Observation of ϒ(2S)→γη_{b}(1S) Decay

B G Fulsom; T K Pedlar; I Adachi; H Aihara; S Al Said; D M Asner; H Atmacan; V Aulchenko; T Aushev; R Ayad; V Babu; I Badhrees; A M Bakich; V Bansal; P Behera; C Beleño; M Berger; V Bhardwaj; B Bhuyan; T Bilka; J Biswal; A Bondar; G Bonvicini; A Bozek; M Bračko; T E Browder; L Cao; D Červenkov; V Chekelian; A Chen; B G Cheon; K Chilikin; K Cho; S-K Choi; Y Choi; S Choudhury; D Cinabro; S Cunliffe; N Dash; S Di Carlo; J Dingfelder; Z Doležal; T V Dong; Z Drásal; S Eidelman; D Epifanov; J E Fast; T Ferber; R Garg; V Gaur; N Gabyshev; A Garmash; M Gelb; A Giri; P Goldenzweig; E Guido; J Haba; K Hayasaka; H Hayashii; S Hirose; W-S Hou; T Iijima; K Inami; G Inguglia; A Ishikawa; R Itoh; M Iwasaki; Y Iwasaki; W W Jacobs; H B Jeon; S Jia; Y Jin; D Joffe; K K Joo; T Julius; T Kawasaki; H Kichimi; C Kiesling; D Y Kim; H J Kim; J B Kim; K T Kim; S H Kim; K Kinoshita; P Kodyš; S Korpar; D Kotchetkov; P Križan; R Kroeger; P Krokovny; T Kuhr; R Kulasiri; A Kuzmin; Y-J Kwon; J S Lange; I S Lee; S C Lee; L K Li; Y B Li; L Li Gioi; J Libby; D Liventsev; M Lubej; T Luo; M Masuda; T Matsuda; D Matvienko; M Merola; K Miyabayashi; H Miyata; R Mizuk; G B Mohanty; H K Moon; T Mori; R Mussa; M Nakao; T Nanut; K J Nath; Z Natkaniec; M Nayak; M Niiyama; N K Nisar; S Nishida; S Ogawa; S Okuno; H Ono; P Pakhlov; G Pakhlova; B Pal; S Pardi; H Park; S Paul; R Pestotnik; L E Piilonen; V Popov; E Prencipe; A Rabusov; M Ritter; A Rostomyan; G Russo; Y Sakai; M Salehi; S Sandilya; L Santelj; T Sanuki; V Savinov; O Schneider; G Schnell; C Schwanda; Y Seino; K Senyo; M E Sevior; V Shebalin; C P Shen; T-A Shibata; J-G Shiu; B Shwartz; F Simon; J B Singh; A Sokolov; E Solovieva; M Starič; J F Strube; M Sumihama; K Sumisawa; T Sumiyoshi; W Sutcliffe; M Takizawa; U Tamponi; K Tanida; F Tenchini; M Uchida; T Uglov; Y Unno; S Uno; P Urquijo; S E Vahsen; C Van Hulse; R Van Tonder; G Varner; A Vinokurova; V Vorobyev; A Vossen; B Wang; C H Wang; P Wang; X L Wang; M Watanabe; S Watanuki; E Widmann; E Won; H Ye; J H Yin; C Z Yuan; Z P Zhang; V Zhilich; V Zhukova; V Zhulanov; A Zupanc; Belle Collaboration

doi:10.1103/PhysRevLett.121.232001

Observation of ϒ(2S)→γη_{b}(1S) Decay

Phys Rev Lett. 2018 Dec 7;121(23):232001. doi: 10.1103/PhysRevLett.121.232001.

Authors

B G Fulsom¹, T K Pedlar², I Adachi^{3

4}, H Aihara⁵, S Al Said^{6

7}, D M Asner⁸, H Atmacan⁹, V Aulchenko^{10

11}, T Aushev¹², R Ayad⁷, V Babu¹³, I Badhrees^{14

7}, A M Bakich¹⁵, V Bansal¹, P Behera¹⁶, C Beleño¹⁷, M Berger¹⁸, V Bhardwaj¹⁹, B Bhuyan²⁰, T Bilka²¹, J Biswal²², A Bondar^{10

11}, G Bonvicini²³, A Bozek²⁴, M Bračko^{22

25}, T E Browder²⁶, L Cao²⁷, D Červenkov²¹, V Chekelian²⁸, A Chen²⁹, B G Cheon³⁰, K Chilikin³¹, K Cho³², S-K Choi³³, Y Choi³⁴, S Choudhury³⁵, D Cinabro²³, S Cunliffe³⁶, N Dash³⁷, S Di Carlo³⁸, J Dingfelder³⁹, Z Doležal²¹, T V Dong^{3

4}, Z Drásal²¹, S Eidelman^{10

31

11}, D Epifanov^{10

11}, J E Fast¹, T Ferber³⁶, R Garg⁴⁰, V Gaur⁴¹, N Gabyshev^{10

11}, A Garmash^{10

11}, M Gelb²⁷, A Giri³⁵, P Goldenzweig²⁷, E Guido⁴², J Haba^{3

4}, K Hayasaka⁴³, H Hayashii⁴⁴, S Hirose⁴⁵, W-S Hou⁴⁶, T Iijima^{45

47}, K Inami⁴⁵, G Inguglia³⁶, A Ishikawa⁴⁸, R Itoh^{3

4}, M Iwasaki⁴⁹, Y Iwasaki⁴, W W Jacobs⁵⁰, H B Jeon⁵¹, S Jia⁵², Y Jin⁵, D Joffe⁵³, K K Joo⁵⁴, T Julius⁵⁵, T Kawasaki⁴³, H Kichimi⁴, C Kiesling²⁸, D Y Kim⁵⁶, H J Kim⁵¹, J B Kim⁵⁷, K T Kim⁵⁷, S H Kim³⁰, K Kinoshita⁵⁸, P Kodyš²¹, S Korpar^{22

25}, D Kotchetkov²⁶, P Križan^{22

59}, R Kroeger⁶⁰, P Krokovny^{10

11}, T Kuhr⁶¹, R Kulasiri⁵³, A Kuzmin^{10

11}, Y-J Kwon⁶², J S Lange⁶³, I S Lee³⁰, S C Lee⁵¹, L K Li⁶⁴, Y B Li⁶⁵, L Li Gioi²⁸, J Libby¹⁶, D Liventsev^{4

41}, M Lubej²², T Luo⁶⁶, M Masuda⁶⁷, T Matsuda⁶⁸, D Matvienko^{10

31

11}, M Merola^{69

70}, K Miyabayashi⁴⁴, H Miyata⁴³, R Mizuk^{31

71

12}, G B Mohanty¹³, H K Moon⁵⁷, T Mori⁴⁵, R Mussa⁴², M Nakao^{3

4}, T Nanut²², K J Nath²⁰, Z Natkaniec²⁴, M Nayak^{4

23}, M Niiyama⁷², N K Nisar⁷³, S Nishida^{3

4}, S Ogawa⁷⁴, S Okuno⁷⁵, H Ono^{76

43}, P Pakhlov^{31

71}, G Pakhlova^{31

12}, B Pal⁸, S Pardi⁶⁹, H Park⁵¹, S Paul⁷⁷, R Pestotnik²², L E Piilonen⁴¹, V Popov^{31

12}, E Prencipe⁷⁸, A Rabusov⁷⁷, M Ritter⁶¹, A Rostomyan³⁶, G Russo⁶⁹, Y Sakai^{3

4}, M Salehi^{61

79}, S Sandilya⁵⁸, L Santelj⁴, T Sanuki⁴⁸, V Savinov⁷³, O Schneider⁸⁰, G Schnell^{81

82}, C Schwanda⁸³, Y Seino⁴³, K Senyo⁸⁴, M E Sevior⁵⁵, V Shebalin^{10

11}, C P Shen⁵², T-A Shibata⁸⁵, J-G Shiu⁴⁶, B Shwartz^{10

11}, F Simon^{28

86}, J B Singh⁴⁰, A Sokolov⁸⁷, E Solovieva^{31

12}, M Starič²², J F Strube¹, M Sumihama⁸⁸, K Sumisawa^{3

4}, T Sumiyoshi⁸⁹, W Sutcliffe²⁷, M Takizawa^{90

91

92}, U Tamponi⁴², K Tanida⁹³, F Tenchini⁵⁵, M Uchida⁸⁵, T Uglov^{31

12}, Y Unno³⁰, S Uno^{3

4}, P Urquijo⁵⁵, S E Vahsen²⁶, C Van Hulse⁸¹, R Van Tonder²⁷, G Varner²⁶, A Vinokurova^{10

11}, V Vorobyev^{10

31

11}, A Vossen⁹⁴, B Wang⁵⁸, C H Wang⁹⁵, P Wang⁶⁴, X L Wang⁶⁶, M Watanabe⁴³, S Watanuki⁴⁸, E Widmann¹⁸, E Won⁵⁷, H Ye³⁶, J H Yin⁶⁴, C Z Yuan⁶⁴, Z P Zhang⁹⁶, V Zhilich^{10

11}, V Zhukova^{31

71}, V Zhulanov^{10

11}, A Zupanc^{22

59}; Belle Collaboration

Affiliations

¹ Pacific Northwest National Laboratory, Richland, Washington 99352.
² Luther College, Decorah, Iowa 52101.
³ SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193.
⁴ High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801.
⁵ Department of Physics, University of Tokyo, Tokyo 113-0033.
⁶ Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589.
⁷ Department of Physics, Faculty of Science, University of Tabuk, Tabuk 71451.
⁸ Brookhaven National Laboratory, Upton, New York 11973.
⁹ University of South Carolina, Columbia, South Carolina 29208.
¹⁰ Budker Institute of Nuclear Physics SB RAS, Novosibirsk 630090.
¹¹ Novosibirsk State University, Novosibirsk 630090.
¹² Moscow Institute of Physics and Technology, Moscow Region 141700.
¹³ Tata Institute of Fundamental Research, Mumbai 400005.
¹⁴ King Abdulaziz City for Science and Technology, Riyadh 11442.
¹⁵ School of Physics, University of Sydney, New South Wales 2006.
¹⁶ Indian Institute of Technology Madras, Chennai 600036.
¹⁷ II. Physikalisches Institut, Georg-August-Universität Göttingen, 37073 Göttingen.
¹⁸ Stefan Meyer Institute for Subatomic Physics, Vienna 1090.
¹⁹ Indian Institute of Science Education and Research Mohali, SAS Nagar, 140306.
²⁰ Indian Institute of Technology Guwahati, Assam 781039.
²¹ Faculty of Mathematics and Physics, Charles University, 121 16 Prague.
²² J. Stefan Institute, 1000 Ljubljana.
²³ Wayne State University, Detroit, Michigan 48202.
²⁴ H. Niewodniczanski Institute of Nuclear Physics, Krakow 31-342.
²⁵ University of Maribor, 2000 Maribor.
²⁶ University of Hawaii, Honolulu, Hawaii 96822.
²⁷ Institut für Experimentelle Teilchenphysik, Karlsruher Institut für Technologie, 76131 Karlsruhe.
²⁸ Max-Planck-Institut für Physik, 80805 München.
²⁹ National Central University, Chung-li 32054.
³⁰ Hanyang University, Seoul 133-791.
³¹ P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991.
³² Korea Institute of Science and Technology Information, Daejeon 305-806.
³³ Gyeongsang National University, Chinju 660-701.
³⁴ Sungkyunkwan University, Suwon 440-746.
³⁵ Indian Institute of Technology Hyderabad, Telangana 502285.
³⁶ Deutsches Elektronen-Synchrotron, 22607 Hamburg.
³⁷ Indian Institute of Technology Bhubaneswar, Satya Nagar 751007.
³⁸ LAL, Université Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, Orsay F-91898.
³⁹ University of Bonn, 53115 Bonn.
⁴⁰ Panjab University, Chandigarh 160014.
⁴¹ Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061.
⁴² INFN-Sezione di Torino, 10125 Torino.
⁴³ Niigata University, Niigata 950-2181.
⁴⁴ Nara Women's University, Nara 630-8506.
⁴⁵ Graduate School of Science, Nagoya University, Nagoya 464-8602.
⁴⁶ Department of Physics, National Taiwan University, Taipei 10617.
⁴⁷ Kobayashi-Maskawa Institute, Nagoya University, Nagoya 464-8602.
⁴⁸ Department of Physics, Tohoku University, Sendai 980-8578.
⁴⁹ Osaka City University, Osaka 558-8585.
⁵⁰ Indiana University, Bloomington, Indiana 47408.
⁵¹ Kyungpook National University, Daegu 702-701.
⁵² Beihang University, Beijing 100191.
⁵³ Kennesaw State University, Kennesaw, Georgia 30144.
⁵⁴ Chonnam National University, Kwangju 660-701.
⁵⁵ School of Physics, University of Melbourne, Victoria 3010.
⁵⁶ Soongsil University, Seoul 156-743.
⁵⁷ Korea University, Seoul 136-713.
⁵⁸ University of Cincinnati, Cincinnati, Ohio 45221.
⁵⁹ Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana.
⁶⁰ University of Mississippi, University, Mississippi 38677.
⁶¹ Ludwig Maximilians University, 80539 Munich.
⁶² Yonsei University, Seoul 120-749.
⁶³ Justus-Liebig-Universität Gießen, 35392 Gießen.
⁶⁴ Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049.
⁶⁵ Peking University, Beijing 100871.
⁶⁶ Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) and Institute of Modern Physics, Fudan University, Shanghai 200443.
⁶⁷ Earthquake Research Institute, University of Tokyo, Tokyo 113-0032.
⁶⁸ University of Miyazaki, Miyazaki 889-2192.
⁶⁹ INFN-Sezione di Napoli, 80126 Napoli.
⁷⁰ Università di Napoli Federico II, 80055 Napoli.
⁷¹ Moscow Physical Engineering Institute, Moscow 115409.
⁷² Kyoto University, Kyoto 606-8502.
⁷³ University of Pittsburgh, Pittsburgh, Pennsylvania 15260.
⁷⁴ Toho University, Funabashi 274-8510.
⁷⁵ Kanagawa University, Yokohama 221-8686.
⁷⁶ Nippon Dental University, Niigata 951-8580.
⁷⁷ Department of Physics, Technische Universität München, 85748 Garching.
⁷⁸ Forschungszentrum Jülich, 52425 Jülich.
⁷⁹ University of Malaya, 50603 Kuala Lumpur.
⁸⁰ École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015.
⁸¹ University of the Basque Country UPV/EHU, 48080 Bilbao.
⁸² IKERBASQUE, Basque Foundation for Science, 48013 Bilbao.
⁸³ Institute of High Energy Physics, Vienna 1050.
⁸⁴ Yamagata University, Yamagata 990-8560.
⁸⁵ Tokyo Institute of Technology, Tokyo 152-8550.
⁸⁶ Excellence Cluster Universe, Technische Universität München, 85748 Garching.
⁸⁷ Institute for High Energy Physics, Protvino 142281.
⁸⁸ Gifu University, Gifu 501-1193.
⁸⁹ Tokyo Metropolitan University, Tokyo 192-0397.
⁹⁰ J-PARC Branch, KEK Theory Center, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801.
⁹¹ Theoretical Research Division, Nishina Center, RIKEN, Saitama 351-0198.
⁹² Showa Pharmaceutical University, Tokyo 194-8543.
⁹³ Advanced Science Research Center, Japan Atomic Energy Agency, Naka 319-1195.
⁹⁴ Duke University, Durham, North Carolina 27708.
⁹⁵ National United University, Miao Li 36003.
⁹⁶ University of Science and Technology of China, Hefei 230026.

PMID: 30576207
DOI: 10.1103/PhysRevLett.121.232001

Abstract

We report the observation of ϒ(2S)→γη_{b}(1S) decay based on an analysis of the inclusive photon spectrum of 24.7 fb^{-1} of e^{+}e^{-} collisions at the ϒ(2S) center-of-mass energy collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We measure a branching fraction of B[ϒ(2S)→γη_{b}(1S)]=(6.1_{-0.7-0.6}^{+0.6+0.9})×10^{-4} and derive an η_{b}(1S) mass of 9394.8_{-3.1-2.7}^{+2.7+4.5} MeV/c^{2}, where the uncertainties are statistical and systematic, respectively. The significance of our measurement is greater than 7 standard deviations, constituting the first observation of this decay mode.