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Evidence for CP -violating asymmetries in B 0 → π + <mml:…

2003; American Physical Society; Volume: 68; Issue: 1 Linguagem: Inglês

10.1103/physrevd.68.012001

1538-4500

K. Abe, K. Abe, K. Abe, K. Abe, I. Adachi, H. Aihara, K. Akai, M. Akatsu, M. Akemoto, Y. Asano, T. Aushev, A. M. Bakich, Y. Ban, E. Banaś, A. Bay, I. Bedny, P. K. Behera, I. Bizjak, A. Bondar, A. Bożek, M. Bračko, J. Brodzicka, T. E. Browder, B. C. K. Casey, P. Chang, K. F. Chen, B. G. Cheon, R. Chistov, S. K. Choi, Y. Choi, Y. Choi, M. Danilov, J. Dragic, A. Drutskoy, S. Eidelman, V. Eiges, C.W. Everton, J. Flanagan, C. C. Kuo, K. Furukawa, N. Gabyshev, A. Garmash, T. J. Gershon, B. Golob, R. Guo, C. Hagner, K. Hara, N. C. Hastings, K. Hasuko, H. Hayashii, M. Hazumi, T. Higuchi, L. Hinz, T. Hojo, T. Hokuue, Y. Hoshi, W.-S. Hou, Y. Hsiung, Hsuan‐Cheng Huang, T. Igaki, Y. Igarashi, T. Iijima, H. Ikeda, K. Inami, A. Ishikawa, H. Ishino, R. Itoh, M. Iwasaki, M. Iwasaki, Hyejin Jang, J. S. Kang, P. Kapusta, S.U. Kataoka, N. Katayama, G. Katano, H. Kawai, N. Kawamura, T. Kawasaki, H. Kichimi, M. Kikuchi, E. Kikutani, D. W. Kim, Hyunwoo Kim, H. O. Kim, Hyunwoo Kim, J. H. Kim, S. K. Kim, S. Kobayashi, S. Korpar, P. Križan, P. Krokovny, T. Kubo, R. Kulasiri, S. Kumar, A. Kuzmin, Y.-J. Kwon, J. S. Lange, G. Leder, S. H. Lee, J. Li, S.-W. Lin, J. MacNaughton, F. Mandl, D. Marlow, S. Matsumoto, T. Matsumoto, S. Michizono, T. Mimashi, W. Mitaroff, K. Miyabayashi, H. Miyake, H. Miyata, G. R. Moloney, T. Mori, A. Murakami, Y. Nagasaka, T. Nakadaira, T. Nakamura, E. Nakano, M. Nakao, Hiroyuki Nakayama, J. W. Nam, K. Neichi, S. Nishida, O. Nitoh, S. Noguchi, T. Nozaki, S. Ogawa, Y. Ogawa, K. Ohmi, Y. Ohnishi, T. Ohshima, N. Ohuchi, T. Okabe, S. Okuno, S. L. Olsen, Y. Onuki, W. Ostrowicz, H. Ozaki, H. Pałka, C. W. Park, H. Park, K. S. Park, L.S. Peak, J.-P. Perroud, M. Peters, L. E. Piilonen, M. Różańska, K. Rybicki, H. Sagawa, Saburou Saitoh, Y. Sakai, T. Sarangi, M. Satapathy, A. Satpathy, O. Schneider, S. Schrenk, J. Schümann, C. Schwanda, S. Semenov, K. Senyo, M. E. Sevior, H. Shibuya, T. Shidara, B. Shwartz, V. Sidorov, J. B. Singh, S. Stanič, M. Starič, R. Sugahara, A. Sugiyama, K. Sumisawa, T. Sumiyoshi, K. Suzuki, S. Suzuki, T. Takahashi, F. Takasaki, K. Tamai, N. Tamura, J. Tanaka, M. Tanaka, M. Tawada, G. N. Taylor, Y. Teramoto, S. Tokuda, T. Tomura, K. Trabelsi, T. Tsuboyama, T. Tsukamoto, S. Uehara, Y. Unno, S. Uno, N. Uozaki, S. Vahsen, G. Varner, K. E. Varvell, C. C. Wang, C. H. Wang, J. G. Wang, M.-Z. Wang, Y. Watanabe, E. Won, B. Yabsley, Y. Yamada, A. Yamaguchi, H. Yamamoto, Y. Yamashita, Y. Yamashita, M. Yamauchi, M. Yokoyama, M. Yoshida, C. C. Zhang, Z. P. Zhang, V. Zhilich, D. Žontar,

Neutrino Physics Research

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)+0.08−0.07(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. Received 23 January 2003DOI:https://doi.org/10.1103/PhysRevD.68.012001©2003 American Physical Society