The spin and parity of the Zc(3900)± state are determined to be JP=1+ with a statistical significance larger than 7σ over other quantum numbers in a partial wave analysis of the process e+e-→π+π-J/ψ. We use a data sample of 1.92 fb-1 accumulated at s=4.23 and 4.26 GeV with the BESIII experiment. When parametrizing the Zc(3900)± with a Flatté-like formula, we determine its pole mass Mpole=(3881.2±4.2stat±52.7syst) MeV/c2 and pole width Γpole=(51.8±4.6stat±36.0syst) MeV. We also measure cross sections for the process e+e-→Zc(3900)+π-+c.c.→J/ψπ+π- and determine an upper limit at the 90% confidence level for the process e+e-→Zc(4020)+π-+c.c.→J/ψπ+π-.
Bibliographical noteFunding Information:
The BESIII Collaboration thanks the staff of BEPCII and the computing center for their strong support. This work is supported in part by the Ministry of Science and Technology of China under Contract No. 2009CB825200; Joint Funds of the National Natural Science Foundation of China under Contracts Nos. U1332201; National Natural Science Foundation of China (NSFC) under Contracts No. 11175188, No. 11375205, No. 11235011, No. 11375221, No. 11565006, and No. 10825524; German Research Foundation DFG under Collaborative Research Center Contract No. CRC-1044, 627240; Istituto Nazionale di Fisica Nucleare, Italy; Ministry of Development of Turkey under Contract No. DPT2006K-120470; U.S. Department of Energy under Contracts No. DE-SC-0012069, No. DE-SC-0010504, No. DE-SC-0010118, and No. DE-FG02-05ER41374; U.S. National Science Foundation; University of Groningen (RuG) under Contract No. 530-4CDP03, and the Helmholtzzentrum fuer Schwerionenforschung GmbH (GSI), Darmstadt; and WCU Program of National Research Foundation of Korea under Contract No. R32-2008-000-10155-0.
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