Theory of rare K decays

Abstract

I review rare kaon decays. I introduce the flavor problem and possible solutions. Very rare kaon decays like K → πvv¯ are very important to this purpose: we study also K → πl+l-, K → ππee where chiral dynamics is important to disentangle short distance effects. We discuss also the decays K0 → μ+μ-, which have received recently some attention due to the measurement by LHCB.