$K_{Le5}$ decay as a background in search for $K_L\to {\pi }^0{\mu }^{\pm }{e}^{\mp }$

Abstract

We consider a process $K_{Le5}(K_L\to {\pi }^0{\pi }^0{\pi }^{\pm }{e}^{\mp }\nu )$ as a standard model background to the experiment $K_L\to {\pi }^0{\mu }^{\pm }{e}^{\mp }$, which seeks for possible violation of lepton family number. Using the lowest order chiral lagrangian, we find that the branching ratio for $K_L\to {\pi }^0{\pi }^0{\pi }^{\pm }{e}^{\mp }\nu$ to be $6.2\times 10^{-12}$. A similar decay $K_L\to {\pi }^{\mp }{\pi }^{\mp }{\pi }^{\pm }{e}^{\pm }\nu$ has a branching ratio, $1.7\times 10^{-11}$.

Comments: RevTeX, 10 pages, 1 figure available upon request, to appear in Phys. Rev. D