Search for the K_S -> e+e- decay with the KLOE detector
  We present the result of a direct search for the decay K_S -> e+e-, obtained with a sample of e+e- -> phi -> K_S K_L events produced at DAFNE, the Frascati phi-factory, for an integrated luminosity of 1.9 fb^-1. The search has been performed using a pure K_S beam tagged by the simultaneous detection of a K_L interaction in the calorimeter. Background rejection has been optimized by using both kinematic and particle identification cuts. We find BR(K_S -> e+e-) < 9x10^-9 at 90% CL, which improves by an order of magnitude on the previous best limit. 
The KLOE Collaboration: F. Ambrosino, A. Antonelli, M. Antonelli, F.   Archilli, P. Beltrame, G. Bencivenni, S. Bertolucci, ...