Physics beyond the standard model with kaons at NA62

The NA62 experiment at CERN Super Proton Synchrotron was designed to measure BR(K+ → π+νv¯) with an in-fight technique, never used before for this measurement. This decay is characterised by a very precise prediction in the Standard Model. Its branching ratio, which is expected to be less than 10−10, is one of the best candidates to indicate indirect effects of new physics beyond SM at the highest mass scales. NA62 result on K+ → π+νv¯ from the full 2016 data set is described.Also a search for an invisible dark photon A′ has been performed, exploiting the efficient photon-veto capability and high resolution tracking of the NA62. The signal stems from the chain K+ → π+π0 followed by π0 → A′γ. No significant statistical excess has been identified. Upper limits on the dark photon coupling to the ordinary photon as a function of the dark photon mass have been set, improving on the previous limits over the mass range 60 - 110 MeV/c2.