Phys. Rev. D 75, 012004 (2007) [6 pages]Measurement of the rare decay π0→e+e-Received 24 October 2006; published 11 January 2007 The branching ratio of the rare decay π0→e+e- has been measured precisely, using the complete data set from the KTeV E799-II experiment at Fermilab. We observe 794 candidate π0→e+e- events using KL→3π0 as a source of tagged π0s. The expected background is 52.7±11.2 events, predominantly from high e+e- mass π0→e+e-γ decays. We have measured B(π0→e+e-,(me+e-/mπ0)2>0.95)=(6.44±0.25stat±0.22syst)×10-8, which is above the unitary bound from π0→γγ and within the range of theoretical expectations from the standard model. © 2007 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevD.75.012004
DOI:
10.1103/PhysRevD.75.012004
PACS:
13.25.Cq
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