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Observation of e+e- →ηY (2175) at center-of-mass energies above 3.7 GeV OBSERVATION of e+e- →ηY (2175) ... M. ABLIKIM et al.

Ablikim M., Achasov M. N., Ahmed S., Ai X. C., Albayrak O., Albrecht M., Ambrose D. J., Amoroso A., An F. F., An Q., Bai J. Z., Bakina O., Baldini Ferroli R., Ban Y., Bennett D. W., Bennett J. V., Berger N., Bertani M., Bettoni D., Bian J. M., Bianchi F., Boger E., Boyko I., Briere R. A., Cai H., Cai X., Cakir O., Calcaterra A., Cao G. F., Cetin S. A., Chai J., Chang J. F., Chelkov G., Chen G., Chen H. S., Chen J. C., Chen M. L., Chen S., Chen S. J., Chen X., Chen X. R., Chen Y. B., Chu X. K., Cibinetto G., Dai H. L., Dai J. P., Dbeyssi A., Dedovich D., Deng Z. Y., Denig A., Denysenko I., Destefanis M., De Mori F., Ding Y., Dong C., Dong J., Dong L. Y., Dong M. Y., Dou Z. L., Du S. X., Duan P. F., Fan J. Z., Fang J., Fang S. S., Fang Y., Farinelli R., Fava L., Feldbauer F., Felici G., Feng C. Q., Fioravanti E., Fritsch M.

© 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP 3 . The state Y(2175) is observed in the process e+e-→ηY(2175) with a statistical significance larger than 10 standard deviations using the data collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies between 3.7 and 4.6 GeV. This is the first observation of the Y(2175) in this process. The mass and width of the Y(2175) are determined to be (2135±8±9) MeV/c2 and (104±24±12) MeV, respectively, and the production cross section (σ) of e+e-→ηY(2175)→ηφf0(980)→ηφπ+π- is at the several hundred femtobarn level. No significant signal for the process e+e-→η′Y(2175) is observed and the upper limit on σ(e+e-→η′Y(2175))/σ(e+e-→ηY(2175)) is estimated to be 0.43 at the 90% confidence level. We also search for ψ(3686)→ηY(2175). No significant signal is observed, indicating a strong suppression relative to the corresponding J/ψ decay, in violation of the "12% rule".