Phys. Rev. Lett.
93,
021601
(2004)
[5 pages]
Observation of Large CP Violation and Evidence for Direct CP Violation in B0→π+π- Decays
K. Abe et al. Belle Collaboration
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K. Abe5, K. Abe38, N. Abe41, T. Abe5, I. Adachi5, H. Aihara40, K. Akai5, M. Akatsu18, M. Akemoto5, Y. Asano45, T. Aso44, V. Aulchenko1, T. Aushev9, A. M. Bakich35, Y. Ban28, S. Banerjee36, A. Bay14, I. Bedny1, I. Bizjak10, A. Bondar1, A. Bozek22, M. Bračko16,10, T. E. Browder4, Y. Chao21, K.-F. Chen21, B. G. Cheon34, R. Chistov9, S.-K. Choi49, Y. Choi34, A. Chuvikov29, S. Cole35, M. Danilov9, J. Dragic17, A. Drutskoy9, S. Eidelman1, V. Eiges9, Y. Enari18, D. Epifanov1, J. Flanagan5, K. Furukawa5, N. Gabyshev5, A. Garmash29, T. Gershon5, B. Golob15,10, J. Haba5, K. Hara26, N. C. Hastings5, H. Hayashii19, M. Hazumi5, L. Hinz14, T. Hokuue18, Y. Hoshi38, W.-S. Hou21, Y. B. Hsiung21,*, H.-C. Huang21, T. Iijima18, H. Ikeda5, K. Inami18, A. Ishikawa5, H. Ishino41, R. Itoh5, H. Iwasaki5, M. Iwasaki40, Y. Iwasaki5, H. Kakuno41, T. Kamitani5, J. H. Kang48, J. S. Kang12, P. Kapusta22, S. U. Kataoka19, N. Katayama5, H. Kawai2, T. Kawasaki24, A. Kibayashi41, H. Kichimi5, E. Kikutani5, H. J. Kim48, J. H. Kim34, S. K. Kim33, K. Kinoshita50, P. Koppenburg5, S. Korpar16,10, P. Križan15,10, P. Krokovny1, S. Kumar27, A. Kuzmin1, Y.-J. Kwon48, J. S. Lange3,30, G. Leder8, S. H. Lee33, Y.-J. Lee21, T. Lesiak22, J. Li32, A. Limosani17, S.-W. Lin21, D. Liventsev9, J. MacNaughton8, F. Mandl8, D. Marlow29, H. Matsumoto24, T. Matsumoto42, A. Matyja22, S. Michizono5, T. Mimashi5, W. Mitaroff8, K. Miyabayashi19, H. Miyake26, H. Miyata24, D. Mohapatra46, G. R. Moloney17, A. Murakami31, T. Nagamine39, Y. Nagasaka6, T. Nakadaira40, T. T. Nakamura5, E. Nakano25, M. Nakao5, H. Nakazawa5, Z. Natkaniec22, K. Neichi38, S. Nishida5, O. Nitoh43, S. Noguchi19, T. Nozaki5, S. Ogawa37, Y. Ogawa5, K. Ohmi5, T. Ohshima18, N. Ohuchi5, K. Oide5, T. Okabe18, S. Okuno11, S. L. Olsen4, W. Ostrowicz22, H. Ozaki5, P. Pakhlov9, H. Palka22, C. W. Park12, H. Park13, N. Parslow35, L. E. Piilonen46, N. Root1, M. Rozanska22, H. Sagawa5, Y. Sakai5, O. Schneider14, J. Schümann21, C. Schwanda8, A. J. Schwartz50, S. Semenov9, K. Senyo18, H. Shibuya37, T. Shidara5, B. Shwartz1, V. Sidorov1, J. B. Singh27, N. Soni27, R. Stamen5, S. Stanič45,†, M. Starič10, R. Sugahara5, K. Sumisawa26, T. Sumiyoshi42, K. Suzuki5, S. Suzuki47, O. Tajima39, F. Takasaki5, K. Tamai5, N. Tamura24, M. Tanaka5, M. Tawada5, Y. Teramoto25, T. Tomura40, T. Tsuboyama5, T. Tsukamoto5, S. Uehara5, T. Uglov9, K. Ueno21, Y. Unno2, S. Uno5, G. Varner4, K. E. Varvell35, C. C. Wang21, C. H. Wang20, M.-Z. Wang21, Y. Watanabe41, B. D. Yabsley46, Y. Yamada5, A. Yamaguchi39, Y. Yamashita23, M. Yamauchi5, H. Yanai24, Heyoung Yang33, J. Ying28, M. Yokoyama40, M. Yoshida5, Y. Yusa39, C. C. Zhang7, Z. P. Zhang32, T. Ziegler29, D. Žontar15,10, and D. Zürcher14 (Belle Collaboration)
1Budker Institute of Nuclear Physics, Novosibirsk
2Chiba University, Chiba
3University of Frankfurt, Frankfurt
4University of Hawaii, Honolulu, Hawaii 96822
5High Energy Accelerator Research Organization (KEK), Tsukuba
6Hiroshima Institute of Technology, Hiroshima
7Institute of High Energy Physics, Chinese Academy of Sciences, Beijing
8Institute of High Energy Physics, Vienna
9Institute for Theoretical and Experimental Physics, Moscow
10J. Stefan Institute, Ljubljana
11Kanagawa University, Yokohama
12Korea University, Seoul
13Kyungpook National University, Taegu
14Swiss Federal Institute of Technology of Lausanne, EPFL, Lausanne
15University of Ljubljana, Ljubljana
16University of Maribor, Maribor
17University of Melbourne, Victoria
18Nagoya University, Nagoya
19Nara Women’s University, Nara
20National United University, Miao Li
21Department of Physics, National Taiwan University, Taipei
22H. Niewodniczanski Institute of Nuclear Physics, Krakow
23Nihon Dental College, Niigata
24Niigata University, Niigata
25Osaka City University, Osaka
26Osaka University, Osaka
27Panjab University, Chandigarh
28Peking University, Beijing
29Princeton University, Princeton, New Jersey 08545
30RIKEN BNL Research Center, Upton, New York 11973
31Saga University, Saga
32University of Science and Technology of China, Hefei
33Seoul National University, Seoul
34Sungkyunkwan University, Suwon
35University of Sydney, Sydney, New South Wales
36Tata Institute of Fundamental Research, Bombay
37Toho University, Funabashi
38Tohoku Gakuin University, Tagajo
39Tohoku University, Sendai
40Department of Physics, University of Tokyo, Tokyo
41Tokyo Institute of Technology, Tokyo
42Tokyo Metropolitan University, Tokyo
43Tokyo University of Agriculture and Technology, Tokyo
44Toyama National College of Maritime Technology, Toyama
45University of Tsukuba, Tsukuba
46Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
47Yokkaichi University, Yokkaichi
48Yonsei University, Seoul
49Gyeongsang National University, Chinju
50University of Cincinnati, Cincinnati, Ohio
Received 18 January 2004; published 6 July 2004
We report the first observation of CP violation in B0→π+π- decays based on 152×106 ϒ(4S)→BB̅ decays collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct a B0→π+π- CP eigenstate and identify the flavor of the accompanying B meson from its decay products. From the distribution of the time intervals between the two B meson decay points, we obtain Aππ=+0.58±0.15(stat)±0.07(syst) and Sππ=-1.00±0.21(stat)±0.07(syst). We rule out the CP-conserving case, Aππ=Sππ=0, at a level of 5.2 standard deviations. We also find evidence for direct CP violation with a significance at or greater than 3.2 standard deviations for any Sππ value.
© 2004 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.93.021601
DOI:
10.1103/PhysRevLett.93.021601
PACS:
13.25.Hw, 11.30.Er, 12.15.Hh
*On leave from Fermi National Accelerator Laboratory, Batavia, IL 60510, USA. †On leave from Nova Gorica Polytechnic, Nova Gorica.
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