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Direct top-quark width measurement at CDF

Physical Review Letters 105:23 (2010)

Authors:

T Aaltonen, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, JA Appel, A Apresyan, T Arisawa, A Artikov, J Asaadi, W Ashmanskas, B Auerbach, A Aurisano, F Azfar, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, P Barria, P Bartos, M Bauce, G Bauer, F Bedeschi, D Beecher, S Behari, G Bellettini, J Bellinger, D Benjamin, A Beretvas, A Bhatti, M Binkley, D Bisello, I Bizjak, KR Bland, C Blocker, B Blumenfeld, A Bocci, A Bodek, D Bortoletto, J Boudreau, A Boveia, B Brau, L Brigliadori, A Brisuda, C Bromberg, E Brucken, M Bucciantonio, J Budagov, HS Budd, S Budd, K Burkett, G Busetto, P Bussey, A Buzatu, S Cabrera, C Calancha, S Camarda, M Campanelli, M Campbell, F Canelli, A Canepa, B Carls, D Carlsmith, R Carosi, S Carrillo, S Carron, B Casal, M Casarsa, A Castro, P Catastini, D Cauz, V Cavaliere, M Cavalli-Sforza, A Cerri, L Cerrito, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, K Cho, D Chokheli, JP Chou, WH Chung, YS Chung, CI Ciobanu, MA Ciocci, A Clark, D Clark, G Compostella, ME Convery, J Conway, M Corbo, M Cordelli, CA Cox, DJ Cox, F Crescioli

Abstract:

We present a measurement of the top-quark width in the lepton+jets decay channel of tt̄ events produced in pp̄ collisions at Fermilab's Tevatron collider and collected by the CDF II detector. From a data sample corresponding to 4.3fb⊃-1 of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of the hadronically decaying W boson that comes from the top-quark decay are reconstructed for each event and compared with templates of different top-quark widths (Γt) and deviations from nominal jet energy scale (ΔJES) to perform a simultaneous fit for both parameters, where ΔJES is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of Γt<7.6GeV and a two-sided 68% CL interval of 0.3GeV<Γt<4.4GeV for a top-quark mass of 172.5GeV/c2, which are consistent with the standard model prediction. © 2010 The American Physical Society.
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CMS tracking performance results from early LHC operation

European Physical Journal C 70:4 (2010) 1165-1192

Authors:

V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, J Hammer, S Hänsel, M Hoch, N Hörmann, J Hrubec, M Jeitler, G Kasieczka, W Kiesenhofer, M Krammer, D Liko, I Mikulec, M Pernicka, H Rohringer, R Schöfbeck, J Strauss, A Taurok, F Teischinger, W Waltenberger, G Walzel, E Widl, CE Wulz, V Mossolov, N Shumeiko, J Suarez Gonzalez, L Benucci, L Ceard, EA De Wolf, X Janssen, T Maes, L Mucibello, S Ochesanu, B Roland, R Rougny, M Selvaggi, H Van Haevermaet, P Van Mechelen, N Van Remortel, V Adler, S Beauceron, S Blyweert, J D'Hondt, O Devroede, A Kalogeropoulos, J Maes, M Maes, S Tavernier, W Van Doninck, P Van Mulders, I Villella, EC Chabert, O Charaf, B Clerbaux, G De Lentdecker, V Dero, APR Gay, GH Hammad, PE Marage, C Vander Velde, P Vanlaer, J Wickens, S Costantini, M Grunewald, B Klein, A Marinov, D Ryckbosch, F Thyssen, M Tytgat, L Vanelderen, P Verwilligen, S Walsh, N Zaganidis, S Basegmez, G Bruno, J Caudron, J De Favereau De Jeneret, C Delaere, P Demin, D Favart, A Giammanco, G Grégoire, J Hollar, V Lemaitre, O Militaru, S Ovyn, D Pagano, A Pin, K Piotrzkowski, L Quertenmont, N Schul

Abstract:

The first LHC pp collisions at centre-of-mass energies of 0.9 and 2.36 TeV were recorded by the CMS detector in December 2009. The trajectories of charged particles produced in the collisions were reconstructed using the all-silicon Tracker and their momenta were measured in the 3.8 T axial magnetic field. Results from the Tracker commissioning are presented including studies of timing, efficiency, signal-to-noise, resolution, and ionization energy. Reconstructed tracks are used to benchmark the performance in terms of track and vertex resolutions, reconstruction of decays, estimation of ionization energy loss, as well as identification of photon conversions, nuclear interactions, and heavy-flavour decays. © 2010 CERN for the benefit of the CMS collaboration.
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Measurement of the WW+WZ production cross section using a matrix element technique in lepton+jets events

Physical Review D - Particles, Fields, Gravitation and Cosmology 82:11 (2010)

Authors:

T Aaltonen, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, JA Appel, A Apresyan, T Arisawa, A Artikov, J Asaadi, W Ashmanskas, B Auerbach, A Aurisano, F Azfar, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, P Barria, P Bartos, M Bauce, G Bauer, F Bedeschi, D Beecher, S Behari, G Bellettini, J Bellinger, D Benjamin, A Beretvas, A Bhatti, M Binkley, D Bisello, I Bizjak, KR Bland, C Blocker, B Blumenfeld, A Bocci, A Bodek, D Bortoletto, J Boudreau, A Boveia, B Brau, L Brigliadori, A Brisuda, C Bromberg, E Brucken, M Bucciantonio, J Budagov, HS Budd, S Budd, K Burkett, G Busetto, P Bussey, A Buzatu, S Cabrera, C Calancha, S Camarda, M Campanelli, M Campbell, F Canelli, A Canepa, B Carls, D Carlsmith, R Carosi, S Carrillo, S Carron, B Casal, M Casarsa, A Castro, P Catastini, D Cauz, V Cavaliere, M Cavalli-Sforza, A Cerri, L Cerrito, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, K Cho, D Chokheli, JP Chou, WH Chung, YS Chung, CI Ciobanu, MA Ciocci, A Clark, D Clark, G Compostella, ME Convery, J Conway, M Corbo, M Cordelli, CA Cox, DJ Cox, F Crescioli

Abstract:

We present a measurement of the WW+WZ production cross section observed in a final state consisting of an identified electron or muon, two jets, and missing transverse energy. The measurement is carried out in a data sample corresponding to up to 4.6fb⊃-1 of integrated luminosity at √s=1.96TeV collected by the CDF II detector. Matrix element calculations are used to separate the diboson signal from the large backgrounds. The WW+WZ cross section is measured to be 17.4±3.3pb in agreement with standard model predictions. A fit to the dijet invariant mass spectrum yields a compatible cross section measurement. © 2010 The American Physical Society.
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Search for rare and forbidden decays of charm and charmed-strange mesons to final states h±e e+

Physical Review D - Particles, Fields, Gravitation and Cosmology 82:9 (2010)

Authors:

P Rubin, N Lowrey, S Mehrabyan, M Selen, J Wiss, J Libby, M Kornicer, RE Mitchell, MR Shepherd, CM Tarbert, D Besson, TK Pedlar, J Xavier, D Cronin-Hennessy, J Hietala, P Zweber, S Dobbs, Z Metreveli, KK Seth, A Tomaradze, T Xiao, S Brisbane, L Martin, A Powell, P Spradlin, G Wilkinson, H Mendez, JY Ge, DH Miller, IPJ Shipsey, B Xin, GS Adams, D Hu, B Moziak, J Napolitano, KM Ecklund, J Insler, H Muramatsu, CS Park, LJ Pearson, EH Thorndike, F Yang, S Ricciardi, C Thomas, M Artuso, S Blusk, R Mountain, T Skwarnicki, S Stone, JC Wang, LM Zhang, G Bonvicini, D Cinabro, A Lincoln, MJ Smith, P Zhou, J Zhu, P Naik, J Rademacker, DM Asner, KW Edwards, K Randrianarivony, G Tatishvili, RA Briere, H Vogel, PUE Onyisi, JL Rosner, JP Alexander, DG Cassel, S Das, R Ehrlich, L Fields, L Gibbons, SW Gray, DL Hartill, BK Heltsley, DL Kreinick, VE Kuznetsov, JR Patterson, D Peterson, D Riley, A Ryd, AJ Sadoff, X Shi, WM Sun, J Yelton

Abstract:

We have searched for flavor-changing neutral current decays and lepton-number-violating decays of D+ and Ds+ mesons to final states of the form h±e e+, where h is either π or K. We use the complete samples of CLEO-c open-charm data, corresponding to integrated luminosities of 818pb-1 at the center-of-mass energy E CM=3.774GeV containing 2.4×106 D+D- pairs and 602pb-1 at ECM=4.170GeV containing 0.6×106 Ds*±Ds pairs. No signal is observed in any channel, and we obtain 90% confidence level upper limits on branching fractions B(D +→π+e+e-)<5. 9×10-6, B(D+→π-e +e+)<1.1×10-6, B(D+→ K+e+e-)<3.0×10-6, B(D +→K-e+e+)<3.5×10 -6, B(Ds+→π+e+e-)<2. 2×10-5, B(Ds+→π-e+e +)<1.8×10-5, B(Ds+→K+e +e-)<5.2×10-5, and B(Ds+→K -e+e+)<1.7×10-5. © 2010 The American Physical Society.
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Search for dijet resonances in 7 TeV pp collisions at CMS

Physical Review Letters 105:21 (2010)

Authors:

V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, J Hammer, S Hänsel, C Hartl, M Hoch, N Hörmann, J Hrubec, M Jeitler, G Kasieczka, W Kiesenhofer, M Krammer, D Liko, I Mikulec, M Pernicka, H Rohringer, R Schöfbeck, J Strauss, A Taurok, F Teischinger, W Waltenberger, G Walzel, E Widl, CE Wulz, V Mossolov, N Shumeiko, J Suarez Gonzalez, L Benucci, L Ceard, EA De Wolf, X Janssen, T Maes, L Mucibello, S Ochesanu, B Roland, R Rougny, M Selvaggi, H Van Haevermaet, P Van Mechelen, N Van Remortel, V Adler, S Beauceron, S Blyweert, J D'Hondt, O Devroede, A Kalogeropoulos, J Maes, M Maes, S Tavernier, W Van Doninck, P Van Mulders, I Villella, EC Chabert, O Charaf, B Clerbaux, G De Lentdecker, V Dero, APR Gay, GH Hammad, T Hreus, PE Marage, L Thomas, C Vander Velde, P Vanlaer, J Wickens, S Costantini, M Grunewald, B Klein, A Marinov, D Ryckbosch, F Thyssen, M Tytgat, L Vanelderen, P Verwilligen, S Walsh, N Zaganidis, S Basegmez, G Bruno, J Caudron, J De Favereau De Jeneret, C Delaere, P Demin, D Favart, A Giammanco, G Grégoire, J Hollar, V Lemaitre, O Militaru, S Ovyn, D Pagano, A Pin

Abstract:

A search for narrow resonances in the dijet mass spectrum is performed using data corresponding to an integrated luminosity of 2.9pb⊃-1 collected by the CMS experiment at the Large Hadron Collider. Upper limits at the 95% confidence level are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately for decays into quark-quark, quark-gluon, or gluon-gluon pairs. The data exclude new particles predicted in the following models at the 95% confidence level: string resonances, with mass less than 2.50 TeV, excited quarks, with mass less than 1.58 TeV, and axigluons, colorons, and E6 diquarks, in specific mass intervals. This extends previously published limits on these models. Copyright © 2010 American Physical Society.
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