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Observation of a Charged<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>D</mml:mi><mml:msup><mml:mrow><mml:mover accent="true"><mml:mrow><mml:mi>D</mml:mi></mml:mrow><mml:mrow><mml:mo stretchy="false">¯</mml:mo></mml:mrow></mml:mover></mml:mrow><mml:mrow><mml:mo>*</mml:mo></mml:mrow></mml:msup><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mrow><mml:mo>±</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>Mass Peak in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup><mml:mo>→</mml:mo><mml:mi>π</mml:mi><mml:mi>D</mml:mi><mml:msup><mml:mrow><mml:mover accent="true"><mml:mrow><mml:mi>D</mml:mi></mml:mrow><mml:mrow><mml:mo stretchy="false">¯</mml:mo></mml:mrow></mml:mover></mml:mrow><mml:mrow><mml:mo>*</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msqrt><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:msqrt><mml:mo>=</mml:mo><mml:mn>4.26</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>GeV</mml:mi></mml:mrow></mml:math>

M. AblikimInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaM. N. AchasovG.I. Budker Institute of Nuclear Physics SB RAS (BINP), Novosibirsk 630090, RussiaO. AlbayrakCarnegie Mellon University, Pittsburgh, Pennsylvania 15213, USAD. AmbroseUniversity of Rochester, Rochester, New York 14627, USAF. F. AnInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaQ. AnUniversity of Science and Technology of China, Hefei 230026, People's Republic of ChinaJ.Z. BaiInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaR. Baldini FerroliINFN Laboratori Nazionali di Frascati, I-00044, Frascati, ItalyY. BanPeking University, Beijing 100871, People's Republic of ChinaJürgen BeckerBochum Ruhr-University, D-44780 Bochum, GermanyJ. V. BennettIndiana University, Bloomington, Indiana 47405, USAM. BertaniINFN Laboratori Nazionali di Frascati, I-00044, Frascati, ItalyJ. M. BianUniversity of Minnesota, Minneapolis, Minnesota 55455, USAE. BogerJoint Institute for Nuclear Research, 141980 Dubna, Moscow region, RussiaO. BondarenkoKVI, University of Groningen, NL-9747 AA Groningen, NetherlandsI. BoykoJoint Institute for Nuclear Research, 141980 Dubna, Moscow region, RussiaS. BraunR. A. BriereCarnegie Mellon University, Pittsburgh, Pennsylvania 15213, USAV. BytevJoint Institute for Nuclear Research, 141980 Dubna, Moscow region, RussiaH. CaiWuhanUniversity, Wuhan 430072, People's Republic of ChinaX. Z. CaiInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaÖ. ÇakırAnkara University, Dogol Caddesi, 06100 Tandogan, Ankara, TurkeyA. CalcaterraINFN Laboratori Nazionali di Frascati, I-00044, Frascati, ItalyG. F. CaoInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaS. A. ÇetinDogus University, 34722 Istanbul, TurkeyJ. F. ChangInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaG. ChelkovJoint Institute for Nuclear Research, 141980 Dubna, Moscow region, RussiaG. ChenInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaH. S. ChenInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaJ. C. ChenInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaM. L. ChenInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaS. ChenNanjing University, Nanjing 210093, People's Republic of ChinaX. R. ChenLanzhou University, Lanzhou 730000, People's Republic of ChinaY. B. ChenInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaH. P. ChengHuangshan College, Huangshan 245000, People's Republic of ChinaX. ChuPeking University, Beijing 100871, People's Republic of ChinaY. P. ChuInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaD. Cronin-HennessyUniversity of Minnesota, Minneapolis, Minnesota 55455, USAH. L. DaiInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaJ. P. DaiInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaD. DedovichJoint Institute for Nuclear Research, 141980 Dubna, Moscow region, RussiaZ. Y. DengInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaA. DenigJohannes Gutenberg University of Mainz, Johann-Joachim-Becher-Weg 45, D-55099 Mainz, GermanyI. DenysenkoJoint Institute for Nuclear Research, 141980 Dubna, Moscow region, RussiaM. DestefanisUniversity of Turin, I-10125 Turin, Italy and INFN, I-10125 Turin, ItalyW. M. DingShandong University, Jinan 250100, People's Republic of ChinaY. DingLiaoning University, Shenyang 110036, People's Republic of ChinaL. Y. DongInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaM. Y. DongInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaS. X. DuZhengzhou University, Zhengzhou 450001, People's Republic of ChinaJ. FangInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaS. S. FangInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaL. FavaUniversity of Eastern Piedmont, I-15121 Alessandria, Italy and INFN, I-10125 Turin, ItalyChunsheng FengUniversity of Science and Technology of China, Hefei 230026, People's Republic of ChinaP. FriedelBochum Ruhr-University, D-44780 Bochum, GermanyC. D. FuInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaJ. FuNanjing University, Nanjing 210093, People's Republic of ChinaYang GaoTsinghua University, Beijing 100084, People's Republic of ChinaC. GengUniversity of Science and Technology of China, Hefei 230026, People's Republic of ChinaK. GoetzenGSI Helmholtzcentre for Heavy Ion Research GmbH, D-64291 Darmstadt, GermanyW. X. GongInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaW. GradlJohannes Gutenberg University of Mainz, Johann-Joachim-Becher-Weg 45, D-55099 Mainz, GermanyM. GrecoUniversity of Turin, I-10125 Turin, Italy and INFN, I-10125 Turin, ItalyM. H. GuInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaY. T. GuGuangXi University, Nanning 530004, People's Republic of ChinaY. H. GuanUniversity of Chinese Academy of Sciences, Beijing 100049, People's Republic of ChinaA. Q. GuoNankai University, Tianjin 300071, People's Republic of ChinaL. B. GuoNanjing Normal University, Nanjing 210023, People's Republic of ChinaTingting GuoNanjing Normal University, Nanjing 210023, People's Republic of ChinaY. P. GuoNankai University, Tianjin 300071, People's Republic of ChinaY. L. HanInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaF. A. HarrisUniversity of Hawaii, Honolulu, Hawaii 96822, USAK. L. HeInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaM. HeInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaZ. Y. HeNankai University, Tianjin 300071, People's Republic of ChinaT. HeldBochum Ruhr-University, D-44780 Bochum, GermanyY. K. HengInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaZ. L. HouInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaChenguo HuNanjing Normal University, Nanjing 210023, People's Republic of ChinaH. M. HuInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaJ. F. HuT. HuInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaG. M. HuangCentral China Normal University, Wuhan 430079, People's Republic of ChinaG. S. HuangCentral China Normal University, Wuhan 430079, People's Republic of ChinaJ. S. HuangHenan Normal University, Xinxiang 453007, People's Republic of ChinaL. HuangInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaX. T. HuangShandong University, Jinan 250100, People's Republic of ChinaYin HuangNanjing University, Nanjing 210093, People's Republic of ChinaT. HussainUniversity of the Punjab, Lahore-54590, PakistanC. S. JiUniversity of Science and Technology of China, Hefei 230026, People's Republic of ChinaQ. P. JiInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaQ. P. JiInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaX. B. JiInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaX. L. JiInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaL. L. JiangInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaX. S. JiangInstitute of High Energy Physics, Beijing 100049, People's Republic of ChinaJ. B. JiaoShandong University, Jinan 250100, People's Republic of ChinaZ. JiaoHuangshan College, Huangshan 245000, People's Republic of ChinaD. P. JinInstitute of High Energy Physics, Beijing 100049, People's Republic of China
2014lv
ABI

Abstract

We report on a study of the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{(D{\overline{D}}^{*})}^{\ensuremath{\mp}}$ at $\sqrt{s}=4.26\text{ }\text{ }\mathrm{GeV}$ using a $525\text{ }\mathrm{pb}{}^{\ensuremath{-}1}$ data sample collected with the BESIII detector at the BEPCII storage ring. A distinct charged structure is observed in the ${(D{\overline{D}}^{*})}^{\ensuremath{\mp}}$ invariant mass distribution. When fitted to a mass-dependent-width Breit-Wigner line shape, the pole mass and width are determined to be ${M}_{\mathrm{pole}}=\phantom{\rule{0ex}{0ex}}\mathbf{(}3883.9\ifmmode\pm\else\textpm\fi{}1.5\phantom{\rule{0.333em}{0ex}}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}4.2\phantom{\rule{0.333em}{0ex}}(\mathrm{syst})\mathbf{)}\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ and ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{pole}}=\mathbf{(}24.8\ifmmode\pm\else\textpm\fi{}3.3\phantom{\rule{0.333em}{0ex}}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}11.0\phantom{\rule{0.333em}{0ex}}(\mathrm{syst})\mathbf{)}\text{ }\text{ }\mathrm{MeV}$. The mass and width of the structure, which we refer to as ${Z}_{c}(3885)$, are $2\ensuremath{\sigma}$ and $1\ensuremath{\sigma}$, respectively, below those of the ${Z}_{c}(3900)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}J/\ensuremath{\psi}$ peak observed by BESIII and Belle in ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}J/\ensuremath{\psi}$ final states produced at the same center-of-mass energy. The angular distribution of the $\ensuremath{\pi}{Z}_{c}(3885)$ system favors a ${J}^{P}={1}^{+}$ quantum number assignment for the structure and disfavors ${1}^{\ensuremath{-}}$ or ${0}^{\ensuremath{-}}$. The Born cross section times the $D{\overline{D}}^{*}$ branching fraction of the ${Z}_{c}(3885)$ is measured to be ${\ensuremath{\sigma}\mathbf{(}{e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\phantom{\rule{0ex}{0ex}}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{Z}_{c}(3885)}^{\ensuremath{\mp}}\mathbf{)}\ifmmode\times\else\texttimes\fi{}{\mathcal{B}\mathbf{(}{Z}_{c}(3885)}^{\ensuremath{\mp}}\ensuremath{\rightarrow}{(D{\overline{D}}^{*})}^{\ensuremath{\mp}}\mathbf{)}=\mathbf{(}83.5\ifmmode\pm\else\textpm\fi{}6.6\phantom{\rule{0.333em}{0ex}}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}22.0\phantom{\rule{0.333em}{0ex}}(\mathrm{syst})\mathbf{)}\text{ }\text{ }\text{ }\mathrm{pb}$. Assuming the ${Z}_{c}(3885)\ensuremath{\rightarrow}D{\overline{D}}^{*}$ signal reported here and the ${Z}_{c}(3900)\ensuremath{\rightarrow}\ensuremath{\pi}J/\ensuremath{\psi}$ signal are from the same source, the partial width ratio $(\mathrm{\ensuremath{\Gamma}}({Z}_{c}(3885)\ensuremath{\rightarrow}D{\overline{D}}^{*})/\mathrm{\ensuremath{\Gamma}}({Z}_{c}(3900)\ensuremath{\rightarrow}\ensuremath{\pi}J/\ensuremath{\psi}))=6.2\ifmmode\pm\else\textpm\fi{}1.1\phantom{\rule{0.333em}{0ex}}(\mathrm{stat})\phantom{\rule{0.333em}{0ex}}\ifmmode\pm\else\textpm\fi{}2.7\phantom{\rule{0.333em}{0ex}}(\mathrm{syst})$ is determined.

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