MEASUREMENT OF THE BRANCHING FRACTIONS FOR PSI(2S) ---> E+ E- AND PSI(2S) ---> MU+ MU-

The authors measure the branching fractions of the {psi}(2S) meson to the leptonic final states e{sup +}e{sup -} and {mu}{sup +}{mu}{sup -} relative to that for {psi}(2S) {yields} J/{psi} {pi}{sup +}{pi}{sup -}. The method uses {psi}(2S) mesons produced in the decay of B mesons at the {Upsilon}(4S) resonance in a data sample collected with the BABAR detector at the Stanford Linear Accelerator Center. Using previous measurements for the {psi}(2S) {yields} J/{psi} {pi}{sup +}{pi}{sup -} branching fraction, they determine the e{sup +}e{sup -} and {mu}{sup +}{mu}{sup -} branching fractions to be 0.0078 {+-} 0.0009 {+-} 0.0008 and 0.0067 {+-} 0.0008 {+-} 0.0007 respectively.