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M. Ablikim, М. Н. Ачасов, P. Adlarson, O. Afedulidis, X. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, I. Balossino, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Çetin, J. F. Chang, W. L. Chang, G. R., G. Chelkov, C. Chen, C. Chen, Chao Chen, G. Chen, Haifeng Chen, M. L. Chen, S. J. Chen, S. L. Chen, S. M. Chen, T. Chen, Xiaoyan Chen, X. T. Chen, Y. B. Chen, Y. Q. Chen, Z. J. Chen, Z. Y. Chen, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, C. Q. Deng, Z. Y. Deng, A. G. Denig, I. Denysenko, M. Destefanis, F. De Mori, B. Ding, X. X. Ding, Y. Ding, Y. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, M. C. Du, S. X. Du, Z. H. Duan, P. Egorov, Y. H. Fan, J. Fang, J. Fang, S. S. Fang, Wenxing Fang, Y. Fang, Y. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, Y. T. Feng, K. Fischer, M. Fritsch, C. D. Fu, J. Fu, Y. W. Fu, He Gao, Y. N. Gao
Abstract
Using data samples with an integrated luminosity of $5.85\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected at center-of-mass energies from 4.61 to 4.95 GeV with the BESIII detector operating at the BEPCII storage ring, we measure the cross section for the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}J/\ensuremath{\psi}$. A new resonance with a mass of $M=470{8}_{\ensuremath{-}15}^{+17}\ifmmode\pm\else\textpm\fi{}21\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ and a width of $\mathrm{\ensuremath{\Gamma}}=12{6}_{\ensuremath{-}23}^{+27}\ifmmode\pm\else\textpm\fi{}30\text{ }\text{ }\mathrm{MeV}$ is observed in the energy-dependent line shape of the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}J/\ensuremath{\psi}$ cross section with a significance over $5\ensuremath{\sigma}$. The ${K}^{+}J/\ensuremath{\psi}$ system is also investigated to search for charged charmoniumlike states, but no significant ${Z}_{cs}^{+}$ states are observed. Upper limits on the Born cross sections for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{Z}_{cs}(3985{)}^{+}/{K}^{\ensuremath{-}}{Z}_{cs}(4000{)}^{+}+c.c.$ with ${Z}_{cs}(3985{)}^{\ifmmode\pm\else\textpm\fi{}}/{Z}_{cs}(4000{)}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{K}^{\ifmmode\pm\else\textpm\fi{}}J/\ensuremath{\psi}$ are reported at 90% confidence levels. The ratio of branching fractions ${[\mathcal{B}({Z}_{cs}(3985{)}^{+}\ensuremath{\rightarrow}{K}^{+}J/\ensuremath{\psi})]/\mathcal{B}[{Z}_{cs}(3985{)}^{+}\ensuremath{\rightarrow}({\overline{D}}^{0}{D}_{s}^{*+}+{\overline{D}}^{*0}{D}_{s}^{+})]}$ is measured to be less than 0.03 at 90% confidence level.