Search for Higgs Boson Production in Dilepton and Missing Energy Final States with $5.4{\mathrm{fb}}^{-1}$ of $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

A search for the standard model Higgs boson is presented using events with two charged leptons and large missing transverse energy selected from $5.4{\mathrm{fb}}^{-1}$ of integrated luminosity in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ collected with the D0 detector at the Fermilab Tevatron collider. No significant excess of events above background predictions is found, and observed (expected) upper limits at 95% confidence level on the rate of Higgs boson production are derived that are a factor of 1.55 (1.36) above the predicted standard model cross section at $m_H=165\mathrm{GeV}$.

Figure 1

(a) The dilepton invariant mass after preselection; (b) the $\Delta \varphi (\ell ,\ell )$ angle after final selection; and (c) the neural network output after final selection. The signal is shown for $m_H=165\mathrm{GeV}$. The systematic uncertainty is shown after fitting (see text for details).

Figure 2

(a) Data after subtracting the fitted background (points) and SM signal expectation (filled histogram) as a function of the NN output for $m_H=165\mathrm{GeV}$. Also shown is the $\pm 1$ standard deviation (s.d.) band on the total background after fitting. (b) Observed LLR (solid line), expected LLR for background-only hypothesis (dashed line), and $\mathrm{\text{signal}}+\mathrm{\text{background}}$ hypothesis (dotted line). (c) Upper limit on Higgs boson production cross section at 95% C.L. expressed as a ratio to the SM cross section. The one and two s.d. bands around the curve corresponding to the background-only hypothesis are also shown.