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Diffractive dijet production in p̄p collisions at √s=1.96TeV

Physical Review D - Particles, Fields, Gravitation and Cosmology 86:3 (2012)

Authors:

T Aaltonen, M Albrow, 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 report on a study of diffractive dijet production in p̄p collisions at √s=1.96TeV using the CDF II detector at the Fermilab Tevatron p̄p collider. A data sample from 310pb -1 of integrated luminosity collected by triggering on a high transverse energy jet, ETjet, in coincidence with a recoil antiproton detected in a Roman pot spectrometer is used to measure the ratio of single-diffractive to inclusive-dijet event rates as a function of xp ̄ of the interacting parton in the antiproton, the Bjorken-x, xBjp̄, and a Q2(ETjet)2 in the ranges 10 -3-4GeV2. The t p̄ dependence is measured as a function of Q2 and xBjp̄ and compared with that of inclusive single diffraction dissociation. We find weak xBjp̄ and Q2 dependencies in the ratio of single diffractive to inclusive event rates, and no significant Q2 dependence in the diffractive t p̄ distributions. © 2012 American Physical Society.
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Search for pair production of a new b′ quark that decays into a Z boson and a bottom quark with the ATLAS detector

Physical Review Letters 109:7 (2012)

Authors:

G Aad, B Abbott, J Abdallah, S Abdel Khalek, AA Abdelalim, A Abdesselam, O Abdinov, B Abi, M Abolins, OS Abouzeid, H Abramowicz, H Abreu, E Acerbi, BS Acharya, L Adamczyk, DL Adams, TN Addy, J Adelman, M Aderholz, S Adomeit, P Adragna, T Adye, S Aefsky, JA Aguilar-Saavedra, M Aharrouche, SP Ahlen, F Ahles, A Ahmad, M Ahsan, G Aielli, T Akdogan, TPA Åkesson, G Akimoto, AV Akimov, A Akiyama, 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, M Aliyev, BMM Allbrooke, PP Allport, SE Allwood-Spiers, J Almond, A Aloisio, R Alon, A Alonso, B Alvarez Gonzalez, MG Alviggi, K Amako, P Amaral, C Amelung, VV Ammosov, A Amorim, G Amorós, N Amram, C Anastopoulos, LS Ancu, N Andari, T Andeen, CF Anders, G Anders, KJ Anderson, A Andreazza, V Andrei, ML Andrieux, XS Anduaga, A Angerami, F Anghinolfi, A Anisenkov, N Anjos, A Annovi, A Antonaki, M Antonelli, A Antonov, J Antos, F Anulli, S Aoun, L Aperio Bella, R Apolle, G Arabidze, I Aracena, Y Arai, ATH Arce, S Arfaoui, JF Arguin, E Arik, M Arik, AJ Armbruster

Abstract:

A search is reported for the pair production of a new quark b′ with at least one b′ decaying to a Z boson and a bottom quark. The data, corresponding to 2.0fb-1 of integrated luminosity, were collected from pp collisions at √s=7TeV with the ATLAS detector at the CERN Large Hadron Collider. Using events with a b-tagged jet and a Z boson reconstructed from opposite-charge electrons, the mass distribution of large transverse momentum b′ candidates is tested for an enhancement. No evidence for a b′ signal is detected in the observed mass distribution, resulting in the exclusion at a 95% confidence level of b′ quarks with masses m b′<400GeV that decay entirely via b′→Z+b. In the case of a vectorlike singlet b′ mixing solely with the third standard model generation, masses mb′<358GeV are excluded. © 2012 CERN.
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Study of the dijet mass spectrum in pp to W + jets events at sqrt(s) = 7 TeV

ArXiv 1208.3477 (2012)
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Measurement of the Λb cross section and the Λ-b to Λb ratio with J/ψΛ decays in pp collisions at s=7 TeV

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 714:2-5 (2012) 136-157

Authors:

S Chatrchyan, V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, J Hammer, N Hörmann, J Hrubec, M Jeitler, W Kiesenhofer, V Knünz, M Krammer, D Liko, I Mikulec, M Pernicka, B Rahbaran, C Rohringer, H Rohringer, R Schöfbeck, J Strauss, A Taurok, P Wagner, W Waltenberger, G Walzel, E Widl, CE Wulz, V Mossolov, N Shumeiko, J Suarez Gonzalez, S Bansal, T Cornelis, EA De Wolf, X Janssen, S Luyckx, T Maes, L Mucibello, S Ochesanu, B Roland, R Rougny, M Selvaggi, Z Staykova, H Van Haevermaet, P Van Mechelen, N Van Remortel, A Van Spilbeeck, F Blekman, S Blyweert, J D'Hondt, R Gonzalez Suarez, A Kalogeropoulos, M Maes, A Olbrechts, W Van Doninck, P Van Mulders, GP Van Onsem, I Villella, O Charaf, B Clerbaux, G De Lentdecker, V Dero, APR Gay, T Hreus, A Léonard, PE Marage, T Reis, L Thomas, C Vander Velde, P Vanlaer, J Wang, V Adler, K Beernaert, A Cimmino, S Costantini, G Garcia, M Grunewald, B Klein, J Lellouch, A Marinov, J Mccartin, AA Ocampo Rios, D Ryckbosch, N Strobbe, F Thyssen, M Tytgat, L Vanelderen, P Verwilligen, S Walsh, E Yazgan, N Zaganidis, S Basegmez, G Bruno, R Castello, L Ceard

Abstract:

The Λb differential production cross section and the cross section ratio σ(Λ-b)/σ(Λb) are measured as functions of transverse momentum pTΛb and rapidity |yΛb| in pp collisions at s=7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Λb decays reconstructed in the exclusive final state J/ψΛ, with the subsequent decays J/ψ→μ+μ- and Λ→pπ, using a data sample corresponding to an integrated luminosity of 1.9 fb-1. The product σ(Λb)×B(Λb→J/ψΛ) versus pTΛb falls faster than that of b mesons. The measured value of σ(Λb)×B(Λb→J/ψΛ) for pTΛb>10 GeV and |yΛb|<2.0 is 1.16±0.06±0.12nb, and the integrated σ(Λ-b)/σ(Λb) ratio is 1.02±0.07±0.09, where the uncertainties are statistical and systematic, respectively. © 2012 CERN.
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Observation of sequential Upsilon suppression in PbPb collisions

ArXiv 1208.2826 (2012)
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