We have observed 72915 KL0e() decays in the data set collected in the 19871988 run of Fermilab experiment E731. We found the Ke4 branching ratio to be [5.160.20(stat)0.22(sys)]×10-5. We also performed the first measurement of the form factors parametrizing the decay. Our branching ratio result agrees with a prediction using a vector-meson-exchange model. An interpretation of the data in terms of chiral perturbation theory implies a value L3=(3.40.4) ×10-3 in the O(p4) chiral Lagrangian.
ASJC Scopus subject areas
- Physics and Astronomy(all)