Author: Amitabh Lath
Title: Rare Decays of K L and _0to Leptons.
Abstract: We present preliminary branching ratio measurements of the rare decays _0! 2e, _0! 4e,KL ! 4e as well as a signi_cant observation of KL ! e-e_+__from data taken during the 1997 run of KTeV/E799II. These decays probe the_ _form factor of the _0 and KL. The KL_ _form factor is useful in understanding the long-distance contribution to the decay KL ! _+__. Our measurement of the _0 ! 2e branching ratio constitutes the _rst signi_cant measurement ofthe excess over the QED unitarity limit. All these analyses represent at least an order of magni-tude increase in statistics over previously published results. In the case of KL ! e+e__+__, our observations solidify the previous observation (made by E799I), which was based on one event.
Comments: For the KTeV Collaboration, Rutgers University