Measurement of the very rare $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ decay

NA62 Collaboration

The NA62 experiment reports the branching ratio measurement BR$(K^{+}\to {\pi }^{+}\nu \bar{\nu })=(10.6_{-3.4}^{+4.0}{|}_{\mathrm{stat}}\pm 0.9_{\mathrm{syst}})\times 10^{-11}$ at 68% CL, base…