Paper detail

New physics limits from kaon decays

Searches for lepton flavour violation and lepton number violation in kaon decays by the NA62 and NA48/2 experiments at CERN are presented. A new measurement of the ratio of charged kaon leptonic decay rates $R_K=Γ(K_{e2})/Γ(K_{\mu2})$ to sub-percent relative precision is discussed. An improved upper limit on the lepton number violating $K^\pm\rightarrowπ^\mpμ^\pmμ^\pm$ decay rate is also reported. The future 10% precision measurement of the branching ratio of the ultra-rare kaon decay $K^+\rightarrowπ^+ν\barν$ with the NA62 experiment is finally reviewed.