Study of the DecaysK→ll¯andK→πll¯

A general discussion is presented of polarization and angular distributions in the decays $K\to l\overline{l}$ and $K\to \pi l\overline{l}$. Our main motivation is to examine the ways in which such distributions may reveal the influence of higher-order weak effects as distinct from electromagnetic effects. We focus on the relatively most favorable case of the $K_L$ modes. Under the neglect of the small $\mathrm{CP}$ impurity in the composition of $K_L$ and $K_S$ states, and of electromagnetic final-state interactions, these modes provide interesting tests for $\mathrm{CP}$ and $\mathrm{CPT}$ invariance in hitherto unexplored dynamical situations.