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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

Ablikim M., Achasov M. N., Ambrose D. J., An F. F., An Q., An Z. H., Bai J. Z., Ban Y., Becker J., Bennett J. V., Bertani M., Bian J. M., Boger E., Bondarenko O., Boyko I., Briere R. A., Bytev V., Cai X., Cakir O., Calcaterra A., Cao G. F., Cetin S. A., Chang J. F., Chelkov G., Chen G., Chen H. S., Chen J. C., Chen M. L., Chen S. J., Chen Y. B., Cheng H. P., Chu Y. P., Cronin-Hennessy D., Dai H. L., Dai J. P., Dedovich D., Deng Z. Y., Denig A., Denysenko I., Destefanis M., Ding W. M., Ding Y., Dong L. Y., Dong M. Y., Du S. X., Fang J., Fang S. S., Fava L., Feldbauer F., Feng C. Q., Ferroli R. B., Fu C. D., Fu J. L., Gao Y., Geng C., Goetzen K., Gong W. X., Gradl W., Greco M., Gu M. H., Gu Y. T., Guan Y. H., Guo A. Q., Guo L. B., Guo Y. P., Han Y. L., Harris F. A., He K. L., He M., He Z. Y., Held T., Heng Y. K., Hou Z. L., Hu H. M., Hu J. F., Hu T., Huang G. M., Huang J. S., Huang X. T., Huang Y. P., Hussain T., Ji C. S., Ji Q., Ji X. B., Ji X. L., Jiang L. L., Jiang X. S., Jiao J. B., Jiao Z., Jin D. P., Jin S., Jing F. F., Kalantar-Nayestanaki N., Kavatsyuk M., Kuehn W.

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.