ISSN - 03702693, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2014, vol. 731, p. 227-231
Measurement of the ratio of the lepton widths Γe e/Γμμ for the J/ψ meson
The ratio of the electron and muon widths of the J/ψ meson has been measured using direct J/ψ decays in the KEDR experiment at the VEPP-4M electron-positron collider. The result. Γe+e-(J/ψ)/Γμ+μ-(J/ψ)=1.0022±0.0044±0.0048(0.65%) is in good agreement with the lepton universality. The experience collected during this analysis will be used for J/ψ lepton width determination with up to 1% accuracy. © 2014 The Authors.