ISSN - 03702693, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2015, vol. 761, p. 98-103
Measurement of the leptonic decay width of J/ψ using initial state radiation
© 2016 The Author(s).Using a data set of 2.93 fb−1 taken at a center-of-mass energy of √s = 3.773 GeVwith the BESIII detector at the BEPCII collider, we measure the process e+e− → J/ψγ →μ+μ−γ and determine the product of the branching fraction and the electronic width Bμμ · Γee = (333.4 ± 2.5stat ± 4.4sys) eV. Using the earlier-published BESIII result for Bμμ = (5.973 ± 0.007stat ± 0.037sys)%, we derive the J/ψ electronic width Γee = (5.58 ±0.05stat ±0.08sys) keV.