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Measurement of differential production cross-sections for a Z boson in association with b-jets in 7 TeV proton-proton collisions with the ATLAS detector

Journal of High Energy Physics 2014:10 (2014)

Authors:

G Aad, B Abbott, J Abdallah, S Abdel Khalek, O Abdinov, R Aben, B Abi, M Abolins, OS AbouZeid, H Abramowicz, H Abreu, R Abreu, Y Abulaiti, Y Abulaiti, BS Acharya, BS Acharya, BS Acharya, L Adamczyk, DL Adams, J Adelman, S Adomeit, T Adye, T Agatonovic-Jovin, JA Aguilar-Saavedra, JA Aguilar-Saavedra, M Agustoni, SP Ahlen, F Ahmadov, F Ahmadov, G Aielli, G Aielli, H Akerstedt, H Akerstedt, TPA Åkesson, G Akimoto, AV Akimov, GL Alberghi, GL Alberghi, J Albert, S Albrand, MJ Alconada Verzini, M Aleksa, IN Aleksandrov, C Alexa, G Alexander, G Alexandre, T Alexopoulos, M Alhroob, M Alhroob, G Alimonti, L Alio, J Alison, BMM Allbrooke, LJ Allison, PP Allport, J Almond, A Aloisio, A Aloisio, A Alonso, F Alonso, C Alpigiani, A Altheimer, B Alvarez Gonzalez, MG Alviggi, MG Alviggi, K Amako, Y Amaral Coutinho, C Amelung, D Amidei, SP Amor Dos Santos, SP Amor Dos Santos, A Amorim, A Amorim, S Amoroso, N Amram, G Amundsen, C Anastopoulos, LS Ancu, N Andari, T Andeen, CF Anders, G Anders, KJ Anderson, A Andreazza, A Andreazza, V Andrei, XS Anduaga, S Angelidakis, I Angelozzi, P Anger, A Angerami, F Anghinolfi, AV Anisenkov, N Anjos, A Annovi, A Antonaki, M Antonelli, A Antonov, J Antos, F Anulli

Abstract:

© 2014, CERN. Measurements of differential production cross-sections of a Z boson in association with b-jets in pp collisions at √s = 7 TeV are reported. The data analysed correspond to an integrated luminosity of 4.6 fb-1 recorded with the ATLAS detector at the Large Hadron Collider. Particle-level cross-sections are determined for events with a Z boson decaying into an electron or muon pair, and containing b-jets. For events with at least one b-jet, the cross-section is presented as a function of the Z boson transverse momentum and rapidity, together with the inclusive b-jet cross-section as a function of b-jet transverse momentum, rapidity and angular separations between the b-jet and the Z boson. For events with at least two b-jets, the cross-section is determined as a function of the invariant mass and angular separation of the two highest transverse momentum b-jets, and as a function of the Z boson transverse momentum and rapidity. Results are compared to leading-order and next-to-leading-order perturbative QCD calculations.
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Measurement of prompt J/ψ pair production in pp collisions at√s = 7 Tev

Social Psychiatry and Psychiatric Epidemiology 2014:9 (2014)

Authors:

CMS collaboration The, V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, C Hartl, N Hörmann, J Hrubec, M Jeitler, W Kiesenhofer, V Knünz, M Krammer, I Krätschmer, D Liko, I Mikulec, D Rabady, B Rahbaran, H Rohringer, R Schöfbeck, J Strauss, A Taurok, W Treberer-Treberspurg, W Waltenberger, CE Wulz, V Mossolov, N Shumeiko, JS Gonzalez, S Alderweireldt, M Bansal, S Bansal, T Cornelis, EA De Wolf, X Janssen, A Knutsson, S Luyckx, S Ochesanu, B Roland, R Rougny, M Van De Klundert, H Van Haevermaet, P Van Mechelen, N Van Remortel, A Van Spilbeeck, F Blekman, S Blyweert, J D Hondt, N Daci, N Heracleous, J Keaveney, TJ Kim, S Lowette, M Maes, A Olbrechts, Q Python, D Strom, S Tavernier, W Van Doninck, P Van Mulders, GP Van Onsem, I Villella, C Caillol, B Clerbaux, G De Lentdecker, D Dobur, L Favart, APR Gay, A Grebenyuk, A Léonard, A Mohammadi, L Perniè, T Reis, T Seva, L Thomas, CV Velde, P Vanlaer, J Wang, V Adler, K Beernaert, L Benucci, A Cimmino, S Costantini, S Crucy, S Dildick, A Fagot, G Garcia, J Mccartin

Abstract:

© 2014, The Author(s).Abstract: Production of prompt J/ψ meson pairs in proton-proton collisions at (formula presented.) = 7 TeV is measured with the CMS experiment at the LHC in a data sample corresponding to an integrated luminosity of about 4.7 fb−1. The two J/ψ mesons are fully reconstructed via their decays into μ+μ− pairs. This observation provides for the first time access to the high-transverse-momentum region of J/ψ pair production where model predictions are not yet established. The total and differential cross sections are measured in a phase space defined by the individual J/ψ transverse momentum (pTJ/ψ) and rapidity (|yJ/ψ|): |yJ/ψ | < 1.2 for pTJ/ψ > 6.5 GeV/c; 1.2 < |yJ/ψ| < 1.43 for a pT threshold that scales linearly with |yJ/ψ| from 6.5 to 4.5 GeV/c; and 1.43 < |yJ/ψ| < 2.2 for pTJ/ψ > 4.5 GeV/c. The total cross section, assuming unpolarized prompt J/ψ pair production is 1.49 ± 0.07 (stat) ±0.13 (syst) nb. Different assumptions about the J/ψ polarization imply modifications to the cross section ranging from −31% to +27%.
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Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at S=8 TeV with ATLAS

Journal of High Energy Physics 2014:9 (2014) 1-61

Authors:

ATLAS collaboration The, G Aad, B Abbott, J Abdallah, S Abdel Khalek, O Abdinov, R Aben, B Abi, M Abolins, OS AbouZeid, H Abramowicz, H Abreu, R Abreu, Y Abulaiti, Y Abulaiti, BS Acharya, BS Acharya, BS Acharya, L Adamczyk, DL Adams, J Adelman, S Adomeit, T Adye, T Agatonovic-Jovin, JA Aguilar-Saavedra, JA Aguilar-Saavedra, M Agustoni, SP Ahlen, F Ahmadov, F Ahmadov, G Aielli, G Aielli, H Akerstedt, H Akerstedt, TPA Åkesson, G Akimoto, AV Akimov, GL Alberghi, GL Alberghi, J Albert, S Albrand, MJ Alconada Verzini, M Aleksa, IN Aleksandrov, C Alexa, G Alexander, G Alexandre, T Alexopoulos, M Alhroob, M Alhroob, G Alimonti, L Alio, J Alison, BMM Allbrooke, LJ Allison, PP Allport, J Almond, A Aloisio, A Aloisio, A Alonso, F Alonso, C Alpigiani, A Altheimer, B Alvarez Gonzalez, MG Alviggi, MG Alviggi, K Amako, Y Amaral Coutinho, C Amelung, D Amidei, SP Amor Dos Santos, SP Amor Dos Santos, A Amorim, A Amorim, S Amoroso, N Amram, G Amundsen, C Anastopoulos, LS Ancu, N Andari, T Andeen, CF Anders, G Anders, KJ Anderson, A Andreazza, A Andreazza, V Andrei, XS Anduaga, S Angelidakis, I Angelozzi, P Anger, A Angerami, F Anghinolfi, AV Anisenkov, N Anjos, A Annovi, A Antonaki, M Antonelli, A Antonov, J Antos

Abstract:

© 2014, The Author(s). Abstract: Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of (formula presented) TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations.[Figure not available: see fulltext.]
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Morphological classification of radio sources for galaxy evolution and cosmology with the SKA

Proceedings of Science 9-13-June-2014 (2014)

Authors:

S Makhathini, OM Smirnov, MJ Jarvis, I Heywood

Abstract:

Morphologically classifying radio sources in continuum images with the SKA has the potential to address some of the key questions in cosmology and galaxy evolution. In particular, we may use different classes of radio sources as independent tracers of the dark-matter density field, and thus overcome cosmic variance in measuring large-scale structure, while on the galaxy evolution side we could measure the mechanical feedback from FRII and FRI jets. This work makes use of a MeqTrees-based simulations framework to forecast the ability of the SKA to recover true source morphologies at high redshifts. A suite of high resolution images containing realistic continuum source distributions with different morphologies (FRI, FRII, starburst galaxies) is fed through an SKA Phase 1 simulator, then analysed to determine the sensitivity limits at which the morphologies can still be distinguished. We also explore how changing the antenna distribution affects these results.
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Overview of complementarity and synergy with other wavelengths in cosmology in the SKA era

Proceedings of Science 9-13-June-2014 (2014)

Authors:

K Takahashi, ML Brown, C Burigana, CA Jackson, M Jarvis, TD Kitching, JP Kneib, M Oguri, S Prunet, H Shan, JL Starck, D Yamauchi

Abstract:

We give an overview of complementarity and synergy in cosmology between the Square Kilometre Array and future survey projects in other wavelengths. In the SKA era, precision cosmology will be limited by systematic errors and cosmic variance, rather than statistical errors. However, combining and/or cross-correlating multi-wavelength data, from the SKA to the cosmic microwave background, optical/infrared and X-ray, substantially reduce these limiting factors. In this chapter, we summarize future survey projects and show highlights of complementarity and synergy, which can be very powerful to probe major cosmological problems such as dark energy, modified gravity and primordial non-Gaussianity.
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