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Measurement of the Branching Fractions for J/psi to ell^+ ell^-

Z. Li·CLEO Collaboration
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Abstract

We present measurements of the branching fractions for J/psi --> e+e- and mu+mu- using 3M psi(2S) decays collected with the CLEO detector operating at the CESR e+e- collider. We obtain B(J/psi --> e+e-) = (5.945 +- 0.067 +- 0.042 )% and B(J/psi --> mu+mu-) = (5.960 +- 0.065 +- 0.050)%, leading to an average of B(J/psi --> l+l-) = (5.953 +- 0.056 +- 0.042)% and a ratio of B(J/psi --> e+e-) / B(J/psi --> mu+mu-) = (99.7 +- 1.2 +- 0.6)%, all consistent with, but more precise than, previous measurements.

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Z. Li, CLEO Collaboration. 2005-06-28. Measurement of the Branching Fractions for J/psi to ell^+ ell^-. https://doi.org/10.1103/physrevd.71.111103

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