Measurement of the $W^+W^-$ Production Cross Section and Search for Anomalous $WWγ$ and $WWZ$ Couplings in $p \bar p$ Collisions at $\sqrt{s} = 1.96$ TeV

Abstract

This Letter describes the current most precise measurement of the $W$ boson pair production cross section and most sensitive test of anomalous $WWγ$ and $WWZ$ couplings in $p \bar p$ collisions at a center-of-mass energy of 1.96 TeV. The $WW$ candidates are reconstructed from decays containing two charged leptons and two neutrinos, where the charged leptons are either electrons or muons. Using data collected by the CDF II detector from 3.6 fb$^{-1}$ of integrated luminosity, a total of 654 candidate events are observed with an expected background contribution of $320 \pm 47$ events. The measured total cross section is $σ(p \bar p \to W^+ W^- + X) = 12.1 \pm 0.9 \textrm{(stat)} ^{+1.6}_{-1.4} \textrm{(syst)}$ pb, which is in good agreement with the standard model prediction. The same data sample is used to place constraints on anomalous $WWγ$ and $WWZ$ couplings.

Figures (2)

• Figure 1: The $LR_{WW}$ distributions for the signal ($W^+W^-$) and background processes after a maximum likelihood fit to the data.
• Figure 2: Leading-lepton $p_T$ distribution for data compared to the SM expectation. Also shown is how the expectation would be modified by anomalous couplings near the observed limits.