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A study of bb̄ production in e+e- collisions at √ = 130-207 GeV

European Physical Journal C 60:1 (2009) 1-15

Authors:

J Abdallah, P Abreu, W Adam, P Adzic, T Albrecht, R Alemany-Fernandez, T Allmendinger, PP Allport, U Amaldi, N Amapane, S Amato, E Anashkin, A Andreazza, S Andringa, N Anjos, P Antilogus, WD Apel, Y Arnoud, S Ask, B Asman, JE Augustin, A Augustinus, P Baillon, A Ballestrero, P Bambade, R Barbier, D Bardin, GJ Barker, A Baroncelli, M Battaglia, M Baubillier, KH Becks, M Begalli, A Behrmann, E Ben-Haim, N Benekos, A Benvenuti, C Berat, M Berggren, D Bertrand, M Besancon, N Besson, D Bloch, M Blom, M Bluj, M Bonesini, M Boonekamp, PSL Booth, G Borisov, O Botner, B Bouquet, TJV Bowcock, I Boyko, M Bracko, R Brenner, E Brodet, P Bruckman, JM Brunet, B Buschbeck, P Buschmann, M Calvi, T Camporesi, V Canale, F Carena, N Castro, F Cavallo, M Chapkin, P Charpentier, P Checchia, R Chierici, P Chliapnikov, J Chudoba, SU Chung, K Cieslik, P Collins, R Contri, G Cosme, F Cossutti, MJ Costa, D Crennell, J Cuevas, J D'Hondt, T Da Silva, W Da Silva, G Della Ricca, A De Angelis, W De Boer, C De Clercq, B De Lotto, N De Maria, A De Min, L De Paula, L Di Ciaccio, A Di Simone, K Doroba, J Drees, G Eigen, T Ekelof, M Ellert, M Elsing

Abstract:

Measurements are presented of R b, the ratio of the cross-section to the cross-section in e+e- collisions, and the forward-backward asymmetry A FBb at twelve energy points in the range sqrt{s}=130-207 GeV. These results are found to be consistent with the Standard Model expectations. The measurements are used to set limits on new physics scenarios involving contact interactions. © 2009 Springer-Verlag / Società Italiana di Fisica.
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Measurement of the fraction of tt̄ production via gluon-gluon fusion in pp̄ collisions at s=1.96TeV

Physical Review D - Particles, Fields, Gravitation and Cosmology 79:3 (2009)

Authors:

T Aaltonen, J Adelman, T Akimoto, MG Albrow, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, A Apresyan, T Arisawa, A Artikov, W Ashmanskas, A Attal, A Aurisano, F Azfar, P Azzurri, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, V Bartsch, G Bauer, PH Beauchemin, F Bedeschi, P Bednar, D Beecher, S Behari, G Bellettini, J Bellinger, D Benjamin, A Beretvas, J Beringer, A Bhatti, M Binkley, D Bisello, I Bizjak, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, D Bortoletto, J Boudreau, A Boveia, B Brau, A Bridgeman, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, K Burkett, G Busetto, P Bussey, A Buzatu, KL Byrum, S Cabrera, C Calancha, M Campanelli, M Campbell, F Canelli, A Canepa, 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, SH Chang, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, CI Ciobanu, MA Ciocci, A Clark, D Clark, G Compostella

Abstract:

We present a measurement of the ratio of the tt̄ production cross section via gluon-gluon fusion to the total tt̄ production cross section in pp̄ collisions at s=1.96TeV at the Tevatron. Using a data sample with an integrated luminosity of 955pb-1 recorded by the CDF II detector at Fermilab, we select events based on the tt̄ decay to lepton+jets. Using an artificial neural network technique we discriminate between tt̄ events produced via qq̄ annihilation and gg fusion, and find Gf=σ(gg→tt̄)/ σ(pp̄→tt̄)<0.33 at the 68% confidence level. This result is combined with a previous measurement to obtain the most stringent measurement of this quantity by CDF to date, Gf=0.07-0.07+0.15. © 2009 The American Physical Society.
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Observation of η′ decays to π+π-π0 and π+π-e+e-

Physical Review Letters 102:6 (2009)

Authors:

P Naik, J Rademacker, DM Asner, KW Edwards, J Reed, AN Robichaud, G Tatishvili, RA Briere, H Vogel, PUE Onyisi, JL Rosner, JP Alexander, DG Cassel, JE Duboscq, R Ehrlich, L Fields, RS Galik, L Gibbons, R Gray, SW Gray, DL Hartill, BK Heltsley, D Hertz, JM Hunt, J Kandaswamy, DL Kreinick, VE Kuznetsov, J Ledoux, H Mahlke-Krüger, D Mohapatra, JR Patterson, D Peterson, D Riley, A Ryd, AJ Sadoff, X Shi, S Stroiney, WM Sun, T Wilksen, SB Athar, J Yelton, P Rubin, S Mehrabyan, N Lowrey, M Selen, EJ White, J Wiss, RE Mitchell, MR Shepherd, D Besson, TK Pedlar, D Cronin-Hennessy, KY Gao, J Hietala, Y Kubota, T Klein, R Poling, AW Scott, P Zweber, S Dobbs, Z Metreveli, KK Seth, BJY Tan, A Tomaradze, J Libby, L Martin, A Powell, G Wilkinson, H Mendez, JY Ge, DH Miller, V Pavlunin, B Sanghi, IPJ Shipsey, B Xin, GS Adams, D Hu, B Moziak, J Napolitano, Q He, J Insler, H Muramatsu, CS Park, EH Thorndike, F Yang, M Artuso, S Blusk, S Khalil, J Li, R Mountain, K Randrianarivony, N Sultana, T Skwarnicki, S Stone, JC Wang, LM Zhang, G Bonvicini, D Cinabro, M Dubrovin, A Lincoln

Abstract:

Using ψ(2S)→π+π-J/ψ, J/ψ→γη′ events acquired with the CLEO-c detector at the CESR e+e- collider, we make the first observations of the decays η′→π+π-π0 and η′→π+π-e+e-, measuring absolute branching fractions (37-9+11±4)×10-4 and (25-9+12±5)×10-4, respectively. For η′→π+π-π0, this result probes the mechanism of isospin violation and the roles of π0/η/η′-mixing and final state rescattering in strong decays. We also set upper limits on branching fractions for η′ decays to π+π-μ+μ-, 2(π+π-), π+π-2π0, 2(π+π-)π0, 3(π+π-), and invisible final states. © 2009 The American Physical Society.
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First measurement of the ratio of branching fractions B(Λb 0→Λc+μ-ν̄μ)/B(Λb 0→Λc+π-)

Physical Review D - Particles, Fields, Gravitation and Cosmology 79:3 (2009)

Authors:

T Aaltonen, J Adelman, T Akimoto, MG Albrow, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, A Apresyan, T Arisawa, A Artikov, W Ashmanskas, A Attal, A Aurisano, F Azfar, P Azzurri, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, V Bartsch, G Bauer, PH Beauchemin, F Bedeschi, D Beecher, S Behari, G Bellettini, J Bellinger, D Benjamin, A Beretvas, J Beringer, A Bhatti, M Binkley, D Bisello, I Bizjak, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, D Bortoletto, J Boudreau, A Boveia, B Brau, A Bridgeman, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, S Burke, K Burkett, G Busetto, P Bussey, A Buzatu, KL Byrum, S Cabrera, C Calancha, 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, SH Chang, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, T Chwalek, CI Ciobanu, MA Ciocci, A Clark

Abstract:

This article presents the first measurement of the ratio of branching fractions B(Λb0→Λc+μ-ν̄μ)/ B(Λb0→Λc+π-). Measurements in two control samples using the same technique B(B̄0→D+μ- ν̄μ)/B(B̄0→D+π-) and B(B̄ 0→D*(2010)+μ-ν̄μ)/ B(B̄0→D*(2010)+π-) are also reported. The analysis uses data from an integrated luminosity of approximately 172pb-1 of pp̄ collisions at s=1.96TeV, collected with the CDF II detector at the Fermilab Tevatron. The relative branching fractions are measured to be B(Λb 0→Λc+μ-ν̄μ)B(Λb 0→Λc+π-)=16.6±3.0(stat) ±1.0(syst)+2.6-3.4(PDG) ±0.3(EBR), B(B̄0→D+μ-ν̄μ) B(B̄0→D+π-)=9.9±1.0(stat) ±0.6(syst)±0.4(PDG)± 0.5(EBR), and B(B̄0→D*( 2010)+μ-ν̄μ)B(B̄0→D*( 2010)+π-)=16.5±2.3(stat) ±0.6(syst)±0.5(PDG)± 0.8(EBR). The uncertainties are from statistics (stat), internal systematics (syst), world averages of measurements published by the Particle Data Group or subsidiary measurements in this analysis (PDG), and unmeasured branching fractions estimated from theory (EBR), respectively. This article also presents measurements of the branching fractions of four new Λb 0 semileptonic decays: Λb0→Λc( 2595)+μ-ν̄μ, Λb0→Λc( 2625)+μ-ν̄μ, Λb0→Σc( 2455)0π+μ-ν̄μ, and Λb 0→Σc(2455)++π-μ-ν̄μ, relative to the branching fraction of the Λb0→Λc+μ- ν̄μ decay. Finally, the transverse-momentum distribution of Λb0 baryons produced in pp̄ collisions is measured and found to be significantly different from that of B̄0 mesons, which results in a modification in the production cross-section ratio σΛb0/σB̄0 with respect to the CDF I measurement. © 2009 The American Physical Society.
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Erratum: Search for high-mass e+e- Resonances in pp̄ collisions at s=1.96TeV (Physical Review Letters (2009) 102 (031801))

Physical Review Letters 102:5 (2009)

Authors:

T Aaltonen, J Adelman, T Akimoto, MG Albrow, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, A Apresyan, T Arisawa, A Artikov, W Ashmanskas, A Attal, A Aurisano, F Azfar, P Azzurri, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, V Bartsch, G Bauer, PH Beauchemin, F Bedeschi, D Beecher, S Behari, G Bellettini, J Bellinger, D Benjamin, A Beretvas, J Beringer, A Bhatti, M Binkley, D Bisello, I Bizjak, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, D Bortoletto, J Boudreau, A Boveia, B Brau, A Bridgeman, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, S Burke, K Burkett, G Busetto, P Bussey, A Buzatu, KL Byrum, S Cabrera, C Calancha, 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, SH Chang, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, T Chwalek, CI Ciobanu, MA Ciocci, A Clark
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