Measurement ofR and determination of the charged-particle multiplicity ine + e − annihilation at 13-113-113-1around 10 GeV

We have measured theR value in non-resonante+e− annihilation using the ARGUS detector at the storage ring DORIS II. At a centre-of-mass energy\(\sqrt s = 9.36\) GeV the ratio of the hadronic cross-section to the μ-pair cross section in lowest order QED has been determined to beR=3.46±0.03±0.13. In addition, we have measured the charged-particle multiplicities in non-resonant hadron production at\(\sqrt s = 10.47\) GeV just below theB\(\bar B\) threshold and in ϒ (4S) resonance decays. For the average charged-particle multiplicities in continuum events and ϒ(4S)→B\(\bar B\) decays we obtain cont=8.35±0.02±0.20 and ϒ(4s)=10.81±0.05±0.23.