Search for Leptonic Decays of Dark Photons at NA62

The NA62 experiment at CERN, configured in beam-dump mode, has searched for dark photon decays in flight to electron-positron pairs using a sample of $1.4\times {10}^{17}$ protons on dump collected in 2021. No evidence for a dark photon signal is observed. The combined result for dark photon searches in lepton-antilepton final states is presented and a region of the parameter space is excluded at 90% CL, improving on previous experimental limits for dark photon mass values between 50 and 600 MeV$\mathrm{/}{c}^2$ and coupling values in the range ${10}^{-6}$ to $4\times {10}^{-5}$. An interpretation of the $e^{+}{e}^{-}$ search result in terms of the emission and decay of an axion-like particle is also presented.