Abstract
We analyze K L lepton pair decays of K L →l + l - γ and K L →l + l - l′ - (l, l′ = e, μ) within the framework of the light-front QCD approach (LFQA). With the K L →γ *γ* form factors evaluated in a model with the LFQA, we calculate the decay branching ratios and find that our results are all consistent with the experimental data. In addition, we study K L →l + l - decays. We point out that our prediction for K L e + e - is about 20% smaller than that in chiral perturbation theory. We also discuss whether one could extract the short-distance physics from K L →μ + μ - . © 2002 The American Physical Society.