The ration R=σ(e+e-→hadrons)/σ(e+e-→ μ+ μ-) was measured with the LENA detector at DORIS in a scan between 7.40 and 7.48 GeV and between 8.67 and 9.43 GeV center of mass energies. Corrected for QED radiative effects, R is found to be constant with an average value of R=3.37 ±0.06stat±0.23syst. No narrow resonances with Γee(Γhad/Γtot)⊗0.30 keV (95% C.L.) and no steps have been observed. Based on this value of R, revised values for υ(1S) resonance parameters are presented.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)