Search for a $W^{\mathbf{\prime }}$ or Techni-$\rho$ Decaying into $WZ$ in $pp$ Collisions at $\sqrt{s}\mathbf{=}7\mathrm{TeV}$

A search is performed in $pp$ collisions at $\sqrt{s}=7\mathrm{TeV}$ for exotic particles decaying via $WZ$ to final states with electrons and muons. The data sample corresponds to an integrated luminosity of approximately $5{\mathrm{fb}}^{-1}$. No significant excess is observed in the data above the expected standard model background. Upper bounds at $95\%$ confidence level are set on the production cross section of the $W^{\prime }$ boson described by the sequential standard model and on the $W^{\prime }$ $WZ$ coupling. $W^{\prime }$ bosons with masses below 1143 GeV are excluded. Limits are also set in the context of low-scale technicolor models, under a range of assumptions concerning the model parameters.

Figure 1

Distribution of the $WZ$ invariant mass (top) before application of the $L_{\mathrm{T}}$ requirement and (bottom) after applying the $L_{\mathrm{T}}$ requirement ($L_{\mathrm{T}}>290\mathrm{GeV}$) for the $W^{\prime }$ mass point at 600 GeV.

Figure 2

Expected and observed $95\%$ C.L. upper limits on $\sigma \times \mathcal{B}(W^{\prime }/{\rho }_{\mathrm{TC}}\to 3\ell \nu )$ as a function of the resonance mass for $W^{\prime }$ or ${\rho }_{\mathrm{TC}}$, along with the $1\sigma$ and $2\sigma$ combined statistical and systematic expected variation shown as green (dark) and yellow (light) bands, respectively. The theoretical cross sections, with PDF uncertainties, include a mass-dependent next-to-next-to-leading-order $K$ factor. The LSTC cross sections assume the relationship $M({\pi }_{\mathrm{TC}})=\frac{3}{4}M({\rho }_{\mathrm{TC}})-25\mathrm{GeV}$.

Figure 3

Exclusion region at $95\%$ C.L. for LSTC as a function of the ${\rho }_{\mathrm{TC}}$ and ${\pi }_{\mathrm{TC}}$ masses.

Figure 4

Upper limit at $95\%$ C.L. on the strength of the $W^{\prime }$ $WZ$ coupling normalized to the SSM prediction, as a function of the $W^{\prime }$ mass. The $1\sigma$ and $2\sigma$ combined statistical and systematic expected variation is shown as green (dark) and yellow (light) bands, respectively. PDF uncertainties on the theoretical cross section are not included.