Fermion Loops and theK20→μ+μ−Puzzle

Abstract

We show that the fermion-loop model for $K_2^0\to \gamma \gamma$ recently proposed by Rockmore and Wong makes the puzzle of the missing $K_2^0\to {\mu }^{+}{\mu }^{-}$ rate some four times worse, and that the difficulty cannot be removed by the usual $\mathrm{CP}$-violation hypothesis.