Search for resonant diboson production in the $WW/WZ\to \ell \nu jj$ decay channels with the ATLAS detector at $\sqrt{s}\mathbf{=}7\mathrm{TeV}$

A search for resonant diboson production using a data sample corresponding to $4.7{\mathrm{fb}}^{-1}$ of integrated luminosity collected by the ATLAS experiment at the Large Hadron Collider in $pp$ collisions at $\sqrt{s}=7\mathrm{TeV}$ is presented. The search for a narrow resonance in the $WW$ or $WZ$ mass distribution is conducted in a final state with an electron or a muon, missing transverse momentum, and at least two jets. No significant excess is observed and limits are set using three benchmark models: $WW$ resonance masses below 940 and 710 GeV are excluded at 95% confidence level for spin-2 Randall–Sundrum and bulk Randall–Sundrum gravitons, respectively; $WZ$ resonance masses below 950 GeV are excluded at 95% confidence level for a spin-1 extended gauge model $W^{\prime }$ boson.

Figure 1

Data and background predictions for (a) the lepton $p_{\mathrm{T}}$, (b) $E_{\mathrm{T}}^{\mathrm{miss}}$, and (c) leading jet $p_{\mathrm{T}}$ for preselected events. Electron and muon events are combined in all plots. The rightmost bin contains overflow events.

Figure 2

Observed and predicted $m_{jj}$ distribution in all events satisfying the $p_{\mathrm{T}}$ selection requirements of the reconstructed $W/Z$ bosons. Predictions for an EGM $W^{\prime }$ boson, with the signal cross section enhanced by a factor of 5, are shown for a resonance mass of 1 TeV.

Figure 3

The $m_{\ell \nu jj}$ distribution for the data and the background predictions for events in the $W+\mathrm{\text{jets}}$ background control region. The rightmost bin contains overflow events.

Figure 4

The $m_{\ell \nu jj}$ distribution in data events and the estimated backgrounds for the $t\overline{t}$ background control region. The rightmost bin contains overflow events.

Figure 5

Observed and predicted $m_{\ell \nu jj}$ distributions shown for all (a) $e\nu jj$ and (b) $\mu \nu jj$ events satisfying the signal selection requirements. Predictions for an EGM $W^{\prime }$ boson are shown for a resonance mass of 1 TeV. The rightmost bin contains overflow events.

Figure 6

Observed and expected 95% C.L. upper limits on $\sigma (pp\to G^{*})\times \mathrm{BR}(G^{*}\to WW)$ for (a) an RS1 $G^{*}$ and (b) a bulk RS $G^{*}$, and on $\sigma (pp\to W^{\prime })\times \mathrm{BR}(W^{\prime }\to WZ)$ for (c) an EGM $W^{\prime }$ boson.

Figure 7

The 95% C.L. observed and expected excluded regions of the EGM coupling strength scaling factor $c_{\mathrm{EGM}}$ as a function of $m_{W^{\prime }}$. The green and yellow band correspond to the $\pm 1$ and $\pm 2\sigma$ intervals, respectively.