Finally, for the 2L selection, the two highest leptons are required to be of the same flavour, opposite electric charge, and to have a  above 20. The boson candidates are then reconstructed as the sum of the four-momenta of these two leptons, and the invariant mass of the candidates is required to be compatible with the boson mass ($75 <m_{\ell\ell}< 105\GeV$).

A typical [$\PV\PH(\PH\to \PQc \PAQc)$]{} event has the signature of a vector boson recoiling against a boson with little additional activity. The event selection is designed to retain such events while suppressing background processes as much as possible. In addition to the requirement of a high- vector boson, the QCD multijet background is reduced to negligible levels by demanding the $\ptvecmiss$ to not be aligned with any jet in the event and requiring the azimuthal angular separation $\Delta\phi(\ptvecmiss{}_{\text{trk}},\ptvecmiss)<0.5$ for which $\ptvecmiss{}_{\text{trk}}$ is calculated solely from charged particles. This latter selection reduces the contribution of QCD multijet events that arise from the presence of “fake” $\ptvecmiss$ coming from jet energy mismeasurement in the calorimeters. A significant fraction of the background is suppressed by rejecting events with [$\text{N}^{\text{aj}}_{\text{small-}R}$]{} $>1$ in the 0L and 1L channels, and [$\text{N}^{\text{aj}}_{\text{small-}R}$]{} $>2$ in the 2L 