$K^{+}\to {\mu }^{+}{\nu }_{\mu }\nu \bar{\nu }$ and $K^{+}\to e^{+}{\nu }_e\nu \bar{\nu }$ decays within the Chiral Perturbation Theory

D. Gorbunov, A. Mitrofanov

Decays $K^{+}\to {\mu }^{+}{\nu }_{\mu }\nu \bar{\nu }$ and $K^{+}\to e^{+}{\nu }_e\nu \bar{\nu }$ are examined to the leading order in momenta in the framework of Chiral Perturbation Theory. P…