Measurement of the $WW+WZ$ Production Cross Section Using the $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$ Final State at CDF II

We report two complementary measurements of the $WW+WZ$ cross section in the final state consisting of an electron or muon, missing transverse energy, and jets, performed using $p\overline{p}$ collision data at $\sqrt{s}=1.96\mathrm{TeV}$ collected by the CDF II detector. The first method uses the dijet invariant mass distribution while the second more sensitive method uses matrix-element calculations. The result from the second method has a signal significance of $5.4\sigma$ and is the first observation of $WW+WZ$ production using this signature. Combining the results gives ${\sigma }_{WW+WZ}=16.0\pm 3.3\mathrm{pb}$, in agreement with the standard model prediction.

Figure 1

Dijet invariant mass distribution of reconstructed $W/Z\to jj$ candidates compared to the fitted signal and background components (a), and for the corresponding background subtracted distribution (b).

Figure 2

$M_{jj}$ for events with (a) $\mathrm{EPD}<0.25$, (b) $0.25<\mathrm{EPD}<0.5$, (c) $0.5<\mathrm{EPD}<0.75$, and (d) $\mathrm{EPD}>0.75$.

Figure 3

Observed EPD distribution superimposed on distribution expected from simulated processes.