Measurements of Branching Fractions and Cp -violating Asymmetries in B

We present updated measurements of branching fractions and CP -violating asymmetries for neutral B meson decays to two-body final states of charged pions and kaons. The results are obtained from a data sample of about 60 million Υ (4S) → BB decays collected between 1999 and 2001 by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The sample contains 124 −15 ππ, 403± 24 Kπ, and 0.6 −7.4 KK candidates, from which we measure the following quantities: B(B → ππ) = (5.4 ± 0.7± 0.4) × 10, B(B → Kπ) = (17.8 ± 1.1± 0.8) × 10, B(B → KK) < 1.1× 10 (90%C.L.), AKπ = −0.05± 0.06 ± 0.01 [−0.14,+0.05] , Sππ = −0.01± 0.37 ± 0.07 [−0.66,+0.62] , Cππ = −0.02± 0.29 ± 0.07 [−0.54,+0.48] , where the errors are statistical and systematic, respectively, and the asymmetry limits correspond to the 90% confidence level. These results are preliminary. Presented at the 37th Rencontres de Moriond on Electroweak Interactions and Unified Theories, 3/9—3/16/2002, Les Arcs, Savoie, France Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309 Work supported in part by Department of Energy contract DE-AC03-76SF00515. The BABAR Collaboration, B. Aubert, D. Boutigny, J.-M. Gaillard, A. Hicheur, Y. Karyotakis, J. P. Lees, P. Robbe, V. Tisserand, A. Zghiche Laboratoire de Physique des Particules, F-74941 Annecy-le-Vieux, France A. Palano, A. Pompili Università di Bari, Dipartimento di Fisica and INFN, I-70126 Bari, Italy G. P. Chen, J. C. Chen, N. D. Qi, G. Rong, P. Wang, Y. S. Zhu Institute of High Energy Physics, Beijing 100039, China G. Eigen, I. Ofte, B. Stugu University of Bergen, Inst. of Physics, N-5007 Bergen, Norway G. S. Abrams, A. W. Borgland, A. B. Breon, D. N. Brown, J. Button-Shafer, R. N. Cahn, E. Charles, M. S. Gill, A. V. Gritsan, Y. Groysman, R. G. Jacobsen, R. W. Kadel, J. Kadyk, L. T. Kerth, Yu. G. Kolomensky, J. F. Kral, C. LeClerc, M. E. Levi, G. Lynch, L. M. Mir, P. J. Oddone, M. Pripstein, N. A. Roe, A. Romosan, M. T. Ronan, V. G. Shelkov, A. V. Telnov, W. A. Wenzel Lawrence Berkeley National Laboratory and University of California, Berkeley, CA 94720, USA T. J. Harrison, C. M. Hawkes, D. J. Knowles, S. W. O’Neale, R. C. Penny, A. T. Watson, N. K. Watson University of Birmingham, Birmingham, B15 2TT, United Kingdom T. Deppermann, K. Goetzen, H. Koch, B. Lewandowski, K. Peters, H. Schmuecker, M. Steinke Ruhr Universität Bochum, Institut für Experimentalphysik 1, D-44780 Bochum, Germany N. R. Barlow, W. Bhimji, N. Chevalier, P. J. Clark, W. N. Cottingham, B. Foster, C. Mackay, F. F. Wilson University of Bristol, Bristol BS8 1TL, United Kingdom K. Abe, C. Hearty, T. S. Mattison, J. A. McKenna, D. Thiessen University of British Columbia, Vancouver, BC, Canada V6T 1Z1 S. Jolly, A. K. McKemey Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom V. E. Blinov, A. D. Bukin, D. A. Bukin, A. R. Buzykaev, V. B. Golubev, V. N. Ivanchenko, A. A. Korol, E. A. Kravchenko, A. P. Onuchin, S. I. Serednyakov, Yu. I. Skovpen, A. N. Yushkov Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia D. Best, M. Chao, D. Kirkby, A. J. Lankford, M. Mandelkern, S. McMahon, D. P. Stoker University of California at Irvine, Irvine, CA 92697, USA K. Arisaka, C. Buchanan, S. Chun University of California at Los Angeles, Los Angeles, CA 90024, USA D. B. MacFarlane, S. Prell, Sh. Rahatlou, G. Raven, V. Sharma University of California at San Diego, La Jolla, CA 92093, USA C. Campagnari, B. Dahmes, P. A. Hart, N. Kuznetsova, S. L. Levy, O. Long, A. Lu, M. A. Mazur, J. D. Richman, W. Verkerke University of California at Santa Barbara, Santa Barbara, CA 93106, USA J. Beringer, A. M. Eisner, M. Grothe, C. A. Heusch, W. S. Lockman, T. Pulliam, T. Schalk, R. E. Schmitz, B. A. Schumm, A. Seiden, M. Turri, W. Walkowiak, D. C. Williams, M. G. Wilson University of California at Santa Cruz, Institute for Particle Physics, Santa Cruz, CA 95064, USA E. Chen, G. P. Dubois-Felsmann, A. Dvoretskii, D. G. Hitlin, S. Metzler, J. Oyang, F. C. Porter, A. Ryd, A. Samuel, S. Yang, R. Y. Zhu California Institute of Technology, Pasadena, CA 91125, USA S. Jayatilleke, G. Mancinelli, B. T. Meadows, M. D. Sokoloff University of Cincinnati, Cincinnati, OH 45221, USA T. Barillari, P. Bloom, W. T. Ford, U. Nauenberg, A. Olivas, P. Rankin, J. Roy, J. G. Smith, W. C. van Hoek, L. Zhang University of Colorado, Boulder, CO 80309, USA J. Blouw, J. L. Harton, M. Krishnamurthy, A. Soffer, W. H. Toki, R. J. Wilson, J. Zhang Colorado State University, Fort Collins, CO 80523, USA T. Brandt, J. Brose, T. Colberg, M. Dickopp, R. S. Dubitzky, A. Hauke, E. Maly, R. Müller-Pfefferkorn, S. Otto, K. R. Schubert, R. Schwierz, B. Spaan, L. Wilden Technische Universität Dresden, Institut für Kernund Teilchenphysik, D-01062 Dresden, Germany D. Bernard, G. R. Bonneaud, F. Brochard, J. Cohen-Tanugi, S. Ferrag, S. T’Jampens, Ch. Thiebaux, G. Vasileiadis, M. Verderi Ecole Polytechnique, LLR, F-91128 Palaiseau, France A. Anjomshoaa, R. Bernet, A. Khan, D. Lavin, F. Muheim, S. Playfer, J. E. Swain, J. Tinslay University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom M. Falbo Elon University, Elon College, NC 27244-2010, USA C. Borean, C. Bozzi, L. Piemontese Università di Ferrara, Dipartimento di Fisica and INFN, I-44100 Ferrara, Italy E. Treadwell Florida A&M University, Tallahassee, FL 32307, USA F. Anulli, R. Baldini-Ferroli, A. Calcaterra, R. de Sangro, D. Falciai, G. Finocchiaro, P. Patteri, I. M. Peruzzi, M. Piccolo, Y. Xie, A. Zallo Laboratori Nazionali di Frascati dell’INFN, I-00044 Frascati, Italy S. Bagnasco, A. Buzzo, R. Contri, G. Crosetti, M. Lo Vetere, M. Macri, M. R. Monge, S. Passaggio, F. C. Pastore, C. Patrignani, E. Robutti, A. Santroni, S. Tosi Università di Genova, Dipartimento di Fisica and INFN, I-16146 Genova, Italy 1 Also with Università di Perugia, I-06100 Perugia, Italy 2 Also with Università di Perugia, I-06100 Perugia, Italy M. Morii Harvard University, Cambridge, MA 02138, USA R. Bartoldus, R. Hamilton, U. Mallik University of Iowa, Iowa City, IA 52242, USA J. Cochran, H. B. Crawley, J. Lamsa, W. T. Meyer, E. I. Rosenberg, J. Yi Iowa State University, Ames, IA 50011-3160, USA G. Grosdidier, A. Höcker, H. M. Lacker, S. Laplace, F. Le Diberder, V. Lepeltier, A. M. Lutz, S. Plaszczynski, M. H. Schune, S. Trincaz-Duvoid, G. Wormser Laboratoire de l’Accélérateur Linéaire, F-91898 Orsay, France R. M. Bionta, V. Brigljević , D. J. Lange, M. Mugge, K. van Bibber, D. M. Wright Lawrence Livermore National Laboratory, Livermore, CA 94550, USA A. J. Bevan, J. R. Fry, E. Gabathuler, R. Gamet, M. George, M. Kay, D. J. Payne, R. J. Sloane, C. Touramanis University of Liverpool, Liverpool L69 3BX, United Kingdom M. L. Aspinwall, D. A. Bowerman, P. D. Dauncey, U. Egede, I. Eschrich, G. W. Morton, J. A. Nash, P. Sanders, D. Smith University of London, Imperial College, London, SW7 2BW, United Kingdom J. J. Back, G. Bellodi, P. Dixon, P. F. Harrison, R. J. L. Potter, H. W. Shorthouse, P. Strother, P. B. Vidal Queen Mary, University of London, E1 4NS, United Kingdom G. Cowan, S. George, M. G. Green, A. Kurup, C. E. Marker, T. R. McMahon, S. Ricciardi, F. Salvatore, G. Vaitsas University of London, Royal Holloway and Bedford New College, Egham, Surrey TW20 0EX, United Kingdom D. Brown, C. L. Davis University of Louisville, Louisville, KY 40292, USA J. Allison, R. J. Barlow, J. T. Boyd, A. C. Forti, F. Jackson, G. D. Lafferty, N. Savvas, J. H. Weatherall, J. C. Williams University of Manchester, Manchester M13 9PL, United Kingdom A. Farbin, A. Jawahery, V. Lillard, J. Olsen, D. A. Roberts, J. R. Schieck University of Maryland, College Park, MD 20742, USA G. Blaylock, C. Dallapiccola, K. T. Flood, S. S. Hertzbach, R. Kofler, V. B. Koptchev, T. B. Moore, H. Staengle, S. Willocq University of Massachusetts, Amherst, MA 01003, USA B. Brau, R. Cowan, G. Sciolla, F. Taylor, R. K. Yamamoto Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge, MA 02139, USA M. Milek, P. M. Patel McGill University, Montréal, QC, Canada H3A 2T8 F. Palombo, C. Vite Università di Milano, Dipartimento di Fisica and INFN, I-20133 Milano, Italy J. M. Bauer, L. Cremaldi, V. Eschenburg, R. Kroeger, J. Reidy, D. A. Sanders, D. J. Summers University of Mississippi, University, MS 38677, USA C. Hast, J. Y. Nief, P. Taras Université de Montréal, Laboratoire René J. A. Lévesque, Montréal, QC, Canada H3C 3J7 H. Nicholson Mount Holyoke College, South Hadley, MA 01075, USA C. Cartaro, N. Cavallo, G. De Nardo, F. Fabozzi, C. Gatto, L. Lista, P. Paolucci, D. Piccolo, C. Sciacca Università di Napoli Federico II, Dipartimento di Scienze Fisiche and INFN, I-80126, Napoli, Italy J. M. LoSecco University of Notre Dame, Notre Dame, IN 46556, USA J. R. G. Alsmiller, T. A. Gabriel Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA J. Brau, R. Frey, E. Grauges , M. Iwasaki, C. T. Potter, N. B. Sinev, D. Strom University of Oregon, Eugene, OR 97403, USA F. Colecchia, F. Dal Corso, A. Dorigo, F. Galeazzi, M. Margoni, M. Morandin, M. Posocco, M. Rotondo, F. Simonetto, R. Stroili, E. Torassa, C. Voci Università di Padova, Dipartimento di Fisica and INFN, I-35131 Padova, Italy M. Benayoun, H. Briand, J. Chauveau, P. David, Ch. de la Vaissière, L. Del Buono, O. Hamon, Ph. Leruste, J. Ocariz, M. Pivk, L. Roos, J. Stark Universités Paris VI et VII, Lab de Physique Nucléaire H. E., F-75252 Paris, France P. F. Manfredi, V. Re, V. Speziali Università di Pavia, Dipartimento di Elettronica and INFN, I-27100 Pavia, Italy E. D. Frank, L. Gladney, Q. H. Guo, J. Panetta University of Pennsylvania, Philadelphia, PA 19104, USA C. Angelini, G. Batignani, S. Bettarini, M. Bondioli, F. Bucci, E. Campagna, M. Carpinelli, F. Forti, M. A. Giorgi, A. Lusiani, G. Marchiori, F. Martinez-Vidal, M. Morganti, N. Neri, E. Paoloni, M. Rama, G. Rizzo, F. Sandrelli, G. Simi, G. Triggiani, J. Walsh Università di Pisa, Scuola Normale Superiore and INFN, I-56010 Pisa, Italy M. Haire, D. Judd, K. Paick, L. Turnbull, D. E. Wagoner Prairie View A&M University, Prairie View, TX 77446, USA J. Albert, P. Elmer, C. Lu, V. Miftakov, S. F. Schaffner, A. J. S. Smith, A. Tumanov, E. W. Varnes Princeton University, Princeton, NJ 08544, USA 3 Also with Università della Basilicata, I-85100 Potenza, Italy F. Bellini, G. Cavoto, D. del Re, R. Faccini, F. Ferrarotto, F. Ferroni, M. A. Mazzoni, S. Morganti, G. Piredda, M. Serra, C. Voena Università di Roma La Sapienza, Dipartimento di Fisica and INFN, I-00185 Roma, Italy S. Christ, R. Waldi Universität Rostock, D-18051 Rostock, Germany T. Adye, N. De Groot, B. Franek, N. I. Geddes, G. P. Gopal, S. M. Xella Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, United Kingdom R. Aleksan, S. Emery, A. Gaidot, S. F. Ganzhur, P.-F. Giraud, G. Hamel de Monchenault, W. Kozanecki, M. Langer, G. W. London, B. Mayer, B. Serfass, G. Vasseur, Ch. Yèche, M. Zito DAPNIA, Commissariat à l’Energie Atomique/Saclay, F-91191 Gif-sur-Yvette, France M. V. Purohit, A. W. Weidemann, F. X. Yumiceva University of South Carolina, Columbia, SC 29208, USA I. Adam, D. Aston, N. Berger, A. M. Boyarski, G. Calderini, M. R. Convery, D. P. Coupal, D. Dong, J. Dorfan, W. Dunwoodie, R. C. Field, T. Glanzman, S. J. Gowdy, T. Haas, T. Hadig, V. Halyo, T. Himel, T. Hryn’ova, M. E. Huffer, W. R. Innes, C. P. Jessop, M. H. Kelsey, P. Kim, M. L. Kocian, U. Langenegger, D. W. G. S. Leith, S. Luitz, V. Luth, H. L. Lynch, H. Marsiske, S. Menke, R. Messner, D. R. Muller, C. P. O’Grady, V. E. Ozcan, A. Perazzo, M. Perl, S. Petrak, H. Quinn, B. N. Ratcliff, S. H. Robertson, A. Roodman, A. A. Salnikov, T. Schietinger, R. H. Schindler, J. Schwiening, A. Snyder, A. Soha, S. M. Spanier, J. Stelzer, D. Su, M. K. Sullivan, H. A. Tanaka, J. Va’vra, S. R. Wagner, M. Weaver, A. J. R. Weinstein, W. J. Wisniewski, D. H. Wright, C. C. Young Stanford Linear Accelerator Center, Stanford, CA 94309, USA P. R. Burchat, C. H. Cheng, T. I. Meyer, C. Roat Stanford University, Stanford, CA 94305-4060, USA R. Henderson TRIUMF, Vancouver, BC, Canada V6T 2A3 W. Bugg, H. Cohn University of Tennessee, Knoxville, TN 37996, USA J. M. Izen, I. Kitayama, X. C. Lou University of Texas at Dallas, Richardson, TX 75083, USA F. Bianchi, M. Bona, D. Gamba Università di Torino, Dipartimento di Fisica Sperimentale and INFN, I-10125 Torino, Italy L. Bosisio, G. Della Ricca, S. Dittongo, L. Lanceri, P. Poropat, L. Vitale, G. Vuagnin Università di Trieste, Dipartimento di Fisica and INFN, I-34127 Trieste, Italy R. S. Panvini Vanderbilt University, Nashville, TN 37235, USA 4 Also with University of California at San Diego, La Jolla, CA 92093, USA C. M. Brown, P. D. Jackson, R. Kowalewski, J. M. Roney University of Victoria, Victoria, BC, Canada V8W 3P6 H. R. Band, S. Dasu, M. Datta, A. M. Eichenbaum, H. Hu, J. R. Johnson, R. Liu, F. Di Lodovico, Y. Pan, R. Prepost, I. J. Scott, S. J. Sekula, J. H. von Wimmersperg-Toeller, S. L. Wu, Z. Yu University of Wisconsin, Madison, WI 53706, USA T. M. B. Kordich, H. Neal Yale University, New Haven, CT 06511, USA Recent measurements of the CP -violating asymmetry parameter sin2β by the BABAR [1] and Belle [2] collaborations established CP violation in the B0 system. These measurements, as well as an updated result by BABAR [3] reported at this conference, are consistent with the Standard Model expectation based on measurements and theoretical estimates of the elements of the CabibboKobayashi-Maskawa [4] (CKM) quark-mixing matrix. The study of B decays to charmless hadronic two-body final states will yield important information about the remaining angles (α and γ) of the Unitarity Triangle. In the Standard Model, the time-dependent CP -violating asymmetry in the decay B0 → π+π− is related to the angle α, and ratios of branching fractions for various ππ and Kπ decay modes are sensitive to the angle γ. In this paper, we update our previous measurements of branching fractions [5] and CP -violating asymmetries [6] in B0 → π+π−, K+π−, and K+K− decays1 using a sample of 60 million BB pairs. We reconstruct a sample of B mesons (Brec) decaying to the h +h′− final state, where h and h′ refer to π or K, and examine the remaining charged particles in each event to “tag” the flavor of the other B meson (Btag). The decay rate distribution f+ (f−) when h +h′− = π+π− and Btag = B 0 (B0) is given by f±(∆t) = e−|∆t|/τ 4τ [1± Sππ sin(∆md∆t)∓ Cππ cos(∆md∆t)], (1) where τ is the mean B0 lifetime, ∆md is the eigenstate mass difference, and ∆t = trec − ttag is the time between the Brec and Btag decays. The CP -violating parameters Sππ and Cππ are defined as Sππ = 2Imλ 1 + |λ| and Cππ = 1− |λ| 1 + |λ| . (2) If the decay proceeds purely through the b → uW− tree process, then λ is given by λ(B → ππ) = ( V ∗ tbVtd VtbV ∗ td )( V ∗ udVub VudV ∗ ub )