B#[superscript 0]→J/#K[superscript *0]
and B[superscript 0]→J/#[superscript *0]
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Citation
Aubert, B. et al. “Bound on the Ratio of Decay Amplitudes for
B¯0→J/ψK*0 and B0→J/ψK*0.” Physical Review Letters 93.8 (2004):
Web. 18 May 2012. © 2004 American Physical Society
As Published
http://dx.doi.org/10.1103/PhysRevLett.93.081801
Publisher
American Physical Society
Version
Final published version
Citable link
http://hdl.handle.net/1721.1/70881
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Article is made available in accordance with the publisher's
policy and may be subject to US copyright law. Please refer to the
publisher's site for terms of use.
Bound on the Ratio of Decay Amplitudes for B
0! J= K
0and B
0! J= K
0B. Aubert,1R. Barate,1D. Boutigny,1F. Couderc,1J.-M. Gaillard,1A. Hicheur,1Y. Karyotakis,1J. P. Lees,1V. Tisserand,1 A. Zghiche,1A. Palano,2A. Pompili,2J. C. Chen,3N. D. Qi,3G. Rong,3P. Wang,3Y. S. Zhu,3G. Eigen,4I. Ofte,4 B. Stugu,4G. S. Abrams,5A.W. Borgland,5A. B. Breon,5D. N. Brown,5J. Button-Shafer,5R. N. Cahn,5E. Charles,5
C. T. Day,5M. S. Gill,5A.V. Gritsan,5Y. Groysman,5R. G. Jacobsen,5R.W. Kadel,5J. Kadyk,5L. T. Kerth,5 Yu. G. Kolomensky,5G. Kukartsev,5G. Lynch,5L. M. Mir,5P. J. Oddone,5T. J. Orimoto,5M. Pripstein,5N. A. Roe,5 M. T. Ronan,5V. G. Shelkov,5W. A. Wenzel,5K. E. Ford,6T. J. Harrison,6C. M. Hawkes,6S. E. Morgan,6A. T. Watson,6 M. Fritsch,7K. Goetzen,7T. Held,7H. Koch,7B. Lewandowski,7M. Pelizaeus,7M. Steinke,7J. T. Boyd,8N. Chevalier,8 W. N. Cottingham,8M. P. Kelly,8T. E. Latham,8F. F. Wilson,8T. Cuhadar-Donszelmann,9C. Hearty,9N. S. Knecht,9 T. S. Mattison,9J. A. McKenna,9D. Thiessen,9A. Khan,10P. Kyberd,10L. Teodorescu,10V. E. Blinov,11A. D. Bukin,11
V. P. Druzhinin,11V. B. Golubev,11V. N. Ivanchenko,11E. A. Kravchenko,11A. P. Onuchin,11S. I. Serednyakov,11 Yu. I. Skovpen,11E. P. Solodov,11A. N. Yushkov,11D. Best,12M. Bruinsma,12M. Chao,12I. Eschrich,12D. Kirkby,12 A. J. Lankford,12M. Mandelkern,12R. K. Mommsen,12W. Roethel,12D. P. Stoker,12C. Buchanan,13B. L. Hartfiel,13
J.W. Gary,14B. C. Shen,14K. Wang,14D. del Re,15H. K. Hadavand,15E. J. Hill,15D. B. MacFarlane,15H. P. Paar,15 Sh. Rahatlou,15V. Sharma,15J.W. Berryhill,16C. Campagnari,16B. Dahmes,16S. L. Levy,16O. Long,16A. Lu,16
M. A. Mazur,16J. D. Richman,16W. Verkerke,16T.W. Beck,17A. M. Eisner,17C. A. Heusch,17 W. S. Lockman,17 T. Schalk,17R. E. Schmitz,17B. A. Schumm,17A. Seiden,17 P. Spradlin,17D. C. Williams,17M. G. Wilson,17J. Albert,18 E. Chen,18G. P. Dubois-Felsmann,18A. Dvoretskii,18D. G. Hitlin,18I. Narsky,18T. Piatenko,18F. C. Porter,18A. Ryd,18
A. Samuel,18S. Yang,18S. Jayatilleke,19G. Mancinelli,19B. T. Meadows,19M. D. Sokoloff,19T. Abe,20F. Blanc,20 P. Bloom,20S. Chen,20W. T. Ford,20U. Nauenberg,20A. Olivas,20P. Rankin,20J. G. Smith,20J. Zhang,20L. Zhang,20 A. Chen,21J. L. Harton,21A. Soffer,21W. H. Toki,21R. J. Wilson,21Q. L. Zeng,21D. Altenburg,22T. Brandt,22J. Brose,22
T. Colberg,22M. Dickopp,22E. Feltresi,22A. Hauke,22H. M. Lacker,22E. Maly,22R. Mu¨ller-Pfefferkorn,22 R. Nogowski,22S. Otto,22A. Petzold,22J. Schubert,22K. R. Schubert,22R. Schwierz,22B. Spaan,22J. E. Sundermann,22
D. Bernard,23G. R. Bonneaud,23F. Brochard,23P. Grenier,23S. Schrenk,23Ch. Thiebaux,23G. Vasileiadis,23 M. Verderi,23D. J. Bard,24P. J. Clark,24D. Lavin,24F. Muheim,24S. Playfer,24Y. Xie,24M. Andreotti,25V. Azzolini,25
D. Bettoni,25C. Bozzi,25R. Calabrese,25G. Cibinetto,25E. Luppi,25M. Negrini,25L. Piemontese,25A. Sarti,25 E. Treadwell,26R. Baldini-Ferroli,27A. Calcaterra,27R. de Sangro,27G. Finocchiaro,27P. Patteri,27M. Piccolo,27
A. Zallo,27A. Buzzo,28R. Capra,28R. Contri,28G. Crosetti,28M. Lo Vetere,28M. Macri,28M. R. Monge,28 S. Passaggio,28C. Patrignani,28E. Robutti,28A. Santroni,28S. Tosi,28S. Bailey,29G. Brandenburg,29M. Morii,29
E. Won,29R. S. Dubitzky,30U. Langenegger,30W. Bhimji,31D. A. Bowerman,31P. D. Dauncey,31U. Egede,31 J. R. Gaillard,31G.W. Morton,31J. A. Nash,31G. P. Taylor,31M. J. Charles,32G. J. Grenier,32U. Mallik,32J. Cochran,33
H. B. Crawley,33J. Lamsa,33W. T. Meyer,33S. Prell,33E. I. Rosenberg,33J. Yi,33M. Davier,34G. Grosdidier,34 A. Ho¨cker,34S. Laplace,34F. Le Diberder,34V. Lepeltier,34A. M. Lutz,34T. C. Petersen,34S. Plaszczynski,34 M. H. Schune,34L. Tantot,34G. Wormser,34C. H. Cheng,35D. J. Lange,35M. C. Simani,35D. M. Wright,35A. J. Bevan,36
J. P. Coleman,36J. R. Fry,36E. Gabathuler,36R. Gamet,36R. J. Parry,36D. J. Payne,36R. J. Sloane,36C. Touramanis,36 J. J. Back,37C. M. Cormack,37P. F. Harrison,37,* G. B. Mohanty,37C. L. Brown,38G. Cowan,38R. L. Flack,38 H. U. Flaecher,38M. G. Green,38C. E. Marker,38T. R. McMahon,38S. Ricciardi,38F. Salvatore,38G. Vaitsas,38 M. A. Winter,38D. Brown,39C. L. Davis,39J. Allison,40N. R. Barlow,40R. J. Barlow,40P. A. Hart,40M. C. Hodgkinson,40
G. D. Lafferty,40A. J. Lyon,40J. C. Williams,40A. Farbin,41W. D. Hulsbergen,41A. Jawahery,41D. Kovalskyi,41 C. K. Lae,41V. Lillard,41D. A. Roberts,41G. Blaylock,42C. Dallapiccola,42K. T. Flood,42S. S. Hertzbach,42R. Kofler,42
V. B. Koptchev,42T. B. Moore,42S. Saremi,42H. Staengle,42S. Willocq,42R. Cowan,43G. Sciolla,43F. Taylor,43 R. K. Yamamoto,43D. J. J. Mangeol,44P. M. Patel,44S. H. Robertson,44A. Lazzaro,45F. Palombo,45J. M. Bauer,46 L. Cremaldi,46V. Eschenburg,46R. Godang,46R. Kroeger,46J. Reidy,46D. A. Sanders,46D. J. Summers,46H.W. Zhao,46 S. Brunet,47D. Coˆte´,47P. Taras,47H. Nicholson,48N. Cavallo,49F. Fabozzi,49,†C. Gatto,49L. Lista,49D. Monorchio,49
P. Paolucci,49D. Piccolo,49C. Sciacca,49M. Baak,50H. Bulten,50G. Raven,50L. Wilden,50C. P. Jessop,51 J. M. LoSecco,51T. A. Gabriel,52T. Allmendinger,53B. Brau,53K. K. Gan,53K. Honscheid,53D. Hufnagel,53H. Kagan,53
R. Kass,53T. Pulliam,53A. M. Rahimi,53R. Ter-Antonyan,53Q. K. Wong,53J. Brau,54R. Frey,54O. Igonkina,54 C. T. Potter,54N. B. Sinev,54D. Strom,54E. Torrence,54F. Colecchia,55A. Dorigo,55F. Galeazzi,55M. Margoni,55 M. Morandin,55M. Posocco,55M. Rotondo,55F. Simonetto,55R. Stroili,55G. Tiozzo,55C. Voci,55M. Benayoun,56
H. Briand,56J. Chauveau,56P. David,56Ch. de la Vaissie`re,56L. Del Buono,56O. Hamon,56M. J. J. John,56Ph. Leruste,56 J. Malcles,56J. Ocariz,56M. Pivk,56L. Roos,56S. T’Jampens,56G. Therin,56P. F. Manfredi,57V. Re,57P. K. Behera,58 L. Gladney,58Q. H. Guo,58J. Panetta,58F. Anulli,27,59M. Biasini,59I. M. Peruzzi,27,59M. Pioppi,59C. Angelini,60 G. Batignani,60S. Bettarini,60M. Bondioli,60F. Bucci,60G. Calderini,60M. Carpinelli,60V. Del Gamba,60F. Forti,60 M. A. Giorgi,60A. Lusiani,60G. Marchiori,60F. Martinez-Vidal,60,‡M. Morganti,60N. Neri,60E. Paoloni,60M. Rama,60 G. Rizzo,60F. Sandrelli,60J. Walsh,60M. Haire,61D. Judd,61K. Paick,61D. E. Wagoner,61N. Danielson,62P. Elmer,62 Y. P. Lau,62C. Lu,62V. Miftakov,62J. Olsen,62A. J. S. Smith,62A.V. Telnov,62F. Bellini,63G. Cavoto,62,63R. Faccini,63
F. Ferrarotto,63F. Ferroni,63M. Gaspero,63L. Li Gioi,63M. A. Mazzoni,63S. Morganti,63M. Pierini,63G. Piredda,63 F. Safai Tehrani,63C. Voena,63S. Christ,64G. Wagner,64R. Waldi,64T. Adye,65N. De Groot,65B. Franek,65 N. I. Geddes,65G. P. Gopal,65E. O. Olaiya,65R. Aleksan,66S. Emery,66A. Gaidot,66S. F. Ganzhur,66P.-F. Giraud,66 G. Hamel de Monchenault,66W. Kozanecki,66M. Langer,66M. Legendre,66G.W. London,66B. Mayer,66G. Schott,66 G. Vasseur,66Ch. Ye`che,66M. Zito,66M.V. Purohit,67A.W. Weidemann,67J. R. Wilson,67F. X. Yumiceva,67D. Aston,68 R. Bartoldus,68N. Berger,68A. M. Boyarski,68O. L. Buchmueller,68M. R. Convery,68M. Cristinziani,68G. De Nardo,68
D. Dong,68J. Dorfan,68D. Dujmic,68W. Dunwoodie,68E. E. Elsen,68S. Fan,68R. C. Field,68T. Glanzman,68 S. J. Gowdy,68T. Hadig,68V. Halyo,68C. Hast,68T. Hryn’ova,68W. R. Innes,68M. H. Kelsey,68P. Kim,68M. L. Kocian,68
D.W. G. S. Leith,68J. Libby,68S. Luitz,68V. Luth,68H. L. Lynch,68H. Marsiske,68R. Messner,68D. R. Muller,68 C. P. O’Grady,68V. E. Ozcan,68A. Perazzo,68M. Perl,68S. Petrak,68B. N. Ratcliff,68A. Roodman,68A. A. Salnikov,68 R. H. Schindler,68J. Schwiening,68G. Simi,68A. Snyder,68A. Soha,68J. Stelzer,68D. Su,68M. K. Sullivan,68J. Va’vra,68
S. R. Wagner,68M. Weaver,68A. J. R. Weinstein,68W. J. Wisniewski,68M. Wittgen,68D. H. Wright,68A. K. Yarritu,68 C. C. Young,68P. R. Burchat,69A. J. Edwards,69T. I. Meyer,69B. A. Petersen,69C. Roat,69S. Ahmed,70M. S. Alam,70
J. A. Ernst,70M. A. Saeed,70M. Saleem,70F. R. Wappler,70W. Bugg,71M. Krishnamurthy,71S. M. Spanier,71 R. Eckmann,72H. Kim,72J. L. Ritchie,72A. Satpathy,72R. F. Schwitters,72J. M. Izen,73I. Kitayama,73X. C. Lou,73
S. Ye,73F. Bianchi,74M. Bona,74F. Gallo,74D. Gamba,74C. Borean,75L. Bosisio,75C. Cartaro,75 F. Cossutti,75 G. Della Ricca,75S. Dittongo,75S. Grancagnolo,75L. Lanceri,75P. Poropat,75,xL. Vitale,75G. Vuagnin,75R. S. Panvini,76 Sw. Banerjee,77C. M. Brown,77D. Fortin,77P. D. Jackson,77R. Kowalewski,77J. M. Roney,77H. R. Band,78S. Dasu,78
M. Datta,78A. M. Eichenbaum,78M. Graham,78J. J. Hollar,78J. R. Johnson,78P. E. Kutter,78H. Li,78R. Liu,78 F. Di Lodovico,78A. Mihalyi,78A. K. Mohapatra,78Y. Pan,78R. Prepost,78A. E. Rubin,78S. J. Sekula,78P. Tan,78
J. H. von Wimmersperg-Toeller,78J. Wu,78S. L. Wu,78Z. Yu,78M. G. Greene,79and H. Neal79 (The BABARCollaboration)
1Laboratoire de Physique des Particules, F-74941 Annecy-le-Vieux, France 2Universita` di Bari, Dipartimento di Fisica and INFN, I-70126 Bari, Italy
3Institute of High Energy Physics, Beijing 100039, China 4University of Bergen, Institute of Physics, N-5007 Bergen, Norway
5Lawrence Berkeley National Laboratory and University of California, Berkeley, California 94720, USA 6University of Birmingham, Birmingham, B15 2TT, United Kingdom
7Ruhr Universita¨t Bochum, Institut fu¨r Experimentalphysik 1, D-44780 Bochum, Germany 8University of Bristol, Bristol BS8 1TL, United Kingdom
9University of British Columbia, Vancouver, British Columbia V6T 1Z1 Canada 10Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom
11Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia 12University of California at Irvine, Irvine, California 92697, USA 13University of California at Los Angeles, Los Angeles, California 90024, USA
14University of California at Riverside, Riverside, California 92521, USA 15University of California at San Diego, La Jolla, California 92093, USA 16University of California at Santa Barbara, Santa Barbara, California 93106, USA
17University of California at Santa Cruz, Institute for Particle Physics, Santa Cruz, California 95064, USA 18California Institute of Technology, Pasadena, California 91125, USA
19University of Cincinnati, Cincinnati, Ohio 45221, USA 20University of Colorado, Boulder, Colorado 80309, USA 21Colorado State University, Fort Collins, Colorado 80523, USA
22Technische Universita¨t Dresden, Institut fu¨r Kern- und Teilchenphysik, D-01062 Dresden, Germany 23Ecole Polytechnique, LLR, F-91128 Palaiseau, France
24University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
25Universita` di Ferrara, Dipartimento di Fisica and INFN, I-44100 Ferrara, Italy 26Florida A&M University, Tallahassee, Florida 32307, USA
27Laboratori Nazionali di Frascati dell’INFN, I-00044 Frascati, Italy 28Universita` di Genova, Dipartimento di Fisica and INFN, I-16146 Genova, Italy
29Harvard University, Cambridge, Massachusetts 02138, USA
30Universita¨t Heidelberg, Physikalisches Institut, Philosophenweg 12, D-69120 Heidelberg, Germany 31Imperial College London, London, SW7 2AZ, United Kingdom
32University of Iowa, Iowa City, Iowa 52242, USA 33Iowa State University, Ames, Iowa 50011-3160, USA 34Laboratoire de l’Acce´le´rateur Line´aire, F-91898 Orsay, France 35Lawrence Livermore National Laboratory, Livermore, California 94550, USA
36University of Liverpool, Liverpool L69 72E, United Kingdom 37Queen Mary, University of London, E1 4NS, United Kingdom
38University of London, Royal Holloway and Bedford New College, Egham, Surrey TW20 0EX, United Kingdom 39University of Louisville, Louisville, Kentucky 40292, USA
40University of Manchester, Manchester M13 9PL, United Kingdom 41University of Maryland, College Park, Maryland 20742, USA 42University of Massachusetts, Amherst, Massachusetts 01003, USA
43Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge, Massachusetts 02139, USA 44McGill University, Montre´al, Quebec H3A 2T8 Canada
45Universita` di Milano, Dipartimento di Fisica and INFN, I-20133 Milano, Italy 46University of Mississippi, University, Mississippi 38677, USA
47Universite´ de Montre´al, Laboratoire Rene´ J. A. Le´vesque, Montre´al, Quebec H3C 3J7, Canada 48Mount Holyoke College, South Hadley, Massachusetts 01075, USA
49Universita` di Napoli Federico II, Dipartimento di Scienze Fisiche and INFN, I-80126, Napoli, Italy
50NIKHEF, National Institute for Nuclear Physics and High Energy Physics, NL-1009 DB Amsterdam, The Netherlands 51University of Notre Dame, Notre Dame, Indiana 46556, USA
52Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA 53The Ohio State University, Columbus, Ohio 43210, USA
54University of Oregon, Eugene, Oregon 97403, USA
55Universita` di Padova, Dipartimento di Fisica and INFN, I-35131 Padova, Italy
56Universite´s Paris VI et VII, Laboratoire de Physique Nucle´aire et de Hautes Energies, F-75252 Paris, France 57Universita` di Pavia, Dipartimento di Elettronica and INFN, I-27100 Pavia, Italy
58University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA 59Universita` di Perugia, Dipartimento di Fisica and INFN, I-06100 Perugia, Italy
60Universita` di Pisa, Dipartimento di Fisica, Scuola Normale Superiore and INFN, I-56127 Pisa, Italy 61Prairie View A&M University, Prairie View, Texas 77446, USA
62Princeton University, Princeton, New Jersey 08544, USA
63Universita` di Roma La Sapienza, Dipartimento di Fisica and INFN, I-00185 Roma, Italy 64Universita¨t Rostock, D-18051 Rostock, Germany
65Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, United Kingdom 66DSM/Dapnia, CEA/Saclay, F-91191 Gif-sur-Yvette, France
67University of South Carolina, Columbia, South Carolina 29208, USA 68Stanford Linear Accelerator Center, Stanford, California 94309, USA
69Stanford University, Stanford, California 94305-4060, USA 70State University of New York, Albany, New York 12222, USA 71University of Tennessee, Knoxville, Tennessee 37996, USA
72University of Texas at Austin, Austin, Texas 78712, USA 73University of Texas at Dallas, Richardson, Texas 75083, USA
74Universita` di Torino, Dipartimento di Fisica Sperimentale and INFN, I-10125 Torino, Italy 75Universita` di Trieste, Dipartimento di Fisica and INFN, I-34127 Trieste, Italy
76Vanderbilt University, Nashville, Tennessee 37235, USA 77University of Victoria, Victoria, British Columbia V8W 3P6, Canada
78University of Wisconsin, Madison, Wisconsin 53706, USA 79Yale University, New Haven, Connecticut 06511, USA
(Received 3 April 2004; published 18 August 2004)
We have measured the time-dependent decay rate for the process B ! J= K0892 in a sample of
about 88 106 4S ! BB decays collected with the BABAR detector at the PEP-II
asymmetric-energy B factory at SLAC. In this sample we study flavor-tagged events in which one neutral B meson is reconstructed in the J= K0or J= K0final state. We measure the coefficients of the cosine and sine
terms in the time-dependent asymmetries for J= K0and J= K0, find them to be consistent with the standard model expectations, and set upper limits at 90% confidence level (C.L.) on the decay amplitude ratios jAB0! J= K0j=jAB0! J= K0j < 0:26 and jAB0! J= K0j=jAB0! J= K0j < 0:32.
For a single ratio of wrong-flavor to favored amplitudes for B0 and B0combined, we obtain an upper
limit of 0.25 at 90% C.L.
DOI: 10.1103/PhysRevLett.93.081801 PACS numbers: 13.25.Hw, 11.30.Er, 12.15.Hh
The standard model of electroweak interactions de-scribes CP violation in weak interactions of quarks by the presence of a complex phase in the three-generation Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing ma-trix [1]. In this framework, the CP asymmetries in the proper-time distributions of neutral B decays to J= K0
S
and J= K0
L are directly related to the CP-violation
pa-rameter sin2 [2]. The time-dependent CP asymmetries for J= K0
Sand J= KL0 are of opposite sign and, to a very
good approximation, equal in magnitude [3]. The decay
B0 ! J= K0
S(B0! J= KL0) proceeds through the
CKM-favored, color-suppressed decay B0! J= K0 [4]
fol-lowed by K0 ! K0
S (K0! K0L). The so-called
wrong-flavor B0 decay amplitude to the opposite strangeness
final state B0! J= K0 is expected to be negligible in
the standard model [3]. Interference between a wrong-flavor amplitude and the favored amplitude can alter the relation between the CP asymmetries, ACP, for the
J= K0
S and J= K0L final states. In general, a difference
between ACPJ= K0
S and ACPJ= KL0 of more than a
few times 103requires a wrong-flavor amplitude [3]. A limit on the CP-odd part of the phase difference between the wrong-flavor amplitude and the favored amplitude can be derived from the measured values of sin2 from
Bdecays to the J= K0
Sand J= KL0 final states. No test of
the modulus of the wrong-flavor amplitude currently exists.
The decay mode B0 ! J= K0 proceeds via the same
quark transition as B0 ! J= K0. The matrix elements,
and therefore the ratio of wrong-flavor to favored ampli-tudes, are expected to be similar for B0! J= K0 and
B0 ! J= K0[3]. In this Letter we present a measurement
of the ratio of wrong-flavor to favored amplitude for the decay B0 ! J= K0, from the time-dependent
asymme-try, where we use K0! K
to identify the strange-ness of the final state. The data sample consists of about 88 106 BBpairs produced in e e interactions at the
4S resonance, corresponding to an integrated lumi-nosity of 82 fb1, collected with the BABAR detector [5] at the PEP-II asymmetric-energy collider at SLAC.
Charged particles are detected, and their momenta measured, by a combination of a vertex tracker consisting of five layers of double-sided silicon microstrip detectors, and a 40-layer central drift chamber, both operating in the 1.5-T magnetic field of a superconducting solenoid. We identify photons and electrons using a CsI(Tl) electro-magnetic calorimeter. Further charged particle identifi-cation is provided by the average energy loss (dE=dx) in
the tracking devices and by an internally reflecting ring imaging Cherenkov detector covering the central region. Muons are identified by their penetration through the iron plates of a magnet flux return.
The analysis method is similar to that of other time-dependent mixing measurements performed at BABAR [6]. We use a sample of events (BJ= K) in which one
neutral B meson is reconstructed in the state J= K0 or
J= K0. The J= meson is reconstructed through its decay to e e or , and the K0 (K0) meson through its decay to K (K ). We examine each event in this sample for evidence that the other B meson decayed either as a B0or B0 (flavor tag).
The pseudoscalar to vector-vector decay B0!
J= K0892 is described by three amplitudes, A0, Ak,
and A?, for the longitudinal, parallel, and perpendicular
transverse polarization [7], respectively, of the vector mesons. In the selection of B0 ! J= K0892 there is a
small contribution from B0! J= K
01430, whose
de-cay amplitude is denoted with As. The favored decay amplitudes AB0! J= K
aeiae ia are
de-scribed by the magnitudes a, weak phase a, and strong
phases a
, where 0; k; ?; s. The amplitudes for the
wrong-flavor decays are given by AB0 ! J= K
bei b
e ib. The corresponding decay amplitudes for the
charge-conjugate final state J= K are obtained by replacing a with a, b
with b, bwith b, and b
with b. We assume a a.
The proper-time distributions of B meson decays to
J= K (J= K ), having either a B0or B0 tag, can
be expressed in terms of the B0-B0 oscillation amplitude and the amplitudes describing B0 and B0 decays to this
final state [8]. The angular-integrated decay rate f f to
the final state J= K when the tagging meson is a
B0B0 is given by f t ejtj= B0 4 B0 1 C cosmdt S sinmdt; (1)
where t trec ttagis the difference between the proper decay times of the reconstructed B meson (Brec) and the
tagging B meson (Btag), B0 is the B0lifetime, and mdis the B0-B0oscillation frequency. The corresponding decay
rates f and f for the charge-conjugate final state
J= K are obtained by replacing C with C and S with S.
The C and S coefficients are related to the wrong-flavor and favored amplitudes by
C a 2 b2 a2 b2; and S 2P absin a2 b2 ; (2) with a2 a2 0 a2k a2? a2s, b2 b20 b2k b2? b2s,
and 11 for 0; k; s?. The strong and weak phase differences are given by b
a and
argq=p b a, respectively, where q=p
con-tains the weak phase of B0-B0 oscillations. The C and S
coefficients are given by the same expressions, replacing
bwith b, with , and with .
In the B ! J= K0 selection, a J= candidate must consist of two identified lepton tracks [5] that form a good vertex. The lepton-pair invariant mass must be in the range 3:06–3:14 GeV=c2 for muons and
2:95–3:14 GeV=c2 for electrons. This corresponds to a
3# interval for muons, and, for electrons, accommo-dates the remaining radiative tail after bremsstrahlung correction [6]. We form K candidate pairs, where the track that is most consistent with being a kaon is assigned to be the kaon candidate. The K pair must have an invariant mass within 100 MeV=c2 of the nominal
K0892 mass [9]. In the selected mass window the
K01430 contributes 7:3 1:6% of the K events.
The B-meson candidates are formed from J= and
K candidates with the requirement that the differ-ence E Ecm
B Ecmbeam between their energy and the
beam energy in the center-of-mass frame be less than 30 MeV from zero. The beam-energy-substituted mass
mES Ecm beam2 pcmB 2
q
must be greater than 5:2 GeV=c2, where pcm
B is the measured B momentum in
the center-of-mass frame. We define a signal region with
mES> 5:27 GeV=c2 to determine event yields and
puri-ties, and a sideband region with mES< 5:27 GeV=c2 to
study background properties. If several B candidates are found in an event, the one with the smallest jEj is retained.
A measurement of the asymmetry coefficients C, S, C, and S requires a determination of the experimental t resolution and the fraction w of events in which the flavor tag assignment is incorrect. This mistag fraction reduces the amplitudes of the observed asymmetries by a factor 1 2w. Mistag fractions and t resolution functions are determined from a sample of neutral B mesons that decay to final states with one charmed meson (BDh) and consists of the channels Dh (h , ( , and a
1).
The algorithm for B-flavor tagging is explained in Ref. [10]. The total efficiency for assigning a recon-structed B candidate to one of four hierarchical, mutually exclusive tagging categories is 65:6 0:5%. Untagged events are excluded from further consideration. The
ef-fective tagging efficiency Q Pi"i1 2wi2, where "i
and wi are the efficiencies and mistag probabilities, for events tagged in category i, is measured to be 28:1 0:7%.
The time interval t between the two B decays is calculated from the measured separation z between the decay vertices of the Brec and Btagalong the collision (z) axis [6]. We determine the z position of the Brecvertex from its charged tracks. The Btagvertex is determined by fitting tracks not belonging to the Brec candidate to a
common vertex, employing constraints from the beam spot location and the Brecmomentum [6]. We accept events
with a t uncertainty of less than 2.5 ps and jtj < 20 ps. The fraction of events satisfying these requirements is 95%.
Figure 1 shows the mESdistributions of the J= K
and J= K candidates that satisfy the tagging and vertexing requirements. The mESdistributions are fit with the sum of a threshold function [11], which accounts for the background from random combinations of tracks in the event, and a Gaussian distribution describing the signal. In Table I we list the event yields and signal purities for the tagged B ! J= K and B !
J= K candidates. The fraction of events in the Gaussian component of the mESfits due to other B decay
modes is estimated to be 1:6 0:4% based on simulated events. B → J/ψ K+π -background Events / 2.5 MeV/c 2 B → J/ψ K-π+ background mES (GeV/c2) 0 100 200 300 0 100 200 300 5.2 5.22 5.24 5.26 5.28 5.3 (a) (b)
FIG. 1. Distributions of mES(a) for J= K candidates and
(b) for J= K candidates satisfying the tagging and vertex-ing requirements. The fit is described in the text.
TABLE I. Number of events, Ntag, and signal purity, P, in the
signal region for the J= K and J= K samples and for the BDh sample. Errors are statistical only.
Sample Ntag P%
J= K sample 860 95:5 0:7 J= K sample 856 96:5 0:6
We determine the C, S, C, and S coefficients with a simultaneous unbinned maximum likelihood fit to the t distributions of the tagged BJ= K and BDh samples. In
this fit the t distributions of the J= K and
J= K samples are described by Eq. (1). The t distributions of the BDh sample are described by the same equation with C 1 and S 0. The observed amplitudes for the time-dependent asymmetries in the
BJ= Ksample and for flavor oscillation in the BDh
sam-ple are reduced by the same factor, 1 2w, due to flavor mistags. Events are assigned signal and background prob-abilities based on the mES distributions. The t distribu-tions for the signal are convolved with a common resolution function, modeled by the sum of three Gaussians [6]. Backgrounds are incorporated by means of an empirical description of their t spectra, obtained from the mES-sideband region, containing prompt and nonprompt components convolved with a resolution func-tion [6] distinct from that of the signal.
There are 48 free parameters in the fit. The fit parame-ters that describe the signal t distributions are C, S, C, and S (4), the average mistag fraction w, the difference w between B0 and B0 mistag fractions, and the linear
dependence of the mistag fraction on the t error for each tagging category (12), parameters for the signal t reso-lution (8), and parameters to account for differences in reconstruction and tagging efficiencies for B0 and B0
mesons (5). The BJ= Kand BDhbackground t
distribu-tions are described by parameters for the background time dependence (8), t resolution (3), and mistag frac-tions (8). We fix B0at 1.542 ps and mdat 0:489 ps1[9]. The determination of the mistag fractions and t resolu-tion funcresolu-tion parameters for the signal is dominated by the large BDhsample. Background parameters are
deter-mined from events with mES< 5:27 GeV=c2.
The fit to the BJ= K and BDh samples yields C
1:045 0:058 0:035, S 0:024 0:095 0:041, C 0:966 0:051 0:035, and S 0:004 0:090
0:041, where the first error is statistical and the second error is systematic. Figure 2 shows the t distributions and the asymmetries in yields between B0 tags and B0 tags as a function of t for the J= K and J= K
samples, overlaid with the projection of the likelihood fit result.
We estimate common systematic errors for C (S) and C (S). The dominant sources of systematic error are the uncertainties in the level, composition, and time-dependent asymmetry of the background in the selected
BJ= Ksample (0.016 for C, 0.017 for S), uncertainties in the beam spot location and the internal alignment of the vertex detector (0.016 for C, 0.021 for S), and the statistics of the simulated event sample (0.016 for C, 0.015 for S). Another significant contribution to the systematic uncer-tainty in the cosine coefficients comes from possible differences between the BDhand BJ= Kmistag fractions
(0.012). The uncertainty in the interference between the suppressed b !uc damplitude with the favored b ! c ud
amplitude for the decay modes in the BDhsample and for certain tagside B decays to hadronic final states [12] contributes to the systematic uncertainty in the sine co-efficients (0.019). Finally, there are differences in the angular-integrated efficiency for the B ! J= K0892 helicity amplitudes and the B ! J= K01430 amplitude (0.007 for C, 0.016 for S). The total systematic errors for the cosine coefficients and sine coefficients are 0.035 and 0.041, respectively. Most systematic errors are deter-mined with data and are expected to decrease with larger sample size.
The large J= K and J= K samples allow a number of consistency checks, including separation by data-taking period and tagging category. The results of fits to these subsamples are found to be statistically consistent.
The measured values of the cosine and sine coefficients are consistent with C C 1 and S S 0, as ex-pected for no contributions from the wrong-flavor decays
B0! J= K and B0 ! J= K . We use the
mea-sured cosine coefficients C and C and assume jq=pj 1 [13] to calculate the wrong-flavor to favored decay rate ratios "B0! J= K
="B0 ! J= K
jb=aj2 0:022 0:028 stat: 0:016 syst: and
"B0 ! J= K
="B0 ! J= K
j b=aj2 0:017 0:026stat: 0:016syst:, where the negative
Entries / 0.6 ps J/ψ K+π -J/ψ K-π+ a) opposite-flavor tag b) same-flavor tag Asymmetry ∆t (ps) c) asymmetry 0 50 100 0 10 20 30 -0.5 0 0.5 -10 -5 0 5 10
FIG. 2. Number of J= K and J= K candidates in the signal region (a) with an opposite-flavor B tag, NOF,
(b) with a same-flavor B tag, NSF, and (c) the observed
asymmetry NOF NSF=NOF NSF as functions of t. In
each figure the solid (dashed) curve represents the fit projection in t for J= K J= K candidates. The shaded
regions in (a) and (b) represent the background contributions.
central value occurs because C > 1. From these measure-ments the wrong-flavor to favored amplitude ratios for
B ! J= K0892 and B ! J= K0892 can be
calcu-lated. Using the measured fraction of B ! J= K01430 events contributing in the B ! J= K selection, the upper limits for the decay amplitude ratios at 90% con-fidence level (C.L.) are found to be jAB0 !
J= K0j=jAB0! J= K0j < 0:26 and jAB0 !
J= K0j=jAB0! J= K0j < 0:32. For the single ratio
of wrong-flavor to favored amplitude for B0and B0 com-bined, we determine an upper limit of 0.25 at 90% C.L.
In conclusion, we observe no evidence for the wrong-flavor decays B0 ! J= K0892 and B0! J= K0892.
Together with theoretical information on the relation between the matrix elements for B0! J= K0 and B0 !
J= K0[3], the results presented here can be used to set a limit on the difference between ACPJ= K0
S and
ACPJ= K0
L.
We are grateful for the excellent luminosity and ma-chine conditions provided by our PEP-II colleagues and for the substantial dedicated effort from the computing organizations that support BABAR. The collaborating in-stitutions wish to thank SLAC for its support and kind hospitality. This work is supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF and DFG (Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the A. P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation.
*Now at Department of Physics, University of Warwick, Coventry, United Kingdom.
†Also at Universita` della Basilicata, Potenza, Italy. ‡Also at IFIC, Instituto de Fı´sica Corpuscular,
CSIC-Universidad de Valencia, Valencia, Spain.
x
Deceased.
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