Determination of the electronic branching ratio of the ϒ(9.46) and an upper limit for its total width

Abstract We have measured the reaction e + e − → e + e − at the ϒ Using athe excess of electron pairs over the QED expectation we obtain an electronic branching ratio of B ee = (5.1 ± 3.0) %. Combining this with publishe values of the muonic branching ratio B μμ we conclude that the ϒ is a narrow state with a total width