Search for $Wb\overline{b}$ and $WH$ Production in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{T}\mathrm{e}\mathrm{V}$

We present a search for $Wb\overline{b}$ production in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{T}\mathrm{e}\mathrm{V}$ in events containing one electron, an imbalance in transverse momentum, and two $b$-tagged jets. Using $174{\mathrm{p}\mathrm{b}}^{-1}$ of integrated luminosity accumulated by the D0 experiment at the Fermilab Tevatron collider, and the standard-model description of such events, we set a 95% C.L. upper limit on $Wb\overline{b}$ production of 6.6 pb for $b$ quarks with transverse momenta $p_T^b>20\mathrm{G}\mathrm{e}\mathrm{V}$ and $b\overline{b}$ separation in pseudorapidity-azimuth space $\Delta {\mathcal{R}}_{bb}>0.75$. Restricting the search to optimized $b\overline{b}$ mass intervals provides upper limits on $WH$ production of 9.0–12.2 pb for Higgs-boson masses of 105–135 GeV.

Figure 1

Distribution of the dijet invariant mass for $W+2$ jet events, when at least one jet is $b$ tagged, compared to expectation (cumulative). The other SM backgrounds include single-top events. The simulated contributions are normalized to the integrated luminosity of the data.

Figure 2

Distribution of the dijet invariant mass for $W+2$ $b$-tagged events, compared to expectation (cumulative). The simulated contributions are normalized to the integrated luminosity of the data. The expectation for a 115 GeV Higgs boson from $WH$ production is also shown.

Figure 3

95% C.L. upper limit on $\sigma (p\overline{p}\to WH)\times BR(H\to b\overline{b})$ compared to the SM expectation at $\sqrt{s}=1.96\mathrm{T}\mathrm{e}\mathrm{V}$, and to CDF results [20], which were obtained at $\sqrt{s}=1.8\mathrm{T}\mathrm{e}\mathrm{V}$. The predicted $WH$ cross section at 1.96 TeV is approximately 15% larger than that at 1.8 TeV.