Observation of direct CP violation in B0→π+π- decays and model-independent constraints on the quark-mixing angle 2

H. Ishino, K. Abe, K. Abe, I. Adachi, H. Aihara, D. Anipko, K. Arinstein, T. Aushev, A. M. Bakich, E. Barberio, M. Barbero, I. Bedny, U. Bitenc, I. Bizjak, S. Blyth, A. Bozek, M. Bračko, T. E. Browder, M. C. Chang, P. ChangY. Chao, A. Chen, K. F. Chen, W. T. Chen, B. G. Cheon, R. Chistov, Y. Choi, Y. K. Choi, S. Cole, J. Dalseno, M. Dash, A. Drutskoy, S. Eidelman, S. Fratina, T. Gershon, A. Go, G. Gokhroo, B. Golob, A. Gorišek, H. Ha, J. Haba, K. Hara, K. Hayasaka, M. Hazumi, D. Heffernan, T. Hokuue, Y. Hoshi, S. Hou, Y. B. Hsiung, T. Iijima, A. Imoto, K. Inami, A. Ishikawa, Y. Iwasaki, J. H. Kang, P. Kapusta, S. U. Kataoka, N. Katayama, H. Kawai, T. Kawasaki, H. R. Khan, A. Kibayashi, H. Kichimi, K. Kinoshita, S. Korpar, P. Križan, P. Krokovny, R. Kulasiri, R. Kumar, C. C. Kuo, A. Kusaka, A. Kuzmin, Y. J. Kwon, M. J. Lee, S. E. Lee, T. Lesiak, A. Limosani, S. W. Lin, J. MacNaughton, F. Mandl, D. Marlow, T. Matsumoto, A. Matyja, S. McOnie, W. Mitaroff, K. Miyabayashi, H. Miyake, H. Miyata, Y. Miyazaki, R. Mizuk, D. Mohapatra, Y. Nagasaka, E. Nakano, M. Nakao, S. Nishida, O. Nitoh, T. Nozaki, S. Ogawa, T. Ohshima, S. L. Olsen, Y. Onuki, H. Ozaki, P. Pakhlov, G. Pakhlova, H. Park, L. S. Peak, R. Pestotnik, L. E. Piilonen, H. Sahoo, Y. Sakai, N. Satoyama, T. Schietinger, O. Schneider, J. Schümann, C. Schwanda, A. J. Schwartz, R. Seidl, K. Senyo, M. E. Sevior, H. Shibuya, B. Shwartz, A. Somov, N. Soni, S. Stanič, M. Starič, H. Stoeck, K. Sumisawa, T. Sumiyoshi, S. Y. Suzuki, O. Tajima, F. Takasaki, K. Tamai, N. Tamura, M. Tanaka, Y. Teramoto, X. C. Tian, K. Trabelsi, T. Tsukamoto, S. Uehara, K. Ueno, Y. Unno, S. Uno, P. Urquijo, Y. Ushiroda, Y. Usov, G. Varner, K. E. Varvell, S. Villa, C. H. Wang, M. Z. Wang, Y. Watanabe, E. Won, C. H. Wu, Q. L. Xie, B. D. Yabsley, A. Yamaguchi, Y. Yamashita, M. Yamauchi, L. M. Zhang, Z. P. Zhang, V. Zhilich, A. Zupanc

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Abstract

We report a new measurement of the time-dependent CP-violating parameters in B0→π+π- decays with 535×106 BB̄ pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider operating at the Υ(4S) resonance. We find 1464±65 B0→π+π- events and measure the CP-violating parameters Sππ=-0.61±0.10(stat)±0. 04(syst) and Aππ=+0.55±0.08(stat)±0.05(syst). We observe large direct CP violation with a significance greater than 5 standard deviations for any Sππ value. Using isospin relations, we measure the Cabibbo-Kobayashi-Maskawa quark-mixing matrix angle 2=(97±11)° for the solution consistent with the standard model and exclude the range 11°< 2<79° at the 95% confidence level.

Original languageEnglish
Article number211801
JournalPhysical review letters
Volume98
Issue number21
DOIs
Publication statusPublished - 2007 May 21

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Ishino, H., Abe, K., Abe, K., Adachi, I., Aihara, H., Anipko, D., Arinstein, K., Aushev, T., Bakich, A. M., Barberio, E., Barbero, M., Bedny, I., Bitenc, U., Bizjak, I., Blyth, S., Bozek, A., Bračko, M., Browder, T. E., Chang, M. C., ... Zupanc, A. (2007). Observation of direct CP violation in B0→π+π- decays and model-independent constraints on the quark-mixing angle 2. Physical review letters, 98(21), [211801]. https://doi.org/10.1103/PhysRevLett.98.211801