Search for the KS→ e+e- decay with the KLOE detector at da PdblNE

We present results of a direct search for the decay KS → e +e- with the KLOE de- tector, obtained with a sample of e+e- → φ → KSKL events produced at DAPdblNE, the Frascati φ-factory, for an integrated luminosity of 1.3 fb-1. The StandardModel prediction for this decay is BR(KS → e+e -) = 1.6 × 10-15. The search has been performed tagging the KS decays by simultaneous detection of a KL interaction in the calorimeter. Background rejection has been optimized by using both kine- matic cuts and particle identification. At the end of the analysis chain we find BR(KS → e+e-) < 2.1 × 10-8 at 90% CL, which improves by a factor of ∼ 7 on the previous best result, obtained by CPLEAR experiment.