Measurement of the branching ratio of pi(0) -> e(+)e(-) using K-L -> 3 pi(0) decays in flight

Citation
A. Alavi-harati et al., Measurement of the branching ratio of pi(0) -> e(+)e(-) using K-L -> 3 pi(0) decays in flight, PHYS REV L, 83(5), 1999, pp. 922-925
Citations number
16
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
PHYSICAL REVIEW LETTERS
ISSN journal
0031-9007 → ACNP
Volume
83
Issue
5
Year of publication
1999
Pages
922 - 925
Database
ISI
SICI code
0031-9007(19990802)83:5<922:MOTBRO>2.0.ZU;2-Y
Abstract
The branching ratio of the rare decay pi(0) --> e(+)e(-) has been measured in E799-II, a rare kaon decay experiment using the KTeV detector at Fermila b. We observed 275 candidate pi(0) --> e(+)e(-) events, with an expected ba ckground of 21.4 +/- 6.2 events which includes the contribution from Dalitz decays. We measured B[pi(0) --> e(+)e(-), (m(e+e-)/m(pi 0))(2) > 0.95] = ( 6.09 +/- 0.40 +/- 0.24) X 10(-8), where the first error is statistical and the second systematic. This result is the first significant observation of the excess rate for this decay above the unitarity lower bound.