Observation of direct CP violation in B0 --> pi+pi- decays and model-independent constraints on the quark-mixing angle phi2

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 Bracko; T E Browder; M-C Chang; P Chang; Y 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 Gorisek; 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 Krizan; 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 Stanic; M Staric; 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; Belle Collaboration

doi:10.1103/PhysRevLett.98.211801

Observation of direct CP violation in B0 --> pi+pi- decays and model-independent constraints on the quark-mixing angle phi2

Phys Rev Lett. 2007 May 25;98(21):211801. doi: 10.1103/PhysRevLett.98.211801. Epub 2007 May 21.

Authors

H Ishino¹, 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 Bracko, T E Browder, M-C Chang, P Chang, Y 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 Gorisek, 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 Krizan, 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 Stanic, M Staric, 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; Belle Collaboration

Affiliation

¹ Tokyo Institute of Technology, Tokyo.

PMID: 17677763
DOI: 10.1103/PhysRevLett.98.211801

Abstract

We report a new measurement of the time-dependent CP-violating parameters in B(0)-->pi(+)pi(-) decays with 535 x 10(6) BB pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider operating at the Upsilon(4S) resonance. We find 1464+/-65 B(0)-->pi(+)pi(-) events and measure the CP-violating parameters S(pipi)=-0.61+/-0.10(stat)+/-0.04(syst) and A(pipi)=+0.55+/-0.08(stat)+/-0.05(syst). We observe large direct CP violation with a significance greater than 5 standard deviations for any S(pipi) value. Using isospin relations, we measure the Cabibbo-Kobayashi-Maskawa quark-mixing matrix angle phi(2)=(97+/-11) degrees for the solution consistent with the standard model and exclude the range 11 degrees <phi(2)<79 degrees at the 95% confidence level.