ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2002, vol. 65, p. -
Measurement of the branching fractions for Ψ(2S)→e +e - and Ψ(2S)→μ +-
We measure the branching fractions of the Ψ(2S) meson to the leptonic final states e +e - and μ +μ - relative to that for Ψ(2S)→J/Ψπ _. The method uses Ψ(2S) mesons produced in the decay of B mesons at the Y(45) resonance in a data sample collected with the BABAR detector at the Stanford Linear Accelerator Center. Using previous measurements for the Ψ(2S) →J/Ψπ +π - branching fraction, we determine the e +e - and π +π - branching fractions to be 0.0078±0.0009±0.0008 and 0.0067±0. 0008±0.0007, respectively. © 2001 The American Physical Society.