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ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2014, vol. 112, p. -

Observation of a charged (D D ̄ *) ± mass peak in e + e - → π D D ̄ * at s = 4.26 GeV

Ablikim M., Achasov M. N., Albayrak O., Ambrose D. J., An F. F., An Q., Bai J. Z., Baldini Ferroli R., Ban Y., Becker J., Bennett J. V., Bertani M., Bian J. M., Boger E., Bondarenko O., Boyko I., Braun S., Briere R. A., Bytev V., Cai H., 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 X. R., Chen Y. B., Cheng H. P., Chu X. K., 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., Feng C. Q., Friedel P., Fu C. D., Fu J. L., Fuks O., 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 T., 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 C., Hu H. M., Hu J. F., Hu T., Huang G. M., Huang G. S., Huang J. S., Huang L., Huang X. T., Huang Y., Hussain T., Ji C. S., Ji Q., Ji Q. P., Ji X. B., Ji X. L., Jiang L. L., Jiang X. S.

We report on a study of the process e+e-→π±(DD̄*) - at s=4.26 GeV using a 525 pb-1 data sample collected with the BESIII detector at the BEPCII storage ring. A distinct charged structure is observed in the (DD̄*)- invariant mass distribution. When fitted to a mass-dependent-width Breit-Wigner line shape, the pole mass and width are determined to be Mpole=(3883.9±1.5(stat)±4.2(syst)) MeV/c2 and Γpole=(24.8±3.3(stat)±11.0(syst)) MeV. The mass and width of the structure, which we refer to as Zc(3885), are 2σ and 1σ, respectively, below those of the Zc(3900)→π±J/ψ peak observed by BESIII and Belle in π+π-J/ψ final states produced at the same center-of-mass energy. The angular distribution of the πZc(3885) system favors a JP=1+ quantum number assignment for the structure and disfavors 1- or 0-. The Born cross section times the DD̄* branching fraction of the Zc(3885) is measured to be σ(e+e-→π±Zc(3885)-) ×B(Zc(3885)- →(DD̄*)-)=(83.5±6.6(stat)±22. 0(syst)) pb. Assuming the Zc(3885)→DD̄* signal reported here and the Zc(3900)→πJ/ψ signal are from the same source, the partial width ratio (Γ(Zc(3885)→DD̄*)/Γ(Zc(3900)→πJ/ ψ))=6.2±1.1(stat)±2.7(syst) is determined. © 2014 American Physical Society.