Recent Results from Kaon Physics

A review of recent results on kaon physics is presented.

Firstly, results on kaon semileptonic decays are summarised and a value for the CKM matrix element $V_{us}$ is extracted, compatible at 1 $\sigma$ with that expected from CKM unitarity. Then precision data on $K_{l3}$ and $K_{l2}$ decay rates are presented and tests for new physics searches are discussed.

Finally, preliminary results on the $K_{e4}$ decay $K^\pm \rightarrow \pi^+ \pi^- e^\pm \nu$ are summarised. The $\pi\pi$ scattering lengths $a^0_0$ and $a^2_0$ can be extracted from the $K_{e4}$ phase shift and from the slope change in the $M^2_{00}$ distribution of $K^\pm \rightarrow \pi^0 \pi^0 \pi^\pm $ decays. Future prospects on kaon physics are also briefly revised.

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