Search for Dark Photons in ZH Decays at $\sqrt{s}=13~\mathrm{TeV}$

A search is presented for decays of a Higgs boson to an invisible particle together with an isolated photon, using the CMS experiment at the Large Hadron Collider. The Higgs boson is produced in association with a Z boson. The analysis is performed using a dataset recorded in 2016-18 corresponding to an integrated luminosity of $137.4~\mathrm{fb}^{-1}$, at a center-of-mass energy of $13~\mathrm{TeV}$. No significant excess of events above the standard model expectation is found, and the results are interpreted to place limits on the cross section times branching fraction of such decays of the Higgs boson.