Search for the Standard Model Higgs Boson in the $ZH\to \nu \overline{\nu }b\overline{b}$ Channel in $5.2{\mathrm{fb}}^{-1}$ of $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

A search is performed for the standard model Higgs boson in $5.2{\mathrm{fb}}^{-1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$, collected with the D0 detector at the Fermilab Tevatron Collider. The final state considered is a pair of $b$ jets and large missing transverse energy, as expected from $p\overline{p}\to ZH\to \nu \overline{\nu }b\overline{b}$ production. The search is also sensitive to the $WH\to \ell \nu b\overline{b}$ channel when the charged lepton is not identified. For a Higgs boson mass of 115 GeV, a limit is set at the 95% C.L. on the cross section multiplied by branching fraction for $[p\overline{p}\to (Z/W)H](H\to b\overline{b})$ that is a factor of 3.7 larger than the standard model value, consistent with the factor of 4.6 expected.

Figure 1

Decision tree outputs for $m_H=115\mathrm{GeV}$: (a) for the MJ DT, and for the SM DTs following the multijet veto for (b) single and (c) double tag. The data are shown as points with error bars. The background contributions are shown as histograms, with codes indicated in the legend in (b). Dibosons are labeled “$VV$,” “$V+\mathrm{l}.\mathrm{f}.$” includes $(W/Z)+(u,d,s,g)$ jets, “$V+\mathrm{h}.\mathrm{f}.$” includes $(W/Z)+(b,c)$ jets, and “Top” includes pair and single top quark production. The distributions for signal ($VH$) are multiplied by factors of 500, 100, and 10 in (a)–(c), respectively.

Figure 2

The observed LLR is shown as a solid black line, the expected LLRs for the background-only and $\mathrm{\text{signal}}+\mathrm{\text{background}}$ hypotheses are shown as black dots and red dashes, respectively, and the heavy green and light yellow shaded areas correspond to 1 and 2 standard deviations (s.d.) around the expected LLR for the background-only hypothesis.