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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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Search for new physics in events with same-sign dileptons and jets in pp collisions at √s = 8 TeV

Journal of High Energy Physics 2014:1 (2014)

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, 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, J Suarez Gonzalez, S Alderweireldt, M Bansal, S Bansal, T Cornelis, EA De Wolf, X Janssen, A Knutsson, S Luyckx, L Mucibello, S Ochesanu, B Roland, R Rougny, H Van Haevermaet, P Van Mechelen, N Van Remortel, A Van Spilbeeck, F Blekman, S Blyweert, J D'hondt, N Heracleous, A Kalogeropoulos, J Keaveney, TJ Kim, S Lowette, M Maes, A Olbrechts, D Strom, S Tavernier, W Van Doninck, P Van Mulders, GP Van Onsem, I Villella, C Caillol, B Clerbaux, G De Lentdecker, L Favart, APR Gay, T Hreus, A Léonard, PE Marage, A Mohammadi, L Perniè, T Reis, T Seva, L Thomas, C Vander Velde, P Vanlaer, J Wang, V Adler, K Beernaert, L Benucci, A Cimmino, S Costantini, S Dildick, G Garcia, B Klein, J Lellouch, J Mccartin, AA Ocampo Rios, D Ryckbosch, M Sigamani, N Strobbe, F Thyssen, M Tytgat, S Walsh, E Yazgan

Abstract:

A search for new physics is performed based on events with jets and a pair of isolated, same-sign leptons. The results are obtained using a sample of proton-proton collision data collected by the CMS experiment at a centre-of-mass energy of 8 TeV at the LHC, corresponding to an integrated luminosity of 19.5 fb-1. In order to be sensitive to a wide variety of possible signals beyond the standard model, multiple search regions defined by the missing transverse energy, the hadronic energy, the number of jets and b-quark jets, and the transverse momenta of the leptons in the events are considered. No excess above the standard model background expectation is observed and constraints are set on a number of models for new physics, as well as on the same-sign top-quark pair and quadruple-top-quark production cross sections. Information on event selection efficiencies is also provided, so that the results can be used to confront an even broader class of new physics models. [Figure not available: see fulltext.] © 2014 The Author(s).
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Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using s=8 TeV proton-proton collision data

Journal of High Energy Physics 2014:9 (2014)

Authors:

ATLAS collaboration The, G Aad, B Abbott, J Abdallah, SA 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, MJA 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, BA Gonzalez, MG Alviggi, MG Alviggi, K Amako, YA Coutinho, C Amelung, D Amidei, SPAD Santos, SPAD 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: A search for squarks and gluinos in final states containing high-pT jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in (formula presented) TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A0 = −2m0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector.[Figure not available: see fulltext.]
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