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

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

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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