Search for the lepton flavor violating decay of a Higgs boson in the $\mathrm{e}\mu$ final state in proton-proton collisions at $\sqrt{s} = 13~\mathrm{TeV}$

A search for the lepton-flavor violating decay of a Higgs boson or other exotic resonances with a mass from $110-160~\mathrm{GeV}$ to an $\mathrm{e}^{\pm}\mu^{\mp}$ pair is presented. The search is performed with a proton-proton collision data set at a center-of-mass energy of $13~\mathrm{TeV}$ collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of $138~\mathrm{fb}^{-1}$. No significant excess is observed for the standard model Higgs boson with a mass at around $125~\mathrm{GeV}$. The observed (expected) upper limit on the branching fraction for the standard model Higgs boson is determined to be $4.4\ (4.7)\times10^{-5}$ at $95\%$ confidence level, the most stringent limit set thus far from direct searches. An excess of events over the expected background is observed at an electron-muon invariant mass of approximately $146~\mathrm{GeV}$ with a global (local) significance of 2.8 (3.8) standard deviations.