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Measurement of the mass difference between top and antitop quarks

Physical Review D - Particles, Fields, Gravitation and Cosmology 87:5 (2013)

Authors:

T Aaltonen, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, JA Appel, T Arisawa, A Artikov, J Asaadi, W Ashmanskas, B Auerbach, A Aurisano, F Azfar, W Badgett, T Bae, A Barbaro-Galtieri, VE Barnes, BA Barnett, P Barria, P Bartos, M Bauce, F Bedeschi, S Behari, G Bellettini, J Bellinger, D Benjamin, A Beretvas, A Bhatti, KR Bland, B Blumenfeld, A Bocci, A Bodek, D Bortoletto, J Boudreau, A Boveia, L Brigliadori, C Bromberg, E Brucken, J Budagov, HS Budd, K Burkett, G Busetto, P Bussey, P Butti, A Buzatu, A Calamba, S Camarda, M Campanelli, F Canelli, B Carls, D Carlsmith, R Carosi, S Carrillo, 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, K Cho, D Chokheli, MA Ciocci, A Clark, C Clarke, ME Convery, J Conway, M Corbo, M Cordelli, CA Cox, DJ Cox, M Cremonesi, D Cruz, J Cuevas, R Culbertson, N D'Ascenzo, M Datta, P De Barbaro, L Demortier, M Deninno, F Devoto, M D'Errico, A Di Canto, B Di Ruzza, JR Dittmann, M D'Onofrio, S Donati, M Dorigo, A Driutti, K Ebina, R Edgar, A Elagin

Abstract:

We present a measurement of the mass difference between top (t) and antitop (t̄) quarks using tt̄ candidate events reconstructed in the final state with one lepton and multiple jets. We use the full data set of Tevatron √s=1.96 TeV proton-antiproton collisions recorded by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb-1. We estimate event by event the mass difference to construct templates for top pair signal events and background events. The resulting mass difference distribution in data compared to signal and background templates using a likelihood fit yields ΔMtop=Mt-Mt̄=-1.95±1.11(stat) ±0.59(syst) GeV/c2 and is in agreement with the standard model prediction of no mass difference. © 2013 American Physical Society.
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Search for a two-higgs-boson doublet using a simplified model in pp̄ collisions at √s=1.96 TeV

Physical Review Letters 110:12 (2013)

Authors:

T Aaltonen, J Adelman, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, JA Appel, T Arisawa, A Artikov, J Asaadi, W Ashmanskas, B Auerbach, A Aurisano, F Azfar, W Badgett, T Bae, A Barbaro-Galtieri, VE Barnes, BA Barnett, P Barria, P Bartos, M Bauce, F Bedeschi, S Behari, G Bellettini, J Bellinger, D Benjamin, A Beretvas, A Bhatti, D Bisello, I Bizjak, KR Bland, B Blumenfeld, A Bocci, A Bodek, D Bortoletto, J Boudreau, A Boveia, L Brigliadori, C Bromberg, E Brucken, J Budagov, HS Budd, K Burkett, G Busetto, P Bussey, A Buzatu, A Calamba, C Calancha, S Camarda, M Campanelli, M Campbell, F Canelli, 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, WH Chung, YS Chung, MA Ciocci, A Clark, C Clarke, G Compostella, ME Convery, J Conway, M Corbo, M Cordelli, CA Cox, DJ Cox, F Crescioli, J Cuevas, R Culbertson, D Dagenhart, N D'Ascenzo, M Datta, P De Barbaro, M Dell'Orso, L Demortier, M Deninno, F Devoto

Abstract:

We present a search for new particles in an extension to the standard model that includes a heavy Higgs boson (H0), a lighter charged Higgs boson (H ±), and an even lighter Higgs boson h0, with decays leading to a W-boson pair and a bottom-antibottom quark pair in the final state. We use events with exactly one lepton, missing transverse momentum, and at least four jets in data corresponding to an integrated luminosity of 8.7 fb-1 collected by the CDF II detector in proton-antiproton collisions at √s=1.96 TeV. We find the data to be consistent with standard model predictions and report the results in terms of a simplified Higgs-cascade-decay model, setting 95% confidence level upper limits on the product of cross section and branching fraction from 1.3 pb to 15 fb as a function of H0 and H ± masses for mh0=126 GeV/c2. © 2013 American Physical Society.
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Measurement of the cross section for prompt isolated diphoton production using the full CDF run II data sample

Physical Review Letters 110:10 (2013)

Authors:

T Aaltonen, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, JA Appel, T Arisawa, A Artikov, J Asaadi, W Ashmanskas, B Auerbach, A Aurisano, F Azfar, W Badgett, T Bae, A Barbaro-Galtieri, VE Barnes, BA Barnett, P Barria, P Bartos, M Bauce, F Bedeschi, S Behari, G Bellettini, J Bellinger, D Benjamin, A Beretvas, A Bhatti, KR Bland, B Blumenfeld, A Bocci, A Bodek, D Bortoletto, J Boudreau, A Boveia, L Brigliadori, C Bromberg, E Brucken, J Budagov, HS Budd, K Burkett, G Busetto, P Bussey, P Butti, A Buzatu, A Calamba, S Camarda, M Campanelli, F Canelli, B Carls, D Carlsmith, R Carosi, S Carrillo, 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, K Cho, D Chokheli, MA Ciocci, A Clark, C Clarke, ME Convery, J Conway, M Corbo, M Cordelli, CA Cox, DJ Cox, M Cremonesi, D Cruz, J Cuevas, R Culbertson, N D'Ascenzo, M Datta, P De Barbaro, L Demortier, M Deninno, F Devoto, M D'Errico, A Di Canto, B Di Ruzza, JR Dittmann, M D'Onofrio, S Donati, M Dorigo, A Driutti, K Ebina, R Edgar, A Elagin

Abstract:

This Letter reports a measurement of the cross section for producing pairs of central prompt isolated photons in proton-antiproton collisions at a total energy √s=1.96 TeV using data corresponding to 9.5 fb-1 integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. The measured differential cross section is compared to three calculations derived from the theory of strong interactions. These include a prediction based on a leading order matrix element calculation merged with a parton shower model, a next-to-leading order calculation, and a next-to-next-to-leading order calculation. The first and last calculations reproduce most aspects of the data, thus showing the importance of higher-order contributions for understanding the theory of strong interaction and improving measurements of the Higgs boson and searches for new phenomena in diphoton final states. © 2013 American Physical Society.
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Observation of D0-D̄0 oscillations

Physical Review Letters 110:10 (2013)

Authors:

R Aaij, C Abellan Beteta, A Adametz, B Adeva, M Adinolfi, C Adrover, A Affolder, Z Ajaltouni, J Albrecht, F Alessio, M Alexander, S Ali, G Alkhazov, P Alvarez Cartelle, AA Alves, S Amato, Y Amhis, L Anderlini, J Anderson, R Andreassen, RB Appleby, O Aquines Gutierrez, F Archilli, A Artamonov, M Artuso, E Aslanides, G Auriemma, S Bachmann, JJ Back, C Baesso, W Baldini, RJ Barlow, C Barschel, S Barsuk, W Barter, A Bates, T Bauer, A Bay, J Beddow, I Bediaga, S Belogurov, K Belous, I Belyaev, E Ben-Haim, M Benayoun, G Bencivenni, S Benson, J Benton, A Berezhnoy, R Bernet, MO Bettler, M Van Beuzekom, A Bien, S Bifani, T Bird, A Bizzeti, PM Bjørnstad, T Blake, F Blanc, C Blanks, J Blouw, S Blusk, A Bobrov, V Bocci, A Bondar, N Bondar, W Bonivento, S Borghi, A Borgia, TJV Bowcock, E Bowen, C Bozzi, T Brambach, J Van Den Brand, J Bressieux, D Brett, M Britsch, T Britton, NH Brook, H Brown, A Büchler-Germann, I Burducea, A Bursche, J Buytaert, S Cadeddu, O Callot, M Calvi, M Calvo Gomez, A Camboni, P Campana, A Carbone, G Carboni, R Cardinale, A Cardini, H Carranza-Mejia, L Carson, K Carvalho Akiba, G Casse, M Cattaneo, C Cauet

Abstract:

We report a measurement of the time-dependent ratio of D0→K +π- to D0→K-π+ decay rates in D*+-tagged events using 1.0 fb-1 of integrated luminosity recorded by the LHCb experiment. We measure the mixing parameters x′2=(-0.9±1.3)×10-4, y′=(7.2±2.4)×10-3, and the ratio of doubly-Cabibbo-suppressed to Cabibbo-favored decay rates RD=(3. 52±0.15)×10-3, where the uncertainties include statistical and systematic sources. The result excludes the no-mixing hypothesis with a probability corresponding to 9.1 standard deviations and represents the first observation of D0-D̄0 oscillations from a single measurement. © 2013 CERN.
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Measurement of upsilon production in 7 TeV pp collisions at ATLAS

Physical Review D - Particles, Fields, Gravitation and Cosmology 87:5 (2013)

Authors:

G Aad, T Abajyan, B Abbott, J Abdallah, S Abdel Khalek, AA Abdelalim, O Abdinov, R Aben, B Abi, M Abolins, OS Abouzeid, H Abramowicz, H Abreu, BS Acharya, L Adamczyk, DL Adams, TN Addy, J Adelman, S Adomeit, P Adragna, T Adye, S Aefsky, JA Aguilar-Saavedra, M Agustoni, M Aharrouche, SP Ahlen, F Ahles, A Ahmad, M Ahsan, G Aielli, TPA Åkesson, G Akimoto, AV Akimov, MS Alam, MA Alam, J Albert, S Albrand, M Aleksa, IN Aleksandrov, F Alessandria, C Alexa, G Alexander, G Alexandre, T Alexopoulos, M Alhroob, M Aliev, G Alimonti, J Alison, BMM Allbrooke, PP Allport, SE Allwood-Spiers, J Almond, A Aloisio, R Alon, A Alonso, F Alonso, A Altheimer, B Alvarez Gonzalez, MG Alviggi, K Amako, C Amelung, VV Ammosov, SP Amor Dos Santos, A Amorim, N Amram, C Anastopoulos, LS Ancu, N Andari, T Andeen, CF Anders, G Anders, KJ Anderson, A Andreazza, V Andrei, ML Andrieux, XS Anduaga, S Angelidakis, P Anger, A Angerami, F Anghinolfi, A Anisenkov, N Anjos, A Annovi, A Antonaki, M Antonelli, A Antonov, J Antos, F Anulli, M Aoki, S Aoun, L Aperio Bella, R Apolle, G Arabidze, I Aracena, Y Arai, ATH Arce, S Arfaoui, JF Arguin, S Argyropoulos, E Arik

Abstract:

Using 1.8 fb-1 of pp collisions at a center-of-mass energy of 7 TeV recorded by the ATLAS detector at the Large Hadron Collider, we present measurements of the production cross sections of Υ(1S,2S,3S) mesons. Υ mesons are reconstructed using the dimuon decay mode. Total production cross sections for pT<70 GeV and in the rapidity interval |yΥ|<2.25 are measured to be, 8.01±0.02±0.36±0.31 nb, 2.05±0.01±0.12±0.08 nb, and 0.92±0.01±0. 07±0.04 nb, respectively, with uncertainties separated into statistical, systematic, and luminosity measurement effects. In addition, differential cross section times dimuon branching fractions for Υ(1S), Υ(2S), and Υ(3S) as a function of Υ transverse momentum pT and rapidity are presented. These cross sections are obtained assuming unpolarized production. If the production polarization is fully transverse or longitudinal with no azimuthal dependence in the helicity frame, the cross section may vary by approximately ±20%. If a nontrivial azimuthal dependence is considered, integrated cross sections may be significantly enhanced by a factor of 2 or more. We compare our results to several theoretical models of Υ meson production, finding that none provide an accurate description of our data over the full range of Υ transverse momenta accessible with this data set.
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