Study of the process <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mo stretchy="false">→</mml:mo><mml:mi>ϕ</mml:mi><mml:mi>η</mml:mi></mml:math> at center-of-mass energies between 2.00 and 3.08 GeV
M. Ablikim, М. Н. Ачасов, P. Adlarson, S. Ahmed, M. Albrecht, R. Aliberti, A. Amoroso, M. R. An, Q. An, X. H. Bai, Y. Bai, O. Bakina, R. Baldini Ferroli, I. Balossino, Y. Ban, K. Begzsuren, N. Berger, M. Bertani, D. Bettoni, F. Bianchi, J. Bloms, A. Bortone, I. Boyko, R. A. Briere, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Çetin, J. F. Chang, W. L. Chang, G. Chelkov, D. Y. Chen, G. Chen, He Chen, M. L. Chen, S. J. Chen, X. R. Chen, Y. B. Chen, Z. J. Chen, W. S. Cheng, G. Cibinetto, F. Cossio, X. F. Cui, H. L. Dai, X. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, Y. Ding, C. Dong, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, S. X. Du, Y. L. Fan, J. Fang, S. S. Fang, Y. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, M. Fritsch, C. D. Fu, X. L. Gao, Y. Gao, Y. Gao, Y. Gao, Y. Gao, I. Garzia, P. T. Ge, Chao Geng, E. Gersabeck, A. Gilman, K. Goetzen, L. Gong, W. X. Gong, W. Gradl, M. Greco, L. Gu, M. H. Gu, Y. T. Gu, C. Y. Guan, A. Q. Guo, L. B. Guo, R. P. Guo, Y. P. Guo, A. Guskov, T. T. Han, W. Y. Han
Abstract
The process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\phi}\ensuremath{\eta}$ is studied at 22 center-of-mass energy points ($\sqrt{s}$) between 2.00 and 3.08 GeV using $715\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected with the BESIII detector. The measured Born cross section of ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\phi}\ensuremath{\eta}$ is found to be consistent with BABAR measurements, but with improved precision. A resonant structure around 2.175 GeV is observed with a significance of $6.9\ensuremath{\sigma}$ with mass $(2163.5\ifmmode\pm\else\textpm\fi{}6.2\ifmmode\pm\else\textpm\fi{}3.0)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ and width $({31.1}_{\ensuremath{-}11.6}^{+21.1}\ifmmode\pm\else\textpm\fi{}1.1)\text{ }\text{ }\mathrm{MeV}$, where the first uncertainties are statistical and the second are systematic.