Observation of e+e−→γχc1 and search for e+e−→γχc0 , γχc2 , and γηc at s near 10.6 GeV at Belle

S Jia,T Kawasaki,P Krokovny,V Bansal,S Eidelman,T Kuhr,M Starič,E Waheed,R Van Tonder,G Karyan,P Chang,E Prencipe,N Gabyshev,K Senyo,Y Seino,S Ogawa,Z Doležal,R Kulasiri,M Merola,C Kiesling,E Solovieva,A Kuzmin,M Nakao,S Al Said,R Pestotnik,G Inguglia,J Macnaughton,S Cunliffe,M Nayak,T Sanuki,V Babu,O Schneider,S Pardi,T Aushev,R Itoh,K Tanida,W Ostrowicz,M Masuda,A Chen,A Rostomyan,L Li Gioi,A Ishikawa,T Bilka,S Sandilya,J Libby,P Goldenzweig,K Hayasaka,E Nakano,H Miyata,C Beleño,Y Iwasaki,D Liventsev,J Schueler,T Sumiyoshi,M Uchida,T Ferber,Y Yusa,J Haba,L Cao,A Frey,V Chekelian,S Uno,D Červenkov,P Križan,H Kichimi,A Garmash,M Bračko,T Matsuda,K Lalwani,D Cinabro,M Gelb,F Tenchini,Y Onuki,Y Usov,N Dash,V Vorobyev,D Epifanov,R Kroeger,Y Sakai,S Nishida,R Mizuk,V Savinov,H Hayashii,T Iijima,G Schnell,S Uehara,H Atmacan,C Schwanda,K Inami,Y Choi,B Bhuyan,R Mussa,M Iwasaki,W Sutcliffe,A Bobrov,D Kotchetkov,T Uglov,D Matvienko,D Joffe,G Pakhlova,M Lubej,I Adachi,S Korpar,R Ayad,S Di Carlo,K Chilikin,V Gaur,E Won,K Kinoshita,E Widmann,K Cho,B K Pal ,V Popov,Y B Li ,A B Kaliyar ,F Simon,A Bożek ,C H Li ,G Varner,J Kahn,J G Shiu ,S Paul,S Watanuki,Takashi Mori ,Y Tao,J H Yin ,P Kodyš,Z P Zhang ,H Ye,S B Yang ,G Russo,C.-L Hsu,J Y Lee ,T K Pedlar ,Z Liptak,J B Kim ,J E Fast ,B G Fulsom ,A Giri,S C Lee ,A Sokolov,Hiroyuki Ono ,M.-Z Wang,T A Shibata ,N K Nisar ,M Ritter,K J Nath ,Martin Berger ,P Wang,M Takizawa,K E Varvell ,Y J Kwon ,V Zhulanov,P.-C Lu,M Salehi,J S Lange ,S K Choi ,V Zhukova,C P Shen ,D Greenwald,B G Cheon ,D M Asner ,L E Piilonen ,J Strube ,H J Kim ,C H Wang ,H Yamamoto,T V Dong ,D Y Kim ,V Aulchenko,H Aihara,R Garg,Y Unno,L Šantelj ,V Zhilich,S L Olsen ,M E Sevior ,Z S Stottler ,W.-S Hou,Rajeev Kumar ,L K Li ,P Urquijo,X L Wang ,P K Behera ,I S Lee ,B Wang,W W Jacobs ,S Choudhury,Y Jin,Jyoti Prakash Biswal ,S H Kim ,C Z Yuan ,T E Browder

doi:10.1103/physrevd.98.092015

Abstract

Using data samples of 89.5 fb−1, 711.0 fb−1, and 121.4 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− collider at center-of-mass energies 10.52, 10.58, and 10.867 GeV, respectively, we study the exclusive reactions e+e−→γχcJ (J=0, 1, 2) and e+e−→γηc. A significant γχc1 signal is observed for the first time at s=10.58 GeV with a significance of 5.1σ including systematic uncertainties. No significant excesses for γχc0, γχc2, and γηc final states are found, and we set 90% credibility level upper limits on the Born cross sections (σB) at 10.52 GeV, 10.58 GeV, and 10.867 GeV. Together with cross sections measured by BESIII at lower center-of-mass energies, the energy dependency of σB(e+e−→γχc1) is obtained.Received 24 October 2018DOI:https://doi.org/10.1103/PhysRevD.98.092015Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNonrelativistic QCDPerturbative QCDQuantum chromodynamicsParticles & Fields

Highlights

Using data samples of 89.5 fb−1, 711.0 fb−1, and 121.4 fb−1 collected with the Belle detector at the KEKB asymmetric-energy eþe− collider at center-of-mass energies 10.52, 10.58, and 10.867 GeV, respectively, we study the exclusive reactions epþeffiffi− → γχcJ (J 1⁄4 0, 1, 2) and eþe− → γηc
A significant γχc1 signal is observed for the first time at s 1⁄4 10.58 GeV with a significance of 5.1σ including systematic uncertainties
Together with cross sections measured by BESIII at lower center-of-mass energies, the energy dependency of σBðeþe− → γχc1Þ is obtained

Summary

Published by the American Physical Society

We report cross-section measurements for the exclusivpe ffiffireactions eþe− → γχcJ and γηc with data recorded at s ∼ 10.6 GeV by the Belle experiment at the KEKB asymmetric-energy eþe− collider [17,18]. If there are more than two photons, to suppress the background from the ISR process eþe− → γISRψð2SÞ → γISRγχcJ, an extra photon (γext) besides γh and γl is selected, and Mðγextγlμþμ−Þ < 3.60 GeV=c2 or Mðγextγlμþμ−Þ > 3.78 GeV=c2 is required.

Kinematic fits with χ

There are several sources of systematic uncertainty in the

Comparison of

Sum in quadrature

Findings

Methods