Phys. Rev. D
68,
012001
(2003)
[15 pages]
Evidence for CP-violating asymmetries in B0→π+π- decays and constraints on the CKM angle φ2
K. Abe et al. (Belle Collaboration)
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K. Abe7, K. Abe41, N. Abe44, T. Abe42, I. Adachi7, H. Aihara43, K. Akai7, M. Akatsu21, M. Akemoto7, Y. Asano47, T. Aushev11, A. M. Bakich39, Y. Ban32, E. Banas26, A. Bay17, I. Bedny2, P. K. Behera48, I. Bizjak12, A. Bondar2, A. Bozek26, M. Bračko19,12, J. Brodzicka26, T. E. Browder6, B. C. K. Casey6, P. Chang25, K.-F. Chen25, B. G. Cheon38, R. Chistov11, S.-K. Choi52, Y. Choi38, Y. K. Choi38, M. Danilov11, J. Dragic20, A. Drutskoy11, S. Eidelman2, V. Eiges11, C. W. Everton20, J. Flanagan7, C. Fukunaga45, K. Furukawa7, N. Gabyshev7, A. Garmash2,7, T. Gershon7, B. Golob18,12, R. Guo23, C. Hagner49, K. Hara30, N. C. Hastings7, K. Hasuko34, H. Hayashii22, M. Hazumi7, T. Higuchi7, L. Hinz17, T. Hojo30, T. Hokuue21, Y. Hoshi41, W.-S. Hou25, Y. B. Hsiung25, H.-C. Huang25, T. Igaki21, Y. Igarashi7, T. Iijima21, H. Ikeda7, K. Inami21, A. Ishikawa21, H. Ishino44, R. Itoh7, H. Iwasaki7, Y. Iwasaki7, H. K. Jang37, J. S. Kang14, P. Kapusta26, S. U. Kataoka22, N. Katayama7, G. Katano7, H. Kawai43, N. Kawamura1, T. Kawasaki28, H. Kichimi7, M. Kikuchi7, E. Kikutani7, D. W. Kim38, H. J. Kim51, H. O. Kim38, Hyunwoo Kim14, J. H. Kim38, S. K. Kim37, S. Kobayashi35, S. Korpar19,12, P. Križan18,12, P. Krokovny2, T. Kubo7, R. Kulasiri4, S. Kumar31, A. Kuzmin2, Y.-J. Kwon51, J. S. Lange5,34, G. Leder10, S. H. Lee37, J. Li36, S.-W. Lin25, J. MacNaughton10, F. Mandl10, D. Marlow33, S. Matsumoto3, T. Matsumoto45, S. Michizono7, T. Mimashi7, W. Mitaroff10, K. Miyabayashi22, H. Miyake30, H. Miyata28, G. R. Moloney20, T. Mori3, A. Murakami35, Y. Nagasaka8, T. Nakadaira43, T. T. Nakamura7, E. Nakano29, M. Nakao7, H. Nakayama7, J. W. Nam38, K. Neichi41, S. Nishida15, O. Nitoh46, S. Noguchi22, T. Nozaki7, S. Ogawa40, Y. Ogawa7, K. Ohmi7, Y. Ohnishi7, T. Ohshima21, N. Ohuchi7, T. Okabe21, S. Okuno13, S. L. Olsen6, Y. Onuki28, W. Ostrowicz26, H. Ozaki7, H. Palka26, C. W. Park14, H. Park16, K. S. Park38, L. S. Peak39, J.-P. Perroud17, M. Peters6, L. E. Piilonen49, M. Rozanska26, K. Rybicki26, H. Sagawa7, S. Saitoh7, Y. Sakai7, T. R. Sarangi48, M. Satapathy48, A. Satpathy7,4, O. Schneider17, S. Schrenk4, J. Schümann25, C. Schwanda7,10, S. Semenov11, K. Senyo21, M. E. Sevior20, H. Shibuya40, T. Shidara7, B. Shwartz2, V. Sidorov2, J. B. Singh31, S. Stanič7,*, M. Starič12, R. Sugahara7, A. Sugiyama21, K. Sumisawa7, T. Sumiyoshi45, K. Suzuki7, S. Suzuki50, T. Takahashi29, F. Takasaki7, K. Tamai7, N. Tamura28, J. Tanaka43, M. Tanaka7, M. Tawada7, G. N. Taylor20, Y. Teramoto29, S. Tokuda21, T. Tomura43, K. Trabelsi6, T. Tsuboyama7, T. Tsukamoto7, S. Uehara7, Y. Unno53, S. Uno7, N. Uozaki43, S. E. Vahsen33, G. Varner6, K. E. Varvell39, C. C. Wang25, C. H. Wang24, J. G. Wang49, M.-Z. Wang25, Y. Watanabe44, E. Won14, B. D. Yabsley49, Y. Yamada7, A. Yamaguchi42, H. Yamamoto42, Y. Yamashita27, Y. Yamashita43, M. Yamauchi7, M. Yokoyama43, M. Yoshida7, C. C. Zhang9, Z. P. Zhang36, V. Zhilich2, and D. Žontar18,12 (Belle Collaboration)
1Aomori University, Aomori
2Budker Institute of Nuclear Physics, Novosibirsk
3Chuo University, Tokyo
4University of Cincinnati, Cincinnati, Ohio 45221
5University of Frankfurt, Frankfurt
6University of Hawaii, Honolulu, Hawaii 96822
7High Energy Accelerator Research Organization (KEK), Tsukuba
8Hiroshima Institute of Technology, Hiroshima
9Institute of High Energy Physics, Chinese Academy of Sciences, Beijing
10Institute of High Energy Physics, Vienna
11Institute for Theoretical and Experimental Physics, Moscow
12J. Stefan Institute, Ljubljana
13Kanagawa University, Yokohama
14Korea University, Seoul
15Kyoto University, Kyoto
16Kyungpook National University, Taegu
17Institut de Physique des Hautes Énergies, Université de Lausanne, Lausanne
18University of Ljubljana, Ljubljana
19University of Maribor, Maribor
20University of Melbourne, Victoria
21Nagoya University, Nagoya
22Nara Women’s University, Nara
23National Kaohsiung Normal University, Kaohsiung
24National Lien-Ho Institute of Technology, Miao Li
25National Taiwan University, Taipei
26H. Niewodniczanski Institute of Nuclear Physics, Krakow
27Nihon Dental College, Niigata
28Niigata University, Niigata
29Osaka City University, Osaka
30Osaka University, Osaka
31Panjab University, Chandigarh
32Peking University, Beijing
33Princeton University, Princeton, New Jersey 08545
34RIKEN BNL Research Center, Upton, New York 11973
35Saga University, Saga
36University of Science and Technology of China, Hefei
37Seoul National University, Seoul
38Sungkyunkwan University, Suwon
39University of Sydney, Sydney NSW
40Toho University, Funabashi
41Tohoku Gakuin University, Tagajo
42Tohoku University, Sendai
43University of Tokyo, Tokyo
44Tokyo Institute of Technology, Tokyo
45Tokyo Metropolitan University, Tokyo
46Tokyo University of Agriculture and Technology, Tokyo
47University of Tsukuba, Tsukuba
48Utkal University, Bhubaneswer
49Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
50Yokkaichi University, Yokkaichi
51Yonsei University, Seoul
52Gyeongsang National University, Chinju
53Chiba University, Chiba
Received 23 January 2003; published 7 July 2003
We present an improved measurement of CP-violating asymmetries in B0→π+π- decays based on a 78fb-1 data sample collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct one neutral B meson as a B0→π+π- CP eigenstate and identify the flavor of the accompanying B meson from inclusive properties of its decay products. We apply an unbinned maximum likelihood fit to the distribution of the time intervals between the two B meson decay points. The fit yields the CP-violating asymmetry amplitudes Aππ=+0.77±0.27(stat)±0.08(syst) and Sππ=-1.23±0.41(stat)-0.07+0.08(syst), where the statistical uncertainties are determined from the Monte Carlo pseudoexperiments. We obtain confidence intervals for CP-violating asymmetry parameters Aππ and Sππ based on a frequentist approach. We rule out the CP-conserving case, Aππ=Sππ=0, at the 99.93% confidence level. We discuss how these results constrain the value of the Cabibbo-Kobayashi-Maskawa (CKM) angle φ2.
© 2003 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevD.68.012001
DOI:
10.1103/PhysRevD.68.012001
PACS:
11.30.Er, 12.15.Hh, 13.25.Hw
*On leave from Nova Gorica Polytechnic, Nova Gorica.
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