| Autor: |
C. Fitzpatrick, R. Schwemmer, L. Del Buono, Jonas Rademacker, Stephen M. Stahl, Dmitry Golubkov, N. Neufeld, Tatsuya Nakada, Lars Eklund, S. Amerio, G. Valenti, G. Busetto, A. Vollhardt, S. Eidelman, F. Muheim, A. Phan, Ziad Ajaltouni, Christopher John Parkinson, M. Veltri, C. Santamarina Rios, F. Kruse, P. Henrard, O. Shevchenko, P. Owen, T. Head, F. Blanc, G. Manca, O. Schneider, M. Karacson, X. Yuan, G. Martellotti, L. Pescatore, J. Garofoli, Pavel Shatalov, V. Bocci, J. Blouw, O. Leroy, R. Lindner, T. Palczewski, R. Lefèvre, L. Garrido, C. Baesso, I. Nasteva, S. Stevenson, J. Maratas, Valery Pugatch, C. Göbel, J. E. Andrews, M.I. Williams, Y. N. Gao, S. Lohn, Karol Hennessy, O. Maev, P. Seyfert, F. F. Wilson, T. D. Nguyen, A. Richards, A. Pazos Alvarez, A. Satta, A. A. Affolder, G. Veneziano, C. Lazzeroni, V. Shevchenko, W. D. Hulsbergen, C. Farinelli, Mark Whitehead, D. A. Milanes, E. Bowen, A. Bay, V. Egorychev, B. T. Meadows, J. van Leerdam, G. Raven, D. Martins Tostes, D. Decamp, A. Golutvin, M. D. Sokoloff, A. Zhelezov, G. Graziani, P. N. Y. David, J. Wang, C. Barschel, D. A. Roberts, M. Korolev, J. He, Sebastian Bachmann, William Barter, Angelo Carbone, Jaap Velthuis, M. Meissner, M. Fiore, Konstantinos Petridis, E. Santovetti, T. Britton, F. Soomro, F. Zhang, Ph. Charpentier, M. Baalouch, B. Viaud, N. Sagidova, L. Li Gioi, P. Vazquez Regueiro, R. Märki, J. H. Lopes, D. R. Johnson, P. Gandini, K. De Bruyn, F. Polci, M. Adinolfi, A. Jaeger, S. Easo, D. Voong, F. Fontanelli, M. Zangoli, H. Lu, E. Tournefier, V. Obraztsov, R. Silva Coutinho, Dmitry Popov, C. R. Jones, M. Sapunov, Stephan Eisenhardt, G. Penso, Ross D. Young, C. Satriano, R. Le Gac, P. Campana, E. Ben-Haim, G. Auriemma, A. Contu, A. Borgia, E. Perez Trigo, F. F. Jing, U. Eitschberger, G. Mancinelli, J. Closier, F. Dupertuis, P. Alvarez Cartelle, P. Morawski, W. Bonivento, C. Vázquez Sierra, A. Powell, A. Jawahery, Z. Mathe, S. Malde, X. Cid Vidal, C. Gotti, S. Blusk, G. N. Patrick, A. Petrolini, M. Sirendi, S. Swientek, E. Lanciotti, T. M. Karbach, J. Anderson, M. Coombes, G. Alkhazov, Kurt Rinnert, Sandra Amato, Petr Andreevich Gorbounov, M. Witek, K. Belous, K. Carvalho Akiba, S. Furcas, W. Qian, M. Needham, Hans Dijkstra, A. Ustyuzhanin, Alexander Berezhnoy, Mario Sannino, A. Mazurov, B. Popovici, D. Urner, P. Tsopelas, C. Patrignani, V. Tisserand, L. Zhong, Gianluigi Casse, H. Voss, A. Martynov, D. Websdale, B. Couturier, P. Schaack, R. Wallace, C. Adrover, S. Stone, D. Vieira, Th. Bauer, A. Cook, S. Oggero, D. Ferguson, S. Neubert, A. Sparkes, Pietro Marino, C. Linn, B. McSkelly, Alessandro Camboni, G. Polok, I. Mous, F. Maciuc, N. Déléage, Ignacio Bediaga, M. Calvo Gomez, Guoming Liu, A. Shires, B. Souza De Paula, E. Jans, M. S. Rangel, G. Corti, S. Topp-Joergensen, M. Kucharczyk, T. Gys, V. N. La Thi, W. Kanso, A. Di Canto, S. Belogurov, N. Tuning, F. Teubert, J. Lefrançois, T. Bird, J. Serrano, S. Playfer, M. Kaballo, A. Pérez-Calero Yzquierdo, V. Iakovenko, W. C. Zhang, J. McCarthy, P. Durante, M. M. Reid, M. Schlupp, R. Santacesaria, M. Dogaru, Stephane T'Jampens, M. Gandelman, S. T. Harnew, M. Tresch, L. Zhang, Howard Gordon, J. Wishahi, Dermot Moran, E. Greening, Patrick Koppenburg, M. Perrin-Terrin, Marianna Fontana, M. Grabalosa Gándara, R. Currie, M. Shapkin, Pieter David, Y. Shcheglov, D. Hill, W. Baldini, G. Carboni, A. Leflat, J. Molina Rodriguez, E. Gushchin, R. F. Koopman, C. Haen, C. Hadjivasiliou, Maurizio Martinelli, M. Szczekowski, S. Borghi, M. J.J. John, N. Rauschmayr, R. Nandakumar, D. van Eijk, M. Hess, R. Andreassen, M. J. Charles, A. Davis, J. Beddow, J. P. Lees, B. Rakotomiaramanana, J. Wimberley, T. Kvaratskheliya, D. E. Hutchcroft, Anton Poluektov, N. Torr, V. Gibson, S. De Capua, D. Dossett, T. J. V. Bowcock, A. Palano, Tomasz Szumlak, O. Yushchenko, E. Furfaro, D. Martinez Santos, S. Perazzini, K. Ciba, Patrick Robbe, M. J. Morello, P. Perret, O. Aquines Gutierrez, Sergey Barsuk, C. Joram, H. Ruiz, M. Orlandea, Michal Kreps, B. Jost, C. Coca, Nikolay Nikitin, O. Steinkamp, Plamen Hristov Hopchev, I. Raniuk, S. Hansmann-Menzemer, A. Schopper, R. Mountain, M. Deckenhoff, J. J. Saborido Silva, P. Rodriguez Perez, A. Nomerotski, Sandro Cadeddu, F. J. P. Soler, M. Seco, M. P. Williams, M. Ubeda Garcia, O. Callot, I. Shapoval, M. Britsch, L. Carson, A. Martín Sánchez, P. Griffith, B. Leverington, M. Chrzaszcz, S. Donleavy, L. Giubega, E. Cogneras, C. Bozzi, K. Senderowska, G. Fardell, C. Voß, L. Castillo Garcia, A. D. Nguyen, Francesco Dettori, S. Ali, Marco Clemencic, Luyan Sun, J. G. Cogan, S. C. Haines, A. Hicheur, D. Lacarrere, A. Mordà, S. A. Wotton, J. M. Otalora Goicochea, R. Waldi, Rudolf Oldeman, T. Lesiak, J. Wiechczynski, Zishuo Yang, C. Gaspar, M. Palutan, M. Teklishyn, M. O. Bettler, V. V. Gligorov, R. Muresan, N. A. Smith, E. van Herwijnen, R. Ekelhof, A. Tsaregorodtsev, T. Ruf, Y. Li, G. Lanfranchi, M.-N. Minard, C. Langenbruch, B. Storaci, A.E. Bondar, M. Hoballah, G. Ciezarek, J. G. Smith, J. Wicht, A. Bien, A. A. Alves, G. D. Patel, E. Teodorescu, A. Falabella, Biagio Saitta, G. Krocker, E. Thomas, R. Niet, R. Vazquez Gomez, G. Punzi, A. Vorobyev, F. Dordei, Michael Alexander, S. Farry, P. E. L. Clarke, A. Kozlinskiy, R. Jacobsson, A. Dovbnya, C. Wallace, Emilie Maurice, Manuel Schiller, I. De Bonis, J. Bressieux, Andrea Bizzeti, E. Gersabeck, A. Gallas Torreira, C. Färber, B. Muryn, H. Carranza-Mejia, R. J. Barlow, Roland Bernet, E. Picatoste Olloqui, S. Wandernoth, A. Bursche, D. C. Craik, P. M. Bjørnstad, D. Souza, P. Naik, P. Ilten, S. Stoica, A. C. dos Reis, T. Brambach, Alessio Sarti, L. Shekhtman, A. Dosil Suárez, L. Kravchuk, Alessandro Cardini, J. M. De Miranda, S. Ogilvy, I. Komarov, B. Gui, R. Dzhelyadin, A. Lai, R. Cenci, Marta Calvi, A. Zvyagin, P. Szczypka, S. Ricciardi, S. Redford, M. Schmelling, N. Lopez-March, M. Nicol, R. Matev, E. Rodrigues, A. Zhokhov, L. De Paula, Y. Xie, Thomas Blake, H. Schindler, Marek Idzik, P. Ruiz Valls, Christoph Frei, F. Meier, I. R. Kenyon, M. Pappagallo, D. Pinci, M. Vesterinen, Nicola Serra, B. Schmidt, Roger Forty, S. Hall, A. Keune, P. Garosi, J. Benton, M. De Cian, M. van Beuzekom, T. Huse, M. Zavertiaev, Victor Coco, Albert Comerma-Montells, V. Syropoulos, V. K. Subbiah, V. Romanovsky, D. Wiedner, A. D. Webber, Ivan Belyaev, P. Sail, B. Adeva, D. Hynds, D. Galli, Denis Derkach, G. Sabatino, G. D. Lafferty, M. Frank, U. Marconi, M. Van Dijk, K. Kurek, O. Grünberg, A. Artamonov, M. Pepe Altarelli, F. Ferreira Rodrigues, W. Wislicki, V. Rives Molina, Y. Zhang, T. Nikodem, T. Pilař, Marina Artuso, F. Stagni, V. Vagnoni, T. E. Latham, J. Rouvinet, A. Puig Navarro, Marco Gersabeck, D. Campora Perez, V. Salustino Guimaraes, H. Brown, Jan Buytaert, S. Cunliffe, T. G. Shears, H. V. Cliff, S. Leo, M. Plo Casasus, Federico Alessio, Nikolay Bondar, A. Romero Vidal, P. Jaton, C. Thomas, K. Müller, D. A. Roa Romero, V. Kudryavtsev, D. R. Ward, B. X. Liu, W. De Silva, G. Passaleva, T. Hartmann, J. Luisier, Lucio Anderlini, Oscar De Aguiar Francisco, D. Lambert, Ch. Elsasser, R. McNulty, O. Okhrimenko, P. Krokovny, Ph. Ghez, A. Sciubba, S. Tourneur, G. Wilkinson, M. T. Tran, R. Gauld, J. F. J. van den Brand, V. Fernandez Albor, V. Niess, A. Popov, N. Hussain, A. Semennikov, D. Brett, E. Grauges, L. Wiggers, I. Burducea, A. Gomes, A. Dzyuba, Simone Bifani, G. Haefeli, N. Chiapolini, J. Marks, F. Machefert, C. Hombach, C. Matteuzzi, I. V. Machikhiliyan, K. Kreplin, M. Liles, E. Pesen, J. Panman, C. Nguyen-Mau, T. J. Gershon, D. Volyanskyy, A. Papanestis, L. A. Granado Cardoso, N. H. Brook, Stephane Monteil, Elie Aslanides, S. Gregson, A. Grecu, J. Albrecht, J. J. Back, Ch. Cauet, M. Straticiuc, J. van Tilburg, G. A. Cowan, C. Parkes, F. Ruffini, D. Lucchesi, I. Longstaff, K. Wyllie, B. Pietrzyk, J. Harrison, I. Sepp, M. Merk, Tjeerd Ketel, M. N. K. Smith, M. Frosini, D. Savrina, Z. Xing, Yu. Guz, R. W. Lambert, Roberta Cardinale, Vladislav Balagura, O. Kochebina, P. Spradlin, J. Prisciandaro, S. Roiser, P. De Simone, I. El Rifai, M. Savrie, B. Spaan, V. Heijne, J. Garra Tico, A. Massafferri, J. A. Hernando Morata, Roel Aaij, Po-Hsun Chen, C. Prouve, A. Martens, Xavier Vilasis-Cardona, M. Patel, N. K. Watson, D. Tonelli, S. Wright, A. Ukleja, A. Novoselov, B. Khanji, U. Egede, H. Luo, Antonio Pellegrino, B. Hamilton, Sean Benson, S. Wu, U. Straumann, S. Coquereau, E. Polycarpo, Olivier Deschamps, Flavio Archilli, A. Pritchard, G. Bencivenni, Marco Cattaneo, Agnieszka Oblakowska-Mucha, A. I. McNab, C. Pavel-Nicorescu, S. Filippov, E. Hicks, M. Tobin, T. Hampson, V. Vorobyev, Franco Bedeschi, A. Oyanguren, B. K. Pal, R. B. Appleby, M. Ferro-Luzzi, B. Sanmartin Sedes, Barbara Sciascia, B. Muster, S. Tolk, T. Skwarnicki, E. Smith, P. Hunt, S. Vecchi, P. Collins, Yasmine Amhis, S. Kandybei, A. Dziurda, R. Graciani Diaz, M. H. Schune, Neville Harnew, U. Uwer, A. Vallier, C. Potterat, Carmelo D'Ambrosio |
| Rok vydání: |
2013 |
| Předmět: |
|
| Zdroj: |
Physical Review Letters. 111 |
| ISSN: |
1079-7114
0031-9007 |
| Popis: |
PRL 111, 181801 (2013) PHYSICAL REVIEW LETTERS week ending 1 NOVEMBER 2013 Observation of the Decay B þ c ! B s R. Aaij et al. * (LHCb Collaboration) (Received 22 August 2013; published 1 November 2013) The result of a search for the decay B þ c ! B s is presented, using the B s ! D s and B s ! J= c channels. The analysis is based on a data sample of pp collisions collected with the LHCb detector, corresponding to an integrated luminosity of 1 fb 1 taken at a center-of-mass energy of 7 TeV, and 2 fb 1 taken at 8 TeV. The decay B þ c ! B s is observed with significance in excess of 5 standard deviations independently in both decay channels. The measured product of the ratio of cross sections and branching Þ 10 3 , in fraction is ½ðB þ c Þ=ðB s Þ BðB c ! B s Þ ¼ ½2:37 0:31 ðstatÞ 0:11 ðsystÞ 0:13 ð B þ c the pseudorapidity range 2 < ðBÞ < 5, where the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the B þ c lifetime. This is the first observation of a B meson decaying to another B meson via the weak interaction. DOI: 10.1103/PhysRevLett.111.181801 PACS numbers: 13.25.Hw, 12.15.Ji The B þ c meson is the ground state of the bc system. As such it is unique as it is the only weakly decaying doubly heavy meson. All measurements of B þ c meson decays to date are decays where the constituent b quark decays weakly to a c quark [1–8]. The decay of the B þ c meson to another B meson, with the bottom quark acting as a spectator (see Fig. 1), has not previously been observed. This will improve the understanding of theoretical predic- tions and provide valuable information for the source of B 0 s mesons at the LHC. A wide range of predictions for the branching fraction BðB þ c ! B s Þ exists, between 16.4% and 2.5%, based on, e.g., QCD sum rules [9,10], or quark-potential models (see Refs. [11–16] and references therein). Experimental clarification is needed to shed light on the present theoreti- cal status. Unlike most other B decays, the higher order corrections in the expansion of Heavy Quark Effective Theory within the framework of quantum chromodynam- ics (QCD) are relatively large. The expansion is described in powers of m c =m b rather than QCD =m b , due to the presence of two heavy quark constituents, where QCD is the QCD scale, and m c (m b ) the charm (bottom) quark mass. In addition, the energy release in the decay is rela- tively small, leading to larger nonfactorizable effects com- pared to decays with lighter daughter particles. Study of the decay B þ c ! B s allows these models to be tested. Knowledge of the production of B 0 s mesons from B þ c decays is also useful for time-dependent analyses of B 0 s decays, to understand any associated decay-time bias due to the incorrect estimate of the B 0 s decay time if originating from a B þ c decay, or to take advantage of flavor tagging capabilities using the accompanying (‘‘bachelor’’) pion. The data used in this analysis were collected with the p ffiffiffi LHCb detector [17] from pp collisions at s ¼ 7 TeV and 8 TeV, corresponding to integrated luminosities of 1 fb 1 and 2 fb 1 , respectively. The decays B 0 s ! D and B 0 s ! J= c are used, s with the subsequent decays D s ! K K , J= c ! and ! K K . The inclusion of charge conju- gate modes is implied throughout. The event selection and fits to the B 0 s invariant mass distributions follow previous LHCb analyses based on these B 0 s decay modes [18,19]. The two channels are analyzed independently and the final results are combined. The strategy is to normalize the final number of B þ decays to the number of B 0 s c ! B s decays, which gives a result for the B þ c ! B s branching fraction multiplied by the ratio of B c and B 0 s production rates, ½ðB þ c Þ=ðB s Þ BðB c ! B s Þ. The B c signal *Full author list given at end of the article. Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distri- bution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. FIG. 1. Leading-order Feynman diagram of the decay B þ c ! B s . O 2013 CERN, for the LHCb Collaboration |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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