Search for New Physics in High Mass Electron-Positron Events in ppbar Collisions at sqrt(s) = 1.96 TeV

Abstract

We report the results of a search for a narrow resonance in electron-positron events in the invariant mass range of 150-950 GeV/c^2 using 1.3 fb^-1 of ppbar collision data at sqrt(s) = 1.96 TeV collected by the CDF II detector at Fermilab. No significant evidence of such a resonance is observed and we interpret the results to exclude the standard model-like Z' with a mass below 923 GeV/c^2 and the Randall-Sundrum graviton with a mass below 807 GeV/c^2 for k/M_pl=0.1, both at the 95% confidence level. Combining with di-photon data excludes the Randall-Sundrum graviton for masses below 889 GeV/c^2 for k/M_pl=0.1.

Figures (4)

• Figure 1: The measured $ee$ mass spectrum with the expected background for the CC and CP channels combined. The backgrounds are displayed cumulatively. There are no observed events above 550 $\mathrm{Ge V}\!/c^2$.
• Figure 2: The probability that the background alone could give rise to the observed number of events in a mass window equal to the width of a narrow resonance in the CDF detector. The expected range and the $3\sigma$ evidence line are defined in the text. The region $550-950$$\mathrm{Ge V}\!/c^2$ is not shown as no events are observed in data and therefore the p-value is always 1 in this region.
• Figure 3: The observed and expected limits on the $\sigma \cdot {\cal B}(X \rightarrow ee)$ of a spin-1 particle.
• Figure 4: The limits on $\sigma \cdot {\cal B}(G \rightarrow ee)$ (top) and $k/\bar{M}_{pl}$ (bottom) for a RS graviton in the $ee$, $\gamma\gamma$ channels separately and combined.