Observation of e(+)e(-)→π(0)π(0)hc and a neutral charmoniumlike structure Zc(4020)(0).

M Ablikim,M Leyhe,K Zhu,I Denysenko,I Uman,W Wang,M Wang,L Fava,V Santoro,M Lv,A Calcaterra,S Spataro,T Li,B Wang,Y Zeng,M Lara,G Cibinetto,S Schumann,K Peters,T Johansson,A Denig,W Shan,H Loehner,B Zhong,A Sarantsev,T Hu,F Bianchi,Q An,S Nisar,M Shao,P Larin,M Ripka,X Cai,U Wiedner,S Han,M Greco,Feng Liu,Z Xue,G Chelkov,C Zhang,J Dong,S Sosio,Y Zhang,O Bondarenko,T Held,G Li,B Zheng,W Gradl,D Dedovich,G Felici,I Garzia,C Morales Morales,S Pacetti,Z Jiao,G Zhao,H Muramatsu,Zhiqiang Liu,K Goetzen,H Ye,M Wolke,S Marcello,A Amoroso,R Baldini Ferroli,L Yang,M Pelizaeus,D Toth,Z Ning,Y Nefedov,K Zhang,T Luo,K Schoenning,A Zhemchugov,D Wang,Y Hu,Q Zhao,G Rong,Fang Liu,H Moeini,M Qi,J Zhuang,F Nerling,Q Gao,D Cronin-Hennessy,B Kopf,C Dong,Z Haddadi,R Kliemt,F Feldbauer,F Li,G Chen,M Destefanis,P Wang,O Albayrak,Y Fang,T Hussain,A Yuncu,S Jin,L Yan,X Liu,M Albrecht,Y Ban,Li Zhou,K Liu,M Savrié,M Ullrich,Y Huang,Y Yuan,Cheng Li,Q Ji,Q Ouyang,J Liu,B Spruck,Jin Li,J Fang,K Li,K Moriya,E Boger,M Kornicer,Zhiqing Liu,Y Ding,M Bertani,D Bettoni,S Ma,M Tiemens,P Weidenkaff,H Cai,X Tang,A Hafner,W Lai,M Kavatsyuk,E Fioravanti,H Liang,A Julin,Z Wu,X Chen,Y Xia,Y Lu,Ling Zhao,A Zallo,B Kloss,Z Wang,I Tapan,K Wang,N Yu Muchnoi,F De Mori,M Maggiora,M Ye,Q Liu,D Xiao,L Zhang,W Kuehn,R Poling,J Min,X L Luo ,Y D Wang ,X B Ji ,J L Ping ,H B Li ,M X Luo ,J Y Zhao ,A Q Guo ,D H Wei ,Z H Zhang ,M H Gu ,X D Ruan ,Qin Liu ,Tao Ma ,Z B Li ,Z L Hou ,G Varner ,W C Yan ,P L Wang ,Q J Li ,W D Li ,L L Jiang ,S S Sun ,J Z Zhang ,F A Harris ,X Y Shen ,X P Xu ,S S Fang ,Z Y Deng ,Z P Mao ,J G Lu ,X S Qin ,F C ,S A Çetin ,X T Huang ,W M Song ,R Q Lu ,X X Liu ,Dong Liu ,X Ai ,O B Kolcu ,L Xia ,H H Zhang ,Y T Liang ,Z A Zhu ,J Y Zhang ,X N ,A A Zafar ,Hongxia Huang ,X Y Song ,Y B Liu ,H M Liu ,L L Wang ,Y Q Wang ,S G Wang ,F E Maas ,C X Yu ,Z G Wang ,J M Bian ,I B Nikolaev ,X Y Zhang ,W G Li ,Z J Xiao ,Yifan Yang ,Z Y Zhang ,Z G Zhao ,T J Min ,H Ren ,X M Li ,J F Hu ,B X Yu ,X L Ji ,S J Chen ,J S Huang ,X K Zhou ,H P Cheng ,I R Boyko ,Y P Lu ,J V Bennett ,Y B Chen ,H T Zhang ,Xiaoyu Zhu ,W L Yuan ,Y S Zhu ,S L Niu ,O Çakır ,H X Yang ,B L Wang ,X Lou ,M Y Dong ,J P Dai ,C J Tang ,G X Sun ,Q J Wang ,H J Lü ,H Y Chen ,G M Huang ,H L Dai ,Q L Xiu ,Jiawei Zhao ,Y J Mao ,C P Shen ,W X Gong ,Z H Wang ,Q M ,J W Zhang ,B C Ke ,Q A Malik ,J C Chen ,Y P Guo ,X H Mo ,K Y Liu ,Y B Zhao ,C D Fu ,Q J Xu ,S H Zhu ,M R Shepherd ,P X Shen ,T C Zhao ,Yudong Pu ,М Н Ачасов ,B J Liu ,Y J Sun ,X Y Niu ,A Kupść ,Y P Chu ,H M Hu ,L B Guo ,J Zhao ,S H Zhang ,J Y Liu ,M L Chen ,B X Zhang ,Lei Xu ,R A Briere ,K H Rashid ,L D Liu ,Y Z Sun ,L S Wang ,J F Chang ,C F Qiao ,J P Liu ,J J Zhang ,Y T Gu ,Z H Qin ,X J Zhang ,X S Kang ,S J Zhao ,K J Zhu ,Pengfei Duan ,Y Zhu ,K L He ,Y J Mo ,C L Luo ,Yang Gao ,R E Mitchell ,G S Huang ,B S Zou ,J F Sun ,J Z Bai ,X Q Li ,Z Y He ,X R Chen ,F H Liu ,Y H Zheng ,H W Yu ,L W Jiang ,Xin Fang ,Ning Qin ,S J Qian ,J B Jiao ,G F Xu ,J F Qiu ,D M Li ,X R Zhou ,J S Yu ,H Y Sheng ,D X Lin ,H Y Zhang ,J Fan ,S B Liu ,S L Olsen ,Y H Zhang ,D Ambrose ,Y L Han ,W B Yan ,C L Liu ,Z P Zhang ,J B Wei ,Z A Liu ,D H Zhang ,Z Y Wang ,C C Zhang ,J Q Zhang ,S X Du ,X L Li ,Hu Chen ,H L ,D Y Wang ,Y H Guan ,Zhao Liu ,J C Li ,C Z Yuan ,J G Messchendorp ,J P Zheng ,H S Chen ,X Y ,M H Ye ,J S Lange ,X N Li ,N Kalantar‐Nayestanaki ,X K Chu ,F F An ,Q Xu ,D W Bennett ,X F Wang ,Z J Sun ,P Patterí ,Yao Qin ,Y F Wang ,H H Liu ,X R Lyu ,Y H Yan ,L H Wu ,Y F Liang ,Y Xie ,J L Zhang ,B Y Zhang ,M G Zhao ,C F Redmer ,R G Ping ,G F Cao ,X Y Zhou ,Tingting Guo ,C X Liu ,Y K Heng ,H B Liu ,C Q Feng ,Z T Sun ,E H Thorndike ,H Peng ,X S Jiang ,S P Wen ,X L Kang ,J H Yin ,D P Jin ,G R Liao ,J H Zou

doi:10.1103/physrevlett.113.212002

Abstract

Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider at center-of-mass energies of sqrt[s]=4.23, 4.26, and 4.36 GeV, we observe e(+)e(-)→π(0)π(0)hc for the first time. The Born cross sections are measured and found to be about half of those of e(+)e(-)→π(+)π(-)hc within less than 2σ. In the π(0)hc mass spectrum, a structure at 4.02 GeV/c(2) is found. It is most likely to be the neutral isospin partner of the Zc(4020)(±) observed in the process of e(+)e(-)→π(+)π(-)hc being found. A fit to the π(0)hc invariant mass spectrum, with the width of the Zc(4020)(0) fixed to that of its charged isospin partner and possible interferences with non-Zc(4020)(0) amplitudes neglected, gives a mass of (4023.9±2.2±3.8) MeV/c(2) for the Zc(4020)(0), where the first error is statistical and the second systematic.

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