B-meson decays to eta#rho, eta#f0, and eta#K*
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Citation
del Amo Sanchez, P. et al. “B-meson decays to eta^{'} rho ,
eta^{'}f_{0}, and eta^{'}K^{*}.” Physical Review D 82.1 (2010):
011502.© 2010 The American Physical Society.
As Published
http://dx.doi.org/10.1103/PhysRevD.82.011502
Publisher
American Physical Society
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Final published version
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http://hdl.handle.net/1721.1/60976
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B-meson decays to
0,
0f
0
, and
0K
P. del Amo Sanchez,1J. P. Lees,1V. Poireau,1E. Prencipe,1V. Tisserand,1J. Garra Tico,2E. Grauges,2M. Martinelli,3a,3b A. Palano,3a,3bM. Pappagallo,3a,3bG. Eigen,4B. Stugu,4L. Sun,4M. Battaglia,5D. N. Brown,5B. Hooberman,5 L. T. Kerth,5Yu. G. Kolomensky,5G. Lynch,5I. L. Osipenkov,5T. Tanabe,5C. M. Hawkes,6A. T. Watson,6H. Koch,7 T. Schroeder,7D. J. Asgeirsson,8C. Hearty,8T. S. Mattison,8J. A. McKenna,8A. Khan,9A. Randle-Conde,9V. E. Blinov,10
A. R. Buzykaev,10V. P. Druzhinin,10V. B. Golubev,10A. P. Onuchin,10S. I. Serednyakov,10Yu. I. Skovpen,10 E. P. Solodov,10K. Yu. Todyshev,10A. N. Yushkov,10M. Bondioli,11S. Curry,11D. Kirkby,11A. J. Lankford,11 M. Mandelkern,11E. C. Martin,11D. P. Stoker,11H. Atmacan,12J. W. Gary,12F. Liu,12O. Long,12G. M. Vitug,12 C. Campagnari,13T. M. Hong,13D. Kovalskyi,13J. D. Richman,13A. M. Eisner,14C. A. Heusch,14J. Kroseberg,14
W. S. Lockman,14A. J. Martinez,14T. Schalk,14B. A. Schumm,14A. Seiden,14L. O. Winstrom,14C. H. Cheng,15 D. A. Doll,15B. Echenard,15D. G. Hitlin,15P. Ongmongkolkul,15F. C. Porter,15A. Y. Rakitin,15R. Andreassen,16 M. S. Dubrovin,16G. Mancinelli,16B. T. Meadows,16M. D. Sokoloff,16P. C. Bloom,17W. T. Ford,17A. Gaz,17 J. F. Hirschauer,17M. Nagel,17U. Nauenberg,17A. Penzkofer,17J. G. Smith,17S. R. Wagner,17R. Ayad,18,*W. H. Toki,18
T. M. Karbach,19J. Merkel,19A. Petzold,19B. Spaan,19K. Wacker,19M. J. Kobel,20K. R. Schubert,20R. Schwierz,20 D. Bernard,21M. Verderi,21P. J. Clark,22S. Playfer,22J. E. Watson,22M. Andreotti,23a,23bD. Bettoni,23aC. Bozzi,23a
R. Calabrese,23a,23bA. Cecchi,23a,23bG. Cibinetto,23a,23bE. Fioravanti,23a,23bP. Franchini,23a,23bE. Luppi,23a,23b M. Munerato,23a,23bM. Negrini,23a,23bA. Petrella,23a,23bL. Piemontese,23aR. Baldini-Ferroli,24A. Calcaterra,24 R. de Sangro,24G. Finocchiaro,24M. Nicolaci,24S. Pacetti,24P. Patteri,24I. M. Peruzzi,24,†M. Piccolo,24M. Rama,24 A. Zallo,24R. Contri,25a,25bE. Guido,25a,25bM. Lo Vetere,25a,25bM. R. Monge,25a,25bS. Passaggio,25aC. Patrignani,25a,25b
E. Robutti,25aS. Tosi,25a,25bB. Bhuyan,26C. L. Lee,27M. Morii,27A. Adametz,28J. Marks,28S. Schenk,28U. Uwer,28 F. U. Bernlochner,29H. M. Lacker,29T. Lueck,29A. Volk,29P. D. Dauncey,30M. Tibbetts,30P. K. Behera,31U. Mallik,31
C. Chen,32J. Cochran,32H. B. Crawley,32L. Dong,32W. T. Meyer,32S. Prell,32E. I. Rosenberg,32A. E. Rubin,32 Y. Y. Gao,33A. V. Gritsan,33Z. J. Guo,33N. Arnaud,34M. Davier,34D. Derkach,34J. Firmino da Costa,34G. Grosdidier,34
F. Le Diberder,34A. M. Lutz,34B. Malaescu,34A. Perez,34P. Roudeau,34M. H. Schune,34J. Serrano,34V. Sordini,34,‡ A. Stocchi,34L. Wang,34G. Wormser,34D. J. Lange,35D. M. Wright,35I. Bingham,36J. P. Burke,36C. A. Chavez,36 J. P. Coleman,36J. R. Fry,36E. Gabathuler,36R. Gamet,36D. E. Hutchcroft,36D. J. Payne,36C. Touramanis,36A. J. Bevan,37 F. Di Lodovico,37R. Sacco,37M. Sigamani,37G. Cowan,38S. Paramesvaran,38A. C. Wren,38D. N. Brown,39C. L. Davis,39
A. G. Denig,40M. Fritsch,40W. Gradl,40A. Hafner,40K. E. Alwyn,41D. Bailey,41R. J. Barlow,41G. Jackson,41 G. D. Lafferty,41T. J. West,41J. Anderson,42R. Cenci,42A. Jawahery,42D. A. Roberts,42G. Simi,42J. M. Tuggle,42 C. Dallapiccola,43E. Salvati,43R. Cowan,44D. Dujmic,44P. H. Fisher,44G. Sciolla,44M. Zhao,44D. Lindemann,45 P. M. Patel,45S. H. Robertson,45M. Schram,45P. Biassoni,46a,46bA. Lazzaro,46a,46bV. Lombardo,46aF. Palombo,46a,46b S. Stracka,46a,46bF. C. Ungaro,46aL. Cremaldi,47R. Godang,47,xR. Kroeger,47P. Sonnek,47D. J. Summers,47H. W. Zhao,47
X. Nguyen,48M. Simard,48P. Taras,48G. De Nardo,49a,49bD. Monorchio,49a,49bG. Onorato,49a,49bC. Sciacca,49a,49b G. Raven,50H. L. Snoek,50C. P. Jessop,51K. J. Knoepfel,51J. M. LoSecco,51W. F. Wang,51L. A. Corwin,52 K. Honscheid,52R. Kass,52J. P. Morris,52A. M. Rahimi,52N. L. Blount,53J. Brau,53R. Frey,53O. Igonkina,53J. A. Kolb,53 R. Rahmat,53N. B. Sinev,53D. Strom,53J. Strube,53E. Torrence,53G. Castelli,54a,54bE. Feltresi,54a,54bN. Gagliardi,54a,54b M. Margoni,54a,54bM. Morandin,54aM. Posocco,54aM. Rotondo,54aF. Simonetto,54a,54bR. Stroili,54a,54bE. Ben-Haim,55 G. R. Bonneaud,55H. Briand,55G. Calderini,55J. Chauveau,55O. Hamon,55Ph. Leruste,55G. Marchiori,55J. Ocariz,55
J. Prendki,55S. Sitt,55M. Biasini,56a,56bE. Manoni,56a,56bC. Angelini,57a,57bG. Batignani,57a,57bS. Bettarini,57a,57b M. Carpinelli,57a,57b,kG. Casarosa,57a,57bA. Cervelli,57a,57bF. Forti,57a,57bM. A. Giorgi,57a,57bA. Lusiani,57cN. Neri,57a,57b
E. Paoloni,57a,57bG. Rizzo,57a,57bJ. J. Walsh,57aD. Lopes Pegna,58C. Lu,58J. Olsen,58A. J. S. Smith,58A. V. Telnov,58 F. Anulli,59aE. Baracchini,59a,59bG. Cavoto,59aR. Faccini,59a,59bF. Ferrarotto,59aF. Ferroni,59a,59bM. Gaspero,59a,59b L. Li Gioi,59aM. A. Mazzoni,59aG. Piredda,59aF. Renga,59a,59bM. Ebert,60T. Hartmann,60T. Leddig,60H. Schro¨der,60 R. Waldi,60T. Adye,61B. Franek,61E. O. Olaiya,61F. F. Wilson,61S. Emery,62G. Hamel de Monchenault,62G. Vasseur,62
Ch. Ye`che,62M. Zito,62M. T. Allen,63D. Aston,63D. J. Bard,63R. Bartoldus,63J. F. Benitez,63C. Cartaro,63 M. R. Convery,63J. Dorfan,63G. P. Dubois-Felsmann,63W. Dunwoodie,63R. C. Field,63M. Franco Sevilla,63 B. G. Fulsom,63A. M. Gabareen,63M. T. Graham,63P. Grenier,63C. Hast,63W. R. Innes,63M. H. Kelsey,63H. Kim,63
P. Kim,63M. L. Kocian,63D. W. G. S. Leith,63S. Li,63B. Lindquist,63S. Luitz,63V. Luth,63H. L. Lynch,63 D. B. MacFarlane,63H. Marsiske,63D. R. Muller,63H. Neal,63S. Nelson,63C. P. O’Grady,63I. Ofte,63M. Perl,63 T. Pulliam,63B. N. Ratcliff,63A. Roodman,63A. A. Salnikov,63V. Santoro,63R. H. Schindler,63J. Schwiening,63
A. Snyder,63D. Su,63M. K. Sullivan,63S. Sun,63K. Suzuki,63J. M. Thompson,63J. Va’vra,63A. P. Wagner,63M. Weaver,63 C. A. West,63W. J. Wisniewski,63M. Wittgen,63D. H. Wright,63H. W. Wulsin,63A. K. Yarritu,63C. C. Young,63 V. Ziegler,63X. R. Chen,64W. Park,64M. V. Purohit,64R. M. White,64J. R. Wilson,64S. J. Sekula,65M. Bellis,66 P. R. Burchat,66A. J. Edwards,66T. S. Miyashita,66S. Ahmed,67M. S. Alam,67J. A. Ernst,67B. Pan,67M. A. Saeed,67
S. B. Zain,67N. Guttman,68A. Soffer,68P. Lund,69S. M. Spanier,69R. Eckmann,70J. L. Ritchie,70A. M. Ruland,70 C. J. Schilling,70R. F. Schwitters,70B. C. Wray,70J. M. Izen,71X. C. Lou,71F. Bianchi,72a,72bD. Gamba,72a,72b M. Pelliccioni,72a,72bM. Bomben,73a,73bL. Lanceri,73a,73bL. Vitale,73a,73bN. Lopez-March,74F. Martinez-Vidal,74
D. A. Milanes,74A. Oyanguren,74J. Albert,75Sw. Banerjee,75H. H. F. Choi,75K. Hamano,75G. J. King,75 R. Kowalewski,75M. J. Lewczuk,75I. M. Nugent,75J. M. Roney,75R. J. Sobie,75T. J. Gershon,76P. F. Harrison,76J. Ilic,76
T. E. Latham,76E. M. T. Puccio,76H. R. Band,77X. Chen,77S. Dasu,77K. T. Flood,77Y. Pan,77R. Prepost,77 C. O. Vuosalo,77and S. L. Wu77
1Laboratoire d’Annecy-le-Vieux de Physique des Particules (LAPP), Universite´ de Savoie,
CNRS/IN2P3, F-74941 Annecy-Le-Vieux, France
2
Universitat de Barcelona, Facultat de Fisica, Departament ECM, E-08028 Barcelona, Spain
3aINFN Sezione di Bari, I-70126 Bari, Italy
3bDipartimento di Fisica, Universita` di Bari, I-70126 Bari, Italy 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 British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
9Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom 10
Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia
11University of California at Irvine, Irvine, California 92697, USA 12University of California at Riverside, Riverside, California 92521, USA 13University of California at Santa Barbara, Santa Barbara, California 93106, USA
14University of California at Santa Cruz, Institute for Particle Physics, Santa Cruz, California 95064, USA 15California Institute of Technology, Pasadena, California 91125, USA
16University of Cincinnati, Cincinnati, Ohio 45221, USA 17University of Colorado, Boulder, Colorado 80309, USA 18Colorado State University, Fort Collins, Colorado 80523, USA
19Technische Universita¨t Dortmund, Fakulta¨t Physik, D-44221 Dortmund, Germany
20Technische Universita¨t Dresden, Institut fu¨r Kern- und Teilchenphysik, D-01062 Dresden, Germany 21Laboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole Polytechnique, F-91128 Palaiseau, France
22University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom 23aINFN Sezione di Ferrara, I-44100 Ferrara, Italy
23bDipartimento di Fisica, Universita` di Ferrara, I-44100 Ferrara, Italy 24INFN Laboratori Nazionali di Frascati, I-00044 Frascati, Italy
25a
INFN Sezione di Genova, I-16146 Genova, Italy
25bDipartimento di Fisica, Universita` di Genova, I-16146 Genova, Italy 26Indian Institute of Technology Guwahati, Guwahati, Assam, 781 039, India
27Harvard University, Cambridge, Massachusetts 02138, USA
28Universita¨t Heidelberg, Physikalisches Institut, Philosophenweg 12, D-69120 Heidelberg, Germany 29Humboldt-Universita¨t zu Berlin, Institut fu¨r Physik, Newtonstr. 15, D-12489 Berlin, Germany
30Imperial College London, London, SW7 2AZ, United Kingdom 31University of Iowa, Iowa City, Iowa 52242, USA 32Iowa State University, Ames, Iowa 50011-3160, USA 33Johns Hopkins University, Baltimore, Maryland 21218, USA
34Laboratoire de l’Acce´le´rateur Line´aire, IN2P3/CNRS et Universite´ Paris-Sud 11,
Centre Scientifique d’Orsay, B. P. 34, F-91898 Orsay Cedex, France
35Lawrence Livermore National Laboratory, Livermore, California 94550, USA 36University of Liverpool, Liverpool L69 7ZE, United Kingdom 37Queen Mary, University of London, 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
40Johannes Gutenberg-Universita¨t Mainz, Institut fu¨r Kernphysik, D-55099 Mainz, Germany 41University of Manchester, Manchester M13 9PL, United Kingdom
42University of Maryland, College Park, Maryland 20742, USA
P. DEL AMO SANCHEZ et al. PHYSICAL REVIEW D 82, 011502(R) (2010)
43University of Massachusetts, Amherst, Massachusetts 01003, USA
44Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge, Massachusetts 02139, USA 45McGill University, Montre´al, Que´bec, Canada H3A 2T8
46aINFN Sezione di Milano, I-20133 Milano, Italy
46bDipartimento di Fisica, Universita` di Milano, I-20133 Milano, Italy 47University of Mississippi, University, Mississippi 38677, USA
48Universite´ de Montre´al, Physique des Particules, Montre´al, Que´bec, Canada H3C 3J7 49aINFN Sezione di Napoli, I-80126 Napoli, Italy
49b
Dipartimento di Scienze Fisiche, Universita` di Napoli Federico II, 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
52Ohio State University, Columbus, Ohio 43210, USA 53University of Oregon, Eugene, Oregon 97403, USA 54aINFN Sezione di Padova, I-35131 Padova, Italy
54bDipartimento di Fisica, Universita` di Padova, I-35131 Padova, Italy
55Laboratoire de Physique Nucle´aire et de Hautes Energies, IN2P3/CNRS, Universite´ Pierre et Marie Curie-Paris6,
Universite´ Denis Diderot-Paris7, F-75252 Paris, France
56aINFN Sezione di Perugia, I-06100 Perugia, Italy
56bDipartimento di Fisica, Universita` di Perugia, I-06100 Perugia, Italy 57aINFN Sezione di Pisa, I-56127 Pisa, Italy
57bDipartimento di Fisica, Universita` di Pisa, I-56127 Pisa, Italy 57cScuola Normale Superiore di Pisa, I-56127 Pisa, Italy 58Princeton University, Princeton, New Jersey 08544, USA
59aINFN Sezione di Roma, I-00185 Roma, Italy 59b
Dipartimento di Fisica, Universita` di Roma La Sapienza, I-00185 Roma, Italy
60Universita¨t Rostock, D-18051 Rostock, Germany
61Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, United Kingdom 62CEA, Irfu, SPP, Centre de Saclay, F-91191 Gif-sur-Yvette, France
63SLAC National Accelerator Laboratory, Stanford, California 94309 USA 64University of South Carolina, Columbia, South Carolina 29208, USA
65Southern Methodist University, Dallas, Texas 75275, USA 66Stanford University, Stanford, California 94305-4060, USA 67State University of New York, Albany, New York 12222, USA 68Tel Aviv University, School of Physics and Astronomy, Tel Aviv, 69978, Israel
69University of Tennessee, Knoxville, Tennessee 37996, USA 70University of Texas at Austin, Austin, Texas 78712, USA 71University of Texas at Dallas, Richardson, Texas 75083, USA
72aINFN Sezione di Torino, I-10125 Torino, Italy
72bDipartimento di Fisica Sperimentale, Universita` di Torino, I-10125 Torino, Italy 73aINFN Sezione di Trieste, I-34127 Trieste, Italy
73bDipartimento di Fisica, Universita` di Trieste, I-34127 Trieste, Italy 74IFIC, Universitat de Valencia-CSIC, E-46071 Valencia, Spain 75University of Victoria, Victoria, British Columbia, Canada V8W 3P6 76Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
77University of Wisconsin, Madison, Wisconsin 53706, USA
(Received 5 April 2010; published 29 July 2010)
We present measurements of B-meson decays to the final states 0, 0f0, and 0K, where Kstands
for a vector, scalar, or tensor strange meson. We observe a significant signal or evidence for 0þand all the 0Kchannels. We also measure, where applicable, the charge asymmetries, finding results consistent with no direct CP violation in all cases. The measurements are performed on a data sample consisting of 467 106B B pairs, collected with the BABAR detector at the PEP-II eþecollider at the SLAC National
Accelerator Laboratory. Our results favor the theoretical predictions from perturbative QCD and QCD
†Also at Universita` di Perugia, Dipartimento di Fisica, Perugia, Italy.
kAlso at Universita` di Sassari, Sassari, Italy.
xPresent address: University of South Alabama, Mobile, AL 36688, USA. ‡Also at Universita` di Roma La Sapienza, I-00185 Roma, Italy.
*Present address: Temple University, Philadelphia, PA 19122, USA.
factorization and we observe an enhancement of the tensor K2ð1430Þ with respect to the vector Kð892Þ component.
DOI:10.1103/PhysRevD.82.011502 PACS numbers: 13.25.Hw, 12.15.Hh, 11.30.Er
Charmless two-body decays of B mesons are a powerful probe for testing the standard model and searching for new physics phenomena [1]. Decays to final states containing or 0 mesons exhibit a distinctive pattern of interference among the dominant amplitudes and are also sensitive to a potentially large flavor-singlet contribution [2]. B meson decays to the final states 0 and 0Kð892Þ have been investigated theoretically within the standard model by
means of perturbative QCD (pQCD) [3], QCD
factoriza-tion (QCDF) [4], soft collinear effective theory (SCET) [5], and SUð3Þ flavor symmetry [6]. The predicted branching fractions to the final states 0Kð892Þþand 0Kð892Þ0are in the range of a few times106, whereas the branching fraction for B0! 00is suppressed to107108. There is some disagreement on the predictions of the branching fraction for Bþ! 0þ: SCET calculations give a value of0:4 106, whereas pQCD and QCDF predict a branch-ing fraction of ð6–9Þ 106. There are no theoretical predictions for the branching fraction of B0 ! 0f0.
Experimentally, searches for these decays have been performed by the BABAR [7] and Belle [8] collaborations. The former claimed evidence for the 0þ, 0Kð892Þþ, and 0Kð892Þ0 final states, while the latter establishes upper limits that are in poor agreement with the branching fractions, in the rangeð4–9Þ 106, measured by BABAR. Very few predictions exist for B-meson decays to 0K0ð1430Þ and 0K2ð1430Þ. In Ref. [9], based on pQCD, the branching fraction of B ! 0K0ð1430Þ is pre-dicted to be in the rangeð20–80Þ 106, while in Ref. [10] the branching fraction of B ! 0K2ð1430Þ is calculated to be2 106, exploiting QCDF calculations. No searches for the 0K0ð1430Þ and 0K2ð1430Þ final states have been reported. In a recent study of B ! !Kdecays [11], where Kdenotes the spin 0, 1, or 2 states K0ð1430Þ, Kð892Þ, and K2ð1430Þ, the tensor and scalar Kcomponents were found to be significantly larger than the vector Kð892Þ, a fact which was not anticipated by theory.
In this paper, we report measurements of the branching fractions of B mesons decaying to the final states 0, 0f0, and 0K. Where applicable, we also measure the charge asymmetryAch ð þÞ=ðþ þÞ, where the superscript to the decay width refers to the charge of the Bmeson or to the charge of the kaon in the neutral B decays.
For this analysis, we use the full BABAR dataset, col-lected at the PEP-II asymmetric-energy eþe collider located at the SLAC National Accelerator Laboratory, consisting of 467 106 B B pairs originating from the decay of the ð4SÞ resonance, produced at a
center-of-mass energy pffiffiffis¼ 10:58 GeV. The BABAR detector is
described in detail elsewhere [12].
We reconstruct B-daughter candidates through their de-cays 0 ! þ (0 ), 0! 0 (0), ! , þ! þ0, 0 ! þ, f0ð980Þ ! þ [13], K0! Kþ, Kþ! Kþ0 (KþKþ0), Kþ! KS0þ (KþK0 Sþ), K 0
S! þ, and 0 ! . We use both 0! þ and 0! 0 for 0K, but due to the larger backgrounds affecting the 0channel, we do not use the 0 ! 0 decay mode for the 0 and 0f0 final states. We require the invariant masses of the B-daughter
candi-dates to satisfy the following requirements: 910 <
mð0Þ < 1000 MeV, 510 < mðÞ < 580 MeV, 510 < mð=f0Þ < 1060 MeV, 750 < mðKÞ < 1550 MeV, 488 < mðK0
SÞ < 508 MeV, and 120<mð0Þ<150 MeV; these mass intervals are chosen to include sidebands to estimate the background levels. We require the photon energy of the 0 candidates to be greater than 30 MeV in the laboratory frame, while the minimum energy is 100 MeV for the photons of candidates and 200 MeV for the photons from the 0! 0 decay. A fit constrain-ing the two pion tracks from the K0Sdecay to originate from the same decay vertex is performed and a KS0 candidate is selected if its flight length exceeds 3 times its uncertainty. Daughter particles from 0, , , f0, and K decays are rejected if their particle identification signatures are con-sistent with those of electrons or protons; Kþ candidates are required to be positively identified as kaons, and pions must fail this criterion. Unless otherwise stated, charge-conjugate reactions are always implied.
A B-meson candidate is characterized by two kinematic variables, whose small correlation is accounted for in the correction of the fit bias: the energy substituted mass
mES
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi s=4 p2B q
and the energy differenceE EB
ffiffiffi s p
=2, where ðEB; pBÞ is the B-meson four-momentum
vector in the ð4SÞ rest frame. Signal events peak at 0 in E and at the B mass [14] in mES, with a resolution inE
(mES) of 20–35 MeV (3 MeV). We select events with
5:25 < mES< 5:29 GeV and jEj < 0:2 GeV.
The dominant backgrounds arise from random combi-nations of particles in continuum eþe! q q events (q ¼ u, d, s, c). The angle Tbetween the thrust axis [15] of the B candidate in the ð4SÞ rest frame and that of the remain-ing particles in the event is used to suppress this back-ground. Jet-like continuum events peak atj cosTj close to 1, while spherical B decays exhibit a flat distribution for this variable. Further rejection is achieved by restricting the range of the helicity angle of the or K meson. The helicity angle H is defined in the rest frame of the or K and corresponds to the angle between two vectors: one is the momentum of the daughter pion and the other is the
P. DEL AMO SANCHEZ et al. PHYSICAL REVIEW D 82, 011502(R) (2010)
direction of the boost into this rest frame from the B meson rest frame; for the þ candidate, we use the positively
charged pion. Table I summarizes the requirements we
apply onj cosTj and cosH. After the selection criteria have been applied, the average number of combinations per event in data is between 1.1 and 1.3, and we select the candidate with the highest 2probability in a geometric fit to a common B-decay vertex. In this way the probability of selecting the correctly reconstructed event is a few percent higher with respect to a random selection.
Further signal/background separation is provided by a Fisher discriminantF exploiting four variables sensitive to the production dynamics and event shape: the polar angles, with respect to the beam axis in the eþecenter-of-mass frame, of the B candidate momentum and of the B thrust axis; and the zeroth and second angular moments L0;2 of the energy flow, excluding the B candidate. The moments
are defined by Lj¼
P
ipi j cosijj, where i labels a track or neutral cluster, i is its angle with respect to the B thrust axis, and piis its momentum. The mean ofF is shifted so that it is independent of the B-flavor tagging category [16] for q q background. The Fisher variable provides about 1 standard deviation discrimination be-tween B-decay events and continuum background.
We obtain the yields and the charge asymmetriesAch from extended maximum-likelihood fits to the six
observ-ables: E, mES, F , the masses of the two resonance
candidates m0 and m=f0=K, and cosH. The fits distin-guish among several categories: q q background, B B back-ground, and signal component(s) (one for 0þ, two for 00=f0, and three for the 0K modes). For each event i and category j, we define the probability density functions (PDFs) PjðxÞ for the variable x, with the resulting
like-lihoodL: Pi j¼ PjðmiESÞPjðEiÞPjðFiÞ (1) Pjðmi0ÞPjðm=fi 0=KÞPjðcosiHÞ; L ¼e P j Yj N! YN i¼1 X j YjPij; (2)
where Yjis the yield for category j, and N is the number of events entering the fit. Where applicable, we split the yields by the flavor of the decaying B meson in order to measureAch. We find correlations among the observables to be significant in the B B components, whereas those are small in the data samples, which contain mostly q q back-ground. An exception occurs in the Bþ! 0KKþþ0
mode, for which the correlation between mK and
cosH, if not taken into account, may cause large biases in the yield of the different Kcomponents. In this case the factors for miK andcosiH in Eq. (1) are replaced with a
two-dimensional nonparametric PDF [17]. We discuss be-low our treatment of the somewhat larger correlations found in simulated signal events.
The signal component is studied from the Monte Carlo (MC) simulation [18] of the decay process and the re-sponse of the detector and reconstruction chain. Signal events selected in simulation contain both properly recon-structed and incorrectly reconrecon-structed B-meson candi-dates, which are labeled as ‘‘self-crossfeed’’ (SXF). SXF occurs either when some particles from the correct parent B meson are incorrectly assigned to intermediate reso-nances or when particles from the rest of the event are used in the signal B reconstruction. The fraction of SXF events ranges between 14% and 32% and we do not separate correctly reconstructed events from SXF in the fit. For the scalar K component, we use the LASS model [19,20], which consists of the K0ð1430Þ resonance together
with an effective-range nonresonant component.
Backgrounds arising from B B decays to charmless final states are modeled from the simulation. We select the channels (20–40 for each final state) which have a high probability of passing our selection and build a sample of simulated specimens of these, weighting each component by its branching fraction, either measured or estimated. We model from this sample the PDFs for the B B background component and fix its yield (25–350 events, depending on the final state) to the MC prediction. Backgrounds arising from b ! c transitions have distributions very similar to those of q q events and thus they are absorbed by the
continuum component. For the 0 modes, we estimate
the contribution of the nonresonant 0 with a fit of the data, selecting only the central region (which excludes the region across the and f0resonances) of the 0 Dalitz plot. The expected nonresonant component is then in-cluded in the charmless B B background PDF. This
proce-dure is not necessary for the 0K fits, since the
nonresonant 0K component is already included in the LASS model.
PDF shapes for the signals and B B background are
determined from fits to MC samples, while for the q q component we use data sidebands, which we obtain ex-cluding the signal region 5:27 < mES< 5:29 GeV and
jEj < 0:075 GeV. The calibration of mES and E is
checked by means of large data control samples of B
TABLE I. Selection requirements oncosTandcosH for the different modes.
State j cosTj cosH range
00=f0 <0:9 [ 0:95, 0.95] 0þ <0:9 [ 0:80, 1] 0K0 <0:9 [ 0:85, 1] 0K0 <0:6 [ 0:85, 1] 0KþKþ0 <0:9 [ 0:75, 1] 0KKþþ0 <0:7 [ 0:75, 1] 0KþKþ0 <0:9 [ 0:90, 1] 0KKþþ0 <0:7 [ 0:90, 1]
decays to charmed mesons with topology similar to the decays under study [e.g. Bþ! D0ðKþ0Þþ, Bþ !
D0ðKþ0Þþ].
We use a combination of Gaussian, exponential, and polynomial functions to parametrize most of the PDFs. For the mESdistribution of the q q background component, we use a parametrization motivated by phase-space argu-ments [21]. The following are free to vary in the fit: the signal and q q background yields and charge asymmetries Ach, along with the parameters that most strongly influ-ence the shape of the continuum background.
We perform fits to ensembles of simulated experiments in order to evaluate the potential bias Y0on the fitted signal yield, which originates from our neglect of the correlations among the variables. Each such experiment has the same number of signal and background candidates as the data; given that correlations among fit variables are negligible for q q events, these are generated from the PDFs, while signal and B B background events are taken from fully simulated MC samples. In computing the branching
frac-tionB for each mode, we subtract Y0from the fitted signal yield Y and divide by the selection efficiency " for signal events, the number of B mesons in our sample, and the product of the branching fractions of the intermediate resonances, QBi. We assume the branching fraction of ð4SÞ to BþBand B0 B0to be the same and equal to 50%, consistent with the measurements [14]. The efficiency " is evaluated from the simulation.
The different submodes of 0K0 and 0Kþ are com-bined by adding their2 lnL curves. For the significance of observation S, we take the difference between the value of2 lnL for the zero signal hypothesis and the value at its minimum. For modes with a significance below 5 standard deviations, we quote a 90% confidence level upper limit, corresponding to the branching fraction below which lies 90% of the total of the likelihood integral, in the region where the branching fraction is positive. The correlated and uncorrelated systematic uncertainties are taken into account in the above evaluations by convolving the like-lihood function given by the fitter with a Gaussian function
TABLE II. Signal yield Y and its statistical uncertainty, bias Y0, detection efficiency , daughter branching fraction productQBi,
significance S (with systematic uncertainties included), measured branching fraction B with statistical and systematic errors, 90% confidence level upper limit, and charge asymmetryAch. In the case of 0f0, the quoted branching fraction is the product ofBðB0!
0f0Þ with Bðf0! Þ, which is not well known.
Mode Y (events) Y0(events) (%) QBi(%) S () B (106) B upper limit (106) Ach
00 37 15 9 5 23.4 17.5 2.0 1:5 0:8 0:3 2.8 0f0 8 8 4 2 25.9 17.5 0.5 0:2þ0:40:3 0:1 0.9 0þ 128 22 15 8 14.3 17.5 5.8 9:7þ1:91:8 1:1 0:26 0:17 0:02 0Kð892Þ0 4.0 3:1þ0:90:8 0:3 4.4 0:02 0:23 0:02 0Kð892Þ0 28 10 4 2 18.9 11.7 2.7 2:4þ1:10:9 0:3 0:04 0:35 0Kð892Þ0 61 18 9 5 13.3 19.6 3.1 4:3þ1:61:5 0:5 0:06 0:29 0Kð892Þþ 3.8 4:8þ1:61:4 0:8 7.2 0:26 0:27 0:02 0Kð892ÞþKþ0 14 8 2 1 11.5 5.8 2.0 3:9þ3:12:1 0:5 1:00 0:78 0Kð892ÞþKþ0 26 19 6 3 9.7 9.8 1.1 4:7þ4:54:1 1:3 0:05 0:66 0Kð892ÞþK0 Sþ 23 10 3 2 19.1 4.0 2.6 5:5þ2:92:4 0:7 0:47 0:37 0Kð892ÞþK0 Sþ 34 15 10 5 16.2 6.8 1.6 4:8þ3:22:8 1:2 0:24 0:44 0ðKÞ00 5.6 7:4þ1:51:4 0:6 0:19 0:17 0:02 0ðKÞ00 106 21 12 6 20.2 11.7 4.9 8:5þ2:01:9 1:0 0:39 0:20 0ðKÞ00 115 36 21 11 17.6 19.6 2.7 5:8þ2:32:2 1:0 0:32 0:31 0ðKÞþ0 2.9 6:0þ2:22:0 0:9 9.3 0:06 0:20 0:02 0ðKþ0Þþ0 36 15 2 1 13.9 5.8 2.4 8:8þ4:23:8 1:3 0:00 0:41 0ðKþ0Þþ0 185 51 31 15 12.8 9.8 2.8 26:4þ9:08:5 5:9 0:23 0:27 0ðK0SþÞ0þ 18 12 1 1 18.6 4.0 1.6 5:1þ3:53:2 0:9 0:13 0:59 0ðK0SþÞþ0 29 22 8 4 17.4 6.8 3:8þ4:03:9 1:5 0:40 1:48 0K2ð1430Þ0 5.3 13:7þ3:02:9 1:2 0:14 0:18 0:02 0K2ð1430Þ0 42 13 2 1 15.1 5.8 3.7 9:8þ3:43:2 0:9 0:58 0:32 0K2ð1430Þ0 125 26 20 10 10.6 9.8 4.1 21:7þ5:45:3 3:0 0:05 0:20 0K2ð1430Þþ 7.2 28:0þ4:64:3 2:6 0:15 0:13 0:02 0K2ð1430ÞþKþ0 42 11 5 3 9.9 2.9 3.5 27:1þ8:88:1 4:5 0:29 0:25 0K2ð1430ÞþKþ0 115 28 20 10 8.5 4.9 2.9 46:2 þ14:4 13:8 12:2 0:33 0:24 0K2ð1430ÞþK0Sþ 42 10 5 2 15.3 2.0 4.5 25:9þ7:87:1 2:7 0:44 0:23 0K2ð1430ÞþKS0þ 62 16 14 7 12.4 3.4 3.0 24:1þ8:78:0 4:1 0:22 0:25
P. DEL AMO SANCHEZ et al. PHYSICAL REVIEW D 82, 011502(R) (2010)
representing the systematic uncertainties. The results are collected in TableII.
We show in Fig.1the data and the fit functions projected over the variable mES, while in Fig.2we do the same for the and K invariant masses and for cosH. In these plots the signals are enhanced by the imposition of cuts on lnL and the fit variables, which retain 40%–65% of the signal events.
We evaluate the systematic uncertainties due to the modeling of the signal PDFs by varying the relevant pa-rameters by their uncertainty, derived from the consistency of fits to the above mentioned data control samples. The fit bias arises mostly from correlations among the fit varia-bles, which are modeled by the MC; the associated uncer-tainty is the sum in quadrature of half the correction itself and its statistical uncertainty; this is the dominant source in most cases (2.1–15.4 events), especially for the 0! 0 modes. We verify that the correlations among the variables in SXF events are the major source of bias by performing a dedicated study on simulated experiments in which the SXF component is not embedded. The uncertainty for the SXF fraction is estimated by varying the fraction predicted by the MC by 2.5% (5%) relative for each photon (0) in the final state (most of this uncertainty originates from the simulation of neutral particles). We estimate the uncer-tainty on the charmless B B background by repeating the fit with the yield of this component varied by its estimated
uncertainty ( 20%). For the S-wave K components, we
0 5 10 0 5 10 0 20 40 60 0 20 40 60 (GeV) ES m 5.25 5.26 5.27 5.28 5.29 0 10 20 (GeV) ES m 5.25 5.26 5.27 5.28 5.29 0 10 20 (GeV) ES m 5.25 5.26 5.27 5.28 5.29 0 10 20 30 40 (GeV) ES m 5.25 5.26 5.27 5.28 5.29 0 10 20 30 40 ) c ( ) a ( ) d ( ) b (
Events / 2.5 MeV Events / 2.5 MeV
FIG. 1 (color online). B-candidate mES projections for
(a) 00=0f0, (b) 0þ, (c) 0K0, (d) 0Kþ. Color online:
the solid curve is the fit function, black long-dash-dotted is the total background, and the blue dashed curve is the total signal contribution. In (a) we separate the 0component (red dashed) from the f0(green dotted). In (c, d) we separate the Kð892Þ (red
dashed), theðKÞ0(green dotted), and K2ð1430Þ (magenta
dot-dashed) components. (GeV) π π m 0.6 0.8 1.0 0 2 4 6 8 (GeV) π π m 0.6 0.8 1.0 0 2 4 6 8 (GeV) π K m 0.8 1.0 1.2 1.4 0 20 40 60 80 (GeV) π K m 0.8 1.0 1.2 1.4 0 20 40 60 80 (GeV) π π m 0.6 0.8 1.0 0 5 10 15 (GeV) π π m 0.6 0.8 1.0 0 5 10 15 (GeV) π K m 0.8 1.0 1.2 1.4 0 20 40 (GeV) π K m 0.8 1.0 1.2 1.4 0 20 40 | H θ |cos 0.0 0.2 0.4 0.6 0.8 0 2 4 6 8 | H θ |cos 0.0 0.2 0.4 0.6 0.8 0 2 4 6 8 H θ cos -0.5 0.0 0.5 1.0 0 20 40 60 80 H θ cos -0.5 0.0 0.5 1.0 0 20 40 60 80 H θ cos -0.5 0.0 0.5 1.0 0 10 20 H θ cos -0.5 0.0 0.5 1.0 0 10 20 H θ cos -0.5 0.0 0.5 1.0 0 20 40 60 H θ cos -0.5 0.0 0.5 1.0 0 20 40 60 ) d ( ) b ( ) c ( ) a ( ) h ( ) g ( ) f ( ) e (
Events / 25 MeV Events / 25 MeV Events / 50 MeV Events / 50 MeV
Events / 0.05 Events / 0.1 Events / 0.185 Events / 0.125
FIG. 2 (color online). Top row: B-candidate mprojections for (a) 00=0f0, (b) 0þ, and mKfor (c) 0K0, (d) 0Kþ; on the
bottom row, we plot the cosine of the helicity angle H for (e) 00=0f0, (f ) 0þ, (g) 0K0, and (h) 0Kþ. Color online: the solid
curve is the fit function, the black long-dash-dotted is the total background, and the blue dashed curve is the total signal contribution. In (a) we separate the 0component (red dashed) from the f0(green dotted). In (c, d) we separate the Kð892Þ (red dashed), the ðKÞ0
(green dotted), and K2ð1430Þ (magenta dot-dashed) components.
vary the LASS parameters by the uncertainties found in [19] (the resulting uncertainties vary from 0.1 to 14.9 events).
Multiplicative systematic uncertainties (which do not affect the signal significance) account for imperfect knowl-edge of the luminosity, tracking efficiency, 0 and K0S reconstruction efficiencies, and the uncertainty on the measured branching fractions of intermediate resonances. In the nominal fit we do not account for interference among the different spin K components. We estimate in a sepa-rate calculation, which takes into account the acceptance functions of our analysis, the potential impact of interfer-ence when the relative strong phases between the compo-nents are varied over the full range; we find that the uncertainties range from 1.5% to 14.1%.
From the analysis of a variety of data control samples, the bias on Ach is found to be negligible for pions and 0:01 for kaons, due to differences of Kþ and K inter-actions in the detector material. We correct the fittedAch byþ0:01 in the modes where a charged kaon is present and assign a systematic uncertainty of 0.02, mainly due to the bias correction.
In conclusion, we have measured the branching fraction of B mesons to nine different final states; we claim obser-vation of four of these, while we obtain robust evidence for several others. We compute the branching fraction for 0K0ð1430Þ using the composition of ðKÞ0 from [20].
We find BðB0! 0K0ð1430Þ0Þ ¼ ð6:3 1:3 0:5 0:7Þ 106 and BðBþ! 0K
0ð1430ÞþÞ ¼ ð5:2 1:9 0:8 0:6Þ 106, where the third error comes from the uncertainty in the K0ð1430Þ ! K branching fraction [14]. No significant direct CP violation is seen in the investigated channels. Our results are consistent with and supersede those reported in [7]. Our measured branching fraction for Bþ! 0þ favors the predictions based on pQCD and QCDF over those based on SCET. As in the
B ! !K case, we observe an enhancement of the tensor
K2ð1430Þ over the vector Kð892Þ; this has not been an-ticipated by the theoretical calculations.
We are grateful for the excellent luminosity and machine conditions provided by our PEP-II colleagues, and for the substantial effort from the computing organizations that support BABAR. The collaborating institutions wish to thank SLAC for its support and kind hospitality. This work is supported by DOE and NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3 (France), BMBF and DFG (Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MES (Russia), MICIIN (Spain), and STFC (United Kingdom). Individuals have received support from the Marie Curie EIF (European Union), the A. P. Sloan Foundation (USA), the Binational Science Foundation (USA-Israel), and the University of Colorado at Boulder Graduate School.
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