Search for diboson resonances in the llqq final state in pp collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

This note reports a search for heavy resonances decaying into a $WZ$ or $ZZ$ pair using 3.2 fb$^{-1}$ of proton-proton collision data at a centre-of-mass energy of $\sqrt{s}=13$ TeV recorded with the ATLAS detector at the Large Hadron Collider. The search is performed in the final states in which one $Z$ boson decays to a pair of charged leptons (electrons or muons) and the associated $W$ or $Z$ boson decays hadronically and is reconstructed as a single jet. Jet mass and substructure techniques are used to identify jets from the decays of highly boosted $W$ or $Z$ bosons. Resonance structures are searched in the invariant mass distributions of the dilepton and the jet system. No evidence for the production of resonances decaying to $WZ$ or $ZZ$ pair is observed. Upper bounds on the production cross sections times their decay branching ratios to $WZ$ or $ZZ$ pair are derived for heavy resonances in the mass range of $700-3000$ GeV, within the context of heavy vector triplet, Randall-Sundrum graviton, and additional heavy Higgs boson models.