Author/Authors :
BES Collaboration، نويسنده , , Guang-Pei Chen، نويسنده ,
Abstract :
By using the upgraded Beijing Spectrometer (BESII), the total cross section for e+e− annihilation into hadronic final states at center-of-mass energies between 2 to 5 GeV are measured. Values of R at 2.6, 3.2, 3.4, 3.55, 4.6 and 5.0 GeV are determined, preliminary results for part of the successive points are also presented.
