Search for heavy resonances decaying to a $Z$ boson and a photon in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

Abstract: This Letter presents a search for new resonances with mass larger than 250 GeV, decaying to a $Z$ boson and a photon. The dataset consists of an integrated luminosity of 3.2 fb$^{-1}$ of $pp$ collisions collected at $\sqrt{s} = 13$ TeV with the ATLAS detector at the Large Hadron Collider. The $Z$ bosons are identified through their decays either to charged, light, lepton pairs ($e^+e^-$, $\mu^+\mu^-$) or to hadrons. The data are found to be consistent with the expected background in the whole mass range investigated and upper limits are set on the production cross section times decay branching ratio to $Z\gamma$ of a narrow scalar boson with mass between 250 GeV and 2.75 TeV.