Searches for exclusive Higgs and $Z$ boson decays into a vector quarkonium state and a photon using $139$ fb${}^{-1}$ of ATLAS $\sqrt{s}=13$ TeV proton$-$proton collision data

ATLAS Collaboration

Searches for the exclusive decays of Higgs and $Z$ bosons into a vector quarkonium state and a photon are performed in the ${\mu }^{+}{\mu }^{-}\gamma$ final state with a proton$-$proton collision d…