Search for a Narrow ttbar Resonance in ppbar Collisions at sqrt{s}=1.96 TeV

Abstract

We report a search for a narrow ttbar resonance that decays into a lepton+jets final state based on an integrated luminosity of 5.3/fb of proton-antiproton collisions at sqrt{s}=1.96 TeV collected by the D0 Collaboration at the Fermilab Tevatron Collider. We set upper limits on the production cross section of such a resonance multiplied by its branching fraction to ttbar which we compare to predictions for a leptophobic topcolor Z' boson. We exclude such a resonance at the 95% confidence level for masses below 835 GeV.

Figures (3)

• Figure 1: Distributions of $m_{t\bar{t}}$ for resonances with mass $M_X$, normalized to the predicted $\sigma B$ from Table \ref{['tab:limits']}.
• Figure 2: Distribution of $m_{t\bar{t}}$ for events that pass the final event selection with (a) exactly 3 jets and (b) at least 4 jets, compared with expectations for standard model processes and a 950 GeV resonance signal with the best fitted $\sigma B=0.10$ pb. The highest bin in each histogram shows the number of events with $m_{t\bar{t}}>1175$ GeV.
• Figure 3: Observed and expected upper limits on cross section times branching fraction $\sigma B$ for a narrow $t\bar{t}$ resonance as a function of the resonance mass. The shaded regions around the expected limit represent the $\pm$1 and $\pm$2 standard deviation bands. The solid line shows the predicted topcolor $Z'$ production cross section assuming $B(Z'\rightarrow t\bar{t})=100\%$.