Download or read book Measuring the Branching Ratio of the Rare Decay ?0{u2192}e+e-. written by and published by . This book was released on 2006 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: A precise branching ratio measurement of the rare decay ?0→e+e- has been made. The measurement was made with the rare kaon decay experiment KTeV at Fermilab where the source of ?0s was KL → ?0?0?0 decaying in flight. A total of 794 fully reconstructed KL → 3?0 events consistent with two of the intermediate ?0s decaying into ?? and one into e+e- were collected. An estimated 53.2 ± 11.0 of these events were expected to be background. Normalizing to the ?0 Dalitz decay they found Br(?0 → e+e-, (me+e-/m ?0)2 > 0.95) = (6.44 ± 0.25(stat) ± 0.22(syst)) x 10-8 where internal radiation, ?0 → e+e-(?), was limited by the requirement (me+e-/m?0)2 > 0.95 which separated it from the tree level Dalitz decay, ?0 → e+e-?.