Search for a Neutral Higgs Boson Decaying to a $W$ Boson Pair in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We present the results of a search for standard model Higgs boson production with decay to $W{W}^{*}$, identified through the leptonic final states $e^{+}{e}^{-}\overline{\nu }\nu ,e^{\pm }{\mu }^{\mp }\overline{\nu }\nu$ and ${\mu }^{+}{\mu }^{-}\overline{\nu }\nu$. This search uses $360{\mathrm{pb}}^{-1}$ of data collected from $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ by the upgraded Collider Detector at Fermilab (CDF II). We observe no signal excess and set 95% confidence level upper limits on the production cross section times branching ratio for the Higgs boson to $W{W}^{*}$ or any new scalar particle with similar decay products. These upper limits range from 5.5 to 3.2 pb for Higgs boson masses between 120 and $200\mathrm{GeV}/c^2$.

Figure 1

Dilepton azimuthal distributions for SM backgrounds, $HWW$ signal, and data, for two Higgs masses: $140\mathrm{GeV}/c^2$ (top panel) and $160\mathrm{GeV}/c^2$ (bottom panel). Note that the Higgs signal is scaled by a factor of 10 and is not included in the cumulative background distributions.

Figure 2

Summary of the run II CDF 95% C.L. upper limits on $\sigma (p\overline{p}\to H)\times \mathrm{BR}(H\to W{W}^{*})$. Shown for comparison are the standard model prediction, the fourth generation model prediction [8], and the region excluded by the LEP experiments. The prediction for the fourth generation model assumes that fourth family fermions have a mass $m_4=200\mathrm{GeV}/c^2$.