Measurement of the branching fractions for ψ(2s)→e+e- and ψ(2s)→μ+μ-

Abstract

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+π-. The method uses ψ(2S) mesons produced in the decay of B mesons at the Υ(4S) 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 μ+μ- branching fractions to be 0.0078±0.0009±0.0008 and 0.0067±0.0008±0.0007, respectively