Measurement of the branching fractions for J/psi ---> l+ l-

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.

13.20.Gd
14.40.Gx
electron positron: colliding beams
electron positron: annihilation
psi(3685): electroproduction
psi(3685): hadronic decay
J/psi(3100): leptonic decay
electron: pair production
muon: pair production
J/psi(3100): branching ratio

References(14)

Figures(0)

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