Search for the Standard Model Higgs Boson in Associated $WH$ Production in $9.7{\mathrm{fb}}^{-1}$ of $p\overline{p}$ Collisions with the D0 Detector

We present a search for the standard model Higgs boson in final states with a charged lepton (electron or muon), missing transverse energy, and two or three jets, at least one of which is identified as a $b$-quark jet. The search is primarily sensitive to $WH\to \ell \nu b\overline{b}$ production and uses data corresponding to $9.7{\mathrm{fb}}^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron $p\overline{p}$ Collider at $\sqrt{s}=1.96\mathrm{TeV}$. We observe agreement between the data and the expected background. For a Higgs boson mass of 125 GeV, we set a 95% C.L. upper limit on the production of a standard model Higgs boson of $5.2\times {\sigma }_{\mathrm{SM}}$, where ${\sigma }_{\mathrm{SM}}$ is the standard model Higgs boson production cross section, while the expected limit is $4.7\times {\sigma }_{\mathrm{SM}}$.

Figure 1

(a) The dijet mass distribution for all $b$-tag categories and two-jet exclusive events. (b) The final BDT output for two medium $b$-tagged events and (c) two tight $b$-tagged events. Electron and muon channels are combined. The Higgs boson signal is shown for $M_H=125\mathrm{GeV}$. Signal events are scaled by a factor of 100 in (a) and 20 in (b) and (c).

Figure 2

Distribution of the difference between the data and background expectation of the final BDT discriminant output for $M_H=125\mathrm{GeV}$ for the background-only model, shown with statistical uncertainties (points with error bars). The solid lines represent the $\pm 1\mathrm{s}.\mathrm{d}.$ systematic uncertainty after constraining with the data. The darker shaded region is the expected final BDT distribution for a SM Higgs signal for $M_H=125\mathrm{GeV}$. Here we combine BDT discriminant bins from each channel according to the bins’ ${log}_{10}(s/b)$ values.

Figure 3

Log-likelihood ratio for the background-only model (${\mathrm{LLR}}_B$, with 1 and 2 s.d. uncertainty bands), $\mathrm{\text{signal}}+\mathrm{\text{background}}$ model (${\mathrm{LLR}}_{S+B}$), and data (${\mathrm{LLR}}_{\mathrm{obs}}$) versus $M_H$.