

Figure 2

The reconstructed $M_{t\overline{t}}$ spectrum (data) and the standard model prediction in the search region above $400\mathrm{GeV}/c^2$. The inset shows the same distributions in logarithmic scale.

Figure 3

Predicted and experimental 95% C.L. upper limits using data corresponding to $680{\mathrm{pb}}^{-1}$ of integrated luminosity, together with the leptophobic top-color $Z^{\prime }$ cross section prediction. Dark and light areas define the $1\sigma$ and $2\sigma$ ranges for the expected limits. The arrow marks the mass upper limit.