New R Values in 2-5 Gev from the Beijing Spectrometer

G. S. Huang, representing the BES Collaboration

The values of $R=\sigma (e^{+}{e}^{-}\to hadrons)/\sigma (e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-})$ for 85 center-of-mass energies between 2 and 5 GeV were measured with the upgraded Beijing Spectrometer at the Beijing…