Decoding the Riddle ofY(4260)andZc(3900)

• DOI: 10.1103/physrevlett.111.132003
• Publication Date: 2013-09-26T14:48:18Z
• Authors: Qian Wang; Christoph Hanhart; Qiang Zhao
• Keywords: Isovector; Invariant mass

The observation of $Z_c(3900)$ by the BESIII collaboration in invariant mass spectrum $J/\psi\pi^\pm$ $e^+e^-\to J/\psi\pi^+\pi^-$ at center 4.260 GeV suggests existence a charged $\bar D D^*+D\bar D^*$ molecular state with $I(J^P)=1(1^+)$, which could be an isovector brother famous X(3872) and analogue $Z_b(10610)$ claimed Belle Collaboration. We demonstrate that this provides strong evidence mysterious Y(4260) is $\bar{D}D_1(2420) +D\bar{D}_1(2420)$ state. Especially, we show decay molecule naturally populates low momentum DD^*$ pairs leads unavoidably to cusp threshold. discuss signatures distinguish such from presence true resonance.