Search for high-mass resonances in $Z\gamma \rightarrow e^+e^-\gamma/\mu^+\mu^-\gamma$ final states in proton-proton collisions at $\sqrt{s}=13~\mathrm{TeV}$

A search for a heavy resonance decaying to $Z\gamma$, with the Z boson further decaying to a pair of electrons or muons is presented. The search makes use of 13 TeV proton-proton collision data collected in 2016 by the CMS experiment at the LHC, corresponding to an integrated luminosity of $12.9~\mathrm{fb}^{-1}$. The analysis estimates the background directly from data, through an unbinned likelihood fit. No significant excess over the background-only hypothesis is observed, therefore limits at $95\%$ confidence level are set on the production cross section of particles with a mass between $300~\mathrm{GeV}$ and $2~\mathrm{TeV}$, in the narrow width approximation.