Determination of Γ ee of the ϒ(1 S) and ϒ(2 S) resonances, and measurement of R at W = 9.46 GeV

Abstract

Using the Crystal Ball detector operating at the DORIS II storage ring we have measured the leptonic partial widths Γ ee of the ϒ(1 S) and ϒ(2 S) resonances. We discuss a consistent definition of Γ ee and show the effect on it by applying different prescriptions for radiative corrections. We also give a value of R, the ratio of non-resonant hadronic cross section to the Born cross section of μ pair production, at a c.m. energy of W = 9.46 GeV. All numerical results are preliminary.