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

Research output: Contribution to journalArticle

75 Citations (Scopus)

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

    Fingerprint

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

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