$Z$-boson decays into an invisible dark photon at the LHC, HL-LHC and future lepton colliders

M. Cobal, C. De Dominicis, M. Fabbrichesi +4

We study the decay of the $Z$ vector boson into a photon and a massless (invisible) dark photon in high-energy collisions. The photon can be used as trigger for the event, while th…