Two-photon widths of theχc0,2states and helicity analysis forχc2→γγ

M Ablikim,Y S Zhu,Q Ouyang,M X Luo,T Hu,F Feldbauer,H M Hu,L Fava,R A Briere,J S Lange,B Zhong,X S Qin,X P Xu,Y Ban,A Zallo,S P Wen,Lei Li,J F Hu,A Calcaterra,X Y Shen,G R Liao,H Loehner,S X Du,X B Ji,Feng Liu,O Bondarenko,M Pelizaeus,Y T Gu,Y Zhang,D H Wei,Y Yuan,C X Yu,Z L Hou,P Weidenkaff,Y J Mao,Z P Zheng,A Sarantsev,R G Ping,Z J Xiao,Y Nefedov,C J Tang,L L Jiang,Q J Li,J Min,D P Jin,S Spataro,C Morales Morales,G F Xu,Y Zeng,X T Huang,I B Nikolaev,X Y Zhang,M Lv,M Ullrich,Z P Zhang,X K Zhou,S Jin,Fang Liu,J B Jiao,Z Jiao,J C Li,M H Ye,Z Ning,R Poling,G X Sun,B Spruck,C S Ji,C D Fu,W Gradl,W Kuehn,C Motzko,R E Mitchell,C Z Yuan,K H Rashid,Y K Heng,M Shao,K Goetzen,M Bertani,M Destefanis,J Fang,X Y Song,C Nicholson,T Hussain,Q Zhao,J H Zou,E Boger,G F Cao,Z B Li,Z H Qin,E H Thorndike,M Y Dong,X S Jiang,A Q Guo,Cui Li,Z Y He,J P Dai,H Y Sheng,J Zhong,J G Messchendorp,J K C Leung,A A Zafar,Q L Xiu,J Z Bai,Y B Zhao,J G Lu,H S Chen,H L Dai,Q An,D Cronin-Hennessy,Y F Liang,D Toth,X H Mo,Y P Chu,Y Ding,S S Fang,X Q Hao,Z A Liu,F A Harris,X Tang,Y L Han,X Cai,Z Y Deng,J C Chen,X F Wang,S L Olsen,M Maggiora,Q A Malik,B S Zou,I Denysenko,S S Sun,Cheng Li,H Y Zhang,B X Yu,K X Zhao,Kun Liu,J Zhuang,S Pacetti,W B Yan,L Y Dong,C L Luo,M G Zhao,T Held,Ling Zhao,M R Shepherd,E Prencipe,M Qi,C P Shen,F Li,K L He,M H Gu,K J Zhu,J F Qiu,M Greco,D M Li,C C Zhang,T J Min,S J Zhao,W X Gong,Y H Yan,N Yu Muchnoi,G Li,Y H Guan,W L Yuan,M Kavatsyuk,L H Wu,Zhiqing Liu,M He,S Ma,F E Maas,X L Luo,G Rong,Z P Mao,L B Guo,B J Liu,C Zhu,D Ambrose ,S Qian,Y Xie ,W Lai,P L Liu,Y T Liang,W M Ding,Y Z Sun,H L ,Z Y Zhang,J Schulze,W G Li,H P Cheng,X Q Li,M Ye,K Peters,K Wang,L Xia ,Y Q Wang,T C Zhao,Lu Jia ,Y Yang,Han Liu ,Y Gao,H J Lü ,H W Liu,J P Zheng,P L Wang,G R Lu,Zhao Liu ,Z Wang,Jin Chang ,Y C Xu ,B Wang,W Wu,Z T Sun,Heng Xu ,X J Zhang,J W Zhang,J Q Zhang,L L Wang,V Bytev,М Н Ачасов ,Z Xu ,Y F Wang,Y H Zhang,K Y Liu,B Q Wang,A Denig,G Chen,F H Liu,X R Zhou,A Zhemchugov,X Zhao ,Tao Yang ,B Zheng,J M Bian,G Chelkov,X R Lü ,L Yan,Fei Xue ,C Q Feng,Y B Chen,Zhiqiang Liu,J Becker,F F An,X R Li,Bin Huang ,C S J Pun,J F Sun,Q G Wen,J P Liu,Zhi‐Wei Sun ,J S Yu,Yao Qin ,H S Zhao,H B Liu,S B Liu,J L Ping,M Wang,I R Boyko ,K Li,Q J Wang,J W Park,Q Wang,X N Li,H X Yang,Zhi Wang ,L S Wang,W D Li,Z G Wang,J Z Zhang,Y Ma,H B Li,Y B Liu,X T Liao,B Y Zhang,Nengyou Wu ,Zhen Xue ,H L Tian,C F Qiao,T R Zhang,G M Huang,Niuqi Li ,Q Ji,L Zhang,S X Wu,Y Zheng ,X H Liu,Z H An,Q M ,S G Wang,Y Liu,X L Wang,F Jing ,P Wang,G Xu ,C X Liu,J Fu ,X Sun ,B X Zhang,T Luo,X D Ruan,J S Huang,G Zhao,N Berger,Shushan Chen ,X Zhu ,Kai Li ,M L Chen,D Dedovich,D H Sun,H M Liu,Z A Zhu,C Y Liu,C L Liu,J G Zhang,R Baldini Ferroli ,H H Zhang,Y Chen,Z Zhao ,Chao–Qiang Geng ,S H Zhu,X Y ,C L ,M Werner,S L Li,Zhou Li ,H Ye,Q J Xu,Y J Sun,Shiqi Yu ,J Y Zhang,Y P Guo,J W Zhao,Z Y Wang,J X Zuo,Yifan Yang ,Y S Zhang,Tian Ma ,S H Zhang,Y D Wang,Y Huang ,F C ,H H Liu,N Kalantar‐Nayestanaki ,J Zhang,Y P Lu,U Wiedner,G Varner ,H S Mao ,C H Li,D H Zhang,X L Li,Q W Lü ,Y M Zhu,H Liu,X L Ji,X Liu

doi:10.1103/physrevd.85.112008

Abstract

Based on a data sample of 106×106 ψ′ events collected with the BESIII detector, the decays ψ′→γχc0,2, χc0,2→γγ are studied to determine the two-photon widths of the χc0,2 states. The two-photon decay branching fractions are determined to be B(χc0→γγ)=(2.24±0.19±0.12±0.08)×10−4 and B(χc2→γγ)=(3.21±0.18±0.17±0.13)×10−4. From these, the two-photon widths are determined to be Γγγ(χc0)=(2.33±0.20±0.13±0.17) keV, Γγγ(χc2)=(0.63±0.04±0.04±0.04) keV, and R=Γγγ(χc2)/Γγγ(χc0)=0.271±0.029±0.013±0.027, where the uncertainties are statistical, systematic, and those from the PDG B(ψ′→γχc0,2) and Γ(χc0,2) errors, respectively. The ratio of the two-photon widths for helicity λ=0 and helicity λ=2 components in the decay χc2→γγ is measured for the first time to be f0/2=Γγγλ=0(χc2)/Γγγλ=2(χc2)=0.00±0.02±0.02.Received 18 May 2012DOI:https://doi.org/10.1103/PhysRevD.85.112008© 2012 American Physical Society

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