Search for the KS-->e+e- decay with the KLOE detector at DAPHNE

Ambrosino, Fabio; Antonelli, A.; Antonelli, M.; Archilli, F.; Bacci, C.; Beltrame, P.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocchetta, S.; Bocci, V.; Bossi, F.; Branchini, P.; Caloi, R.; Campana, P.; Capon, G.; Capussela, Tiziana; Ceradini, F.; Chi, S.; Chiefari, G.; Ciambrone, P.; Lucia, E. D.; Santis, A. D.; Simone, P. D.; Zorzi, G. D.; Denig, A.; Domenico, A. D.; Donato, C. D.; Falco, S. D.; Micco, B. D.; Doria, A.; Dreucci, M.; Felici, G.; Ferrari, A.; Ferrer, M. L.; Finocchiaro, G.; Fiore, S.; Forti, C.; Franzini, P.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Gorini, E.; Graziani, E.; Incagli, M.; Kluge, W.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee Franzini, J. I.; Leone, D.; Martini, M.; Massarotti, Paolo; Mei, W.; Meola, S.; Miscetti, S.; Moulson, M.; M??????ller, S.; Murtas, F.; Napolitano, M.; Nguyen, F.; Palutan, M. B.; Pasqualucci, E.; Passeri, A.; Patera, V. F.; Perfetto, F.; Primavera, M.; Santangelo, P.; Saracino, Giulio; Sciascia, B.; Sciubba, A. F.; Scuri, F.; Sfiligoi, I.; Spadaro, T.; Testa, M.; Tortora, L.; Valente, P.; Valeriani, B.; Venanzoni, G.; Versaci, R.; G. J., Xu

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.

Search for the KS-->e+e- decay with the KLOE detector at DAPHNE / Ambrosino, F., A., A., M., A., F., A., C., B., P., B., G., B., S., B., C., B., C., B., S., B., V., B., F., B., P., B., R., C., P., C., G., C., Capussela, T., F., C., S., C., et al.. - (2007). (23rd International Symposium on Lepton-Photon Interactions at High Energy, LP 2007 2007).