ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2012, vol. 86, p. -
Observation of e +e -→ηJ/ψ at center-of-mass energy √s=4.009GeV
Using a 478pb -1 data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider storage ring at a center-of-mass energy of √s=4.009GeV, the production of e +e -→ηJ/ψ is observed for the first time with a statistical significance of greater than 10σ. The Born cross section is measured to be (32.1±2.8±1.3)pb, where the first error is statistical and the second systematic. Assuming the ηJ/ψ signal is from a hadronic transition of the ψ(4040), the fractional transition rate is determined to be B(ψ(4040)→ηJ/ψ)=(5.2±0.5±0. 2±0.5)×10 -3, where the first, second, and third errors are statistical, systematic, and the uncertainty from the ψ(4040) resonant parameters, respectively. The production of e +e -→π0J/ψ is searched for, but no significant signal is observed, and B(ψ(4040)→π0J/ψ)<2.8×10 -4 is obtained at the 90% confidence level. © 2012 American Physical Society.