Observation of DirectCPViolation inB0→π+π−Decays and Model-Independent Constraints on the Quark-Mixing Angleϕ2

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

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.

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