Evidence of $WW$ and $WZ$ Production with $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$ Final States in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We present first evidence for $WW+WZ$ production in $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$ final states at a hadron collider. The data correspond to $1.07{\mathrm{fb}}^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$. The observed cross section for $WW+WZ$ production is $20.2\pm 4.5\mathrm{pb}$, consistent with the standard model and more precise than previous measurements in fully leptonic final states. The probability that background fluctuations alone produce this excess is $<5.4\times {10}^{-6}$, which corresponds to a significance of 4.4 standard deviations.

Figure 1

(a) The RF output distribution from the combined $e\nu q\overline{q}$ and $\mu \nu q\overline{q}$ channels for data and MC predictions following a fit of the MC calculations to data. (b) A comparison of the extracted signal (filled histogram) to background-subtracted data (points), along with the $\pm 1$ standard deviation (s.d.) systematic uncertainty on the background. The residual distance between the data points and the extracted signal, divided by the total uncertainty, is given at the bottom.

Figure 2

(a) The dijet mass distribution from the combined $e\nu q\overline{q}$ and $\mu \nu q\overline{q}$ channels for data and MC predictions following the fit to the RF output. (b) A comparison of the extracted signal (filled histogram) to background-subtracted data (points), along with the $\pm 1$ standard deviation (s.d.) systematic uncertainty on the background. The residual distance between the data points and the extracted signal, divided by the total uncertainty, is given at the bottom.