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Observation of the π0 → e+e− decay |
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| Authors: | J. Fischer P. Extermann O. Guisan R. Mermod B. Morel L. Rosselet R. Sachot P. Bloch G. Bunce B. Devaux A.M. Diamant-Berger N. Do-Duc G. Marel R. Turlay |
| Affiliation: | University of Geneva, Switzerland;Département de Physique des Particules Elémentaires, Centre d''Etudes Nucléaires, Saclay, France |
| Abstract: | We have observed for the first time the very rare π0 → e+e? decay. The tagged π0's come from K+ → π+π0 decays in flight. We find the branching ratio to be (2.23?1.1+2.4) × 10?7 (90% C.L.). This value is well above the QED unitary limit and comes in rough agreement with a second-order electromagnetic process mediated by vector mesons. |
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