SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Johansson A. G. M.) "

Sökning: WFRF:(Johansson A. G. M.)

Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
61.
  • Aad, G., et al. (författare)
  • Search for the Higgs Boson in the H -> WW -> l nu jj Decay Channel in pp Collisions at root s=7 TeV with the ATLAS Detector
  • 2011
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 107:23
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for a Higgs boson has been performed in the H -> WW -> l nu jj channel in 1.04 fb(-1) of pp collision data at root s = 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. No significant excess of events is observed over the expected background and limits on the Higgs boson production cross section are derived for a Higgs boson mass in the range 240 GeV < m(H) < 600 GeV. The best sensitivity is reached for m(H) = 400 GeV, where the 95% confidence level upper bound on the cross section for H -> WW production is 3.1 pb, or 2.7 times the standard model prediction.
62.
  • Aad, G., et al. (författare)
  • Search for the Standard Model Higgs boson in the two photon decay channel with the ATLAS detector at the LHC
  • 2011
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 705:5, s. 452-470
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for the Standard Model Higgs boson in the two photon decay channel is reported, using 1.08 fb(-1) of proton-proton collision data at a centre-of-mass energy of 7 TeV recorded by the ATLAS detector. No significant excess is observed in the investigated mass range of 110-150 GeV. Upper limits on the cross-section,times branching ratio of between 2.0 and 5.8 times the Standard Model prediction are derived for this mass range. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved.
63.
  • Aad, G., et al. (författare)
  • Studies of the performance of the ATLAS detector using cosmic-ray muons
  • 2011
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 71:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Muons from cosmic-ray interactions in the atmosphere provide a high-statistics source of particles that can be used to study the performance and calibration of the ATLAS detector. Cosmic-ray muons can penetrate to the cavern and deposit energy in all detector subsystems. Such events have played an important role in the commissioning of the detector since the start of the installation phase in 2005 and were particularly important for understanding the detector performance in the time prior to the arrival of the first LHC beams. Global cosmic-ray runs were undertaken in both 2008 and 2009 and these data have been used through to the early phases of collision data-taking as a tool for calibration, alignment and detector monitoring. These large datasets have also been used for detector performance studies, including investigations that rely on the combined performance of different subsystems. This paper presents the results of performance studies related to combined tracking, lepton identification and the reconstruction of jets and missing transverse energy. Results are compared to expectations based on a cosmic-ray event generator and a full simulation of the detector response.
64.
  • Aad, G., et al. (författare)
  • ATLAS search for a heavy gauge boson decaying to a charged lepton and a neutrino in pp collisions at root s=7 TeV
  • 2012
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 72:12
  • Tidskriftsartikel (refereegranskat)abstract
    • The ATLAS detector at the LHC is used to search for high-mass states, such as heavy charged gauge bosons (W'), decaying to a charged lepton (electron or muon) and a neutrino. Results are presented based on the analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.7 fb(-1). No excess beyond Standard Model expectations is observed. A W' with Sequential Standard Model couplings is excluded at the 95 % credibility level for masses up to 2.55 TeV. Excited chiral bosons (W*) with equivalent coupling strength are excluded for masses up to 2.42 TeV.
65.
  • Aad, Georges, et al. (författare)
  • Electron performance measurements with the ATLAS detector using the 2010 LHC proton-proton collision data
  • 2012
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 72:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Detailed measurements of the electron performance of the ATLAS detector at the LHC are reported, using decays of the Z, W and J/psi particles. Data collected in 2010 at root s = 7 TeV are used, corresponding to an integrated luminosity of almost 40 pb(-1). The inter-alignment of the inner detector and the electromagnetic calorimeter, the determination of the electron energy scale and resolution, and the performance in terms of response uniformity and linearity are discussed. The electron identification, reconstruction and trigger efficiencies, as well as the charge misidentification probability, are also presented.
66.
  • Aad, G., et al. (författare)
  • Jet mass and substructure of inclusive jets in root s=7 TeV pp collisions with the ATLAS experiment
  • 2012
  • Ingår i: Journal of High Energy Physics. - Springer. - 1029-8479. ; :5
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent studies have highlighted the potential of jet substructure techniques to identify the hadronic decays of boosted heavy particles. These studies all rely upon the assumption that the internal substructure of jets generated by QCD radiation is well understood. In this article, this assumption is tested on an inclusive sample of jets recorded with the ATLAS detector in 2010, which corresponds to 35 pb(-1) of pp collisions delivered by the LHC at root s = 7 TeV. In a subsample of events with single pp collisions, measurements corrected for detector efficiency and resolution are presented with full systematic uncertainties. Jet invariant mass, k(t) splitting scales and N-subjettiness variables are presented for anti-k(t) R = 1.0 jets and Cambridge-Aachen R = 1.2 jets. Jet invariant-mass spectra for Cambridge-Aachen R = 1.2 jets after a splitting and filtering procedure are also presented. Leading-order parton-shower Monte Carlo predictions for these variables are found to be broadly in agreement with data. The dependence of mean jet mass on additional pp interactions is also explored.
67.
  • Aad, G., et al. (författare)
  • Measurement of t(t)over-bar production with a veto on additional central jet activity in pp collisions at root s=7 TeV using the ATLAS detector
  • 2012
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 72:6
  • Tidskriftsartikel (refereegranskat)abstract
    • A measurement of the jet activity in t (t) over bar events produced in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented, using 2.05 fb(-1) of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. The t (t) over bar events are selected in the dilepton decay channel with two identified b-jets from the top quark decays. Events are vetoed if they contain an additional jet with transverse momentum above a threshold in a central rapidity interval. The fraction of events surviving the jet veto is presented as a function of this threshold for four different central rapidity interval definitions. An alternate measurement is also performed, in which events are vetoed if the scalar transverse momentum sum of the additional jets in each rapidity interval is above a threshold. In both measurements, the data are corrected for detector effects and compared to the theoretical models implemented in MC@NLO, POWHEG, ALPGEN and SHERPA. The experimental uncertainties are often smaller than the spread of theoretical predictions, allowing deviations between data and theory to be observed in some regions of phase space.
68.
  • Aad, G., et al. (författare)
  • Measurement of the azimuthal anisotropy for charged particle production in root s(NN)=2.76 TeV lead-lead collisions with the ATLAS detector
  • 2012
  • Ingår i: Physical Review C (Nuclear Physics). - American Physical Society. - 0556-2813. ; 86:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Differential measurements of charged particle azimuthal anisotropy are presented for lead-lead collisions at root sNN = 2.76 TeV with the ATLAS detector at the LHC, based on an integrated luminosity of approximately 8 mu b(-1). This anisotropy is characterized via a Fourier expansion of the distribution of charged particles in azimuthal angle relative to the reaction plane, with the coefficients v(n) denoting the magnitude of the anisotropy. Significant v(2)-v(6) values are obtained as a function of transverse momentum (0.5 < p(T) < 20 GeV), pseudorapidity (|eta| < 2.5), and centrality using an event plane method. The v(n) values for n >= 3 are found to vary weakly with both eta and centrality, and their p(T) dependencies are found to follow an approximate scaling relation, v(n)(1/n)(p(T)) proportional to v(2)(1/2)(p(T)), except in the top 5% most central collisions. A Fourier analysis of the charged particle pair distribution in relative azimuthal angle (Delta phi = phi(a)-phi(b)) is performed to extract the coefficients v(n,n) = < cos n Delta phi >. For pairs of charged particles with a large pseudorapidity gap (|Delta eta = eta(a) - eta(b)| > 2) and one particle with p(T) < 3 GeV, the v(2,2)-v(6,6) values are found to factorize as v(n,n)(p(T)(a), p(T)(b)) approximate to v(n) (p(T)(a))v(n)(p(T)(b)) in central and midcentral events. Such factorization suggests that these values of v(2,2)-v(6,6) are primarily attributable to the response of the created matter to the fluctuations in the geometry of the initial state. A detailed study shows that the v(1,1)(p(T)(a), p(T)(b)) data are consistent with the combined contributions from a rapidity-even v(1) and global momentum conservation. A two-component fit is used to extract the v(1) contribution. The extracted v(1) isobserved to cross zero at pT approximate to 1.0 GeV, reaches a maximum at 4-5 GeV with a value comparable to that for v(3), and decreases at higher p(T).
69.
  • Aad, G., et al. (författare)
  • Measurement of the azimuthal ordering of charged hadrons with the ATLAS detector
  • 2012
  • Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - American Physical Society. - 1550-2368. ; 86:5
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents a study of the possible ordering of charged hadrons in the azimuthal angle relative to the beam axis in high-energy proton-proton collisions at the Large Hadron Collider (LHC). A spectral analysis of correlations between longitudinal and transverse components of the momentum of the charged hadrons, driven by the search for phenomena related to the structure of the QCD field, is performed. Data were recorded with the ATLAS detector at center-of-mass energies of root s = 900 GeV and root s = 7 TeV. The correlations measured in a kinematic region dominated by low-p(T) particles are not well described by conventional models of hadron production. The measured spectra show features consistent with the fragmentation of a QCD string represented by a helixlike ordered gluon chain.
70.
  • Aad, G., et al. (författare)
  • Measurement of the centrality dependence of the charged particle pseudorapidity distribution in lead-lead collisions at root s(NN)=2.76 TeV with the ATLAS detector
  • 2012
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 710:3, s. 363-382
  • Tidskriftsartikel (refereegranskat)abstract
    • The ATLAS experiment at the LHC has measured the centrality dependence of charged particle pseudorapidity distributions over vertical bar eta vertical bar < 2 in lead-lead collisions at a nucleon-nucleon centre-of-mass energy of root s(NN) = 2.76 TeV. In order to include particles with transverse momentum as low as 30 MeV, the data were recorded with the central solenoid magnet off. Charged particles were reconstructed with two algorithms (2-point "tracklets" and full tracks) using information from the pixel detector only. The lead-lead collision centrality was characterized by the total transverse energy in the forward calorimeter in the range 3.2 < vertical bar eta vertical bar< 4.9. Measurements are presented of the per-event charged particle pseudorapidity distribution, dN(ch)/d eta, and the average charged particle multiplicity in the pseudorapidity interval vertical bar eta vertical bar < 0.5 in several intervals of collision centrality. The results are compared to previous mid-rapidity measurements at the LHC and RHIC. The variation of the mid-rapidity charged particle yield per colliding nucleon pair with the number of participants is consistent with lower root s(NN) results. The shape of the dN(ch)/d eta distribution is found to be independent of centrality within the systematic uncertainties of the measurement. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
Skapa referenser, mejla, bekava och länka
Åtkomst
fritt online (550)
Typ av publikation
tidskriftsartikel (1378)
konferensbidrag (92)
forskningsöversikt (7)
bokkapitel (5)
annan publikation (2)
rapport (2)
visa fler...
patent (2)
proceedings (redaktörskap) (1)
visa färre...
Typ av innehåll
refereegranskat (1414)
övrigt vetenskapligt (76)
populärvet., debatt m.m. (6)
Författare/redaktör
Andreazza, A. (451)
Abdallah, J, (449)
Anjos, N. (443)
Baroncelli, A. (441)
Asman, B. (435)
Allport, P. P. (405)
visa fler...
Åsman, Barbro, (397)
Bai, Y. (395)
Moa, Torbjörn, (382)
Baker, O. K. (380)
Aleksa, M. (379)
Arabidze, G. (379)
Beck, H. P. (379)
Adye, T. (378)
Anghinolfi, F. (378)
Antonaki, A. (377)
Bates, R. L. (377)
Jon-And, Kerstin, (376)
Antonelli, M. (376)
Adelman, J. (375)
Asquith, L. (375)
Banas, E. (375)
Barklow, T. (375)
Barr, A. J. (375)
Bohm, Christian, (374)
Sjölin, Jörgen, (374)
Gellerstedt, Karl, (374)
Artamonov, A., (374)
Eriksson, Daniel, (374)
Abi, B. (374)
Abramowicz, H. (374)
Akimov, A. V. (374)
Aleksandrov, I. N. (374)
Alexandre, G. (374)
Alhroob, M. (374)
Amelung, C. (374)
Anastopoulos, C. (374)
Arai, Y. (374)
Arnaez, O. (374)
Assamagan, K. (374)
Azuma, Y. (374)
Baak, M. A. (374)
Bachacou, H. (374)
Bachas, K. (374)
Backes, M. (374)
Barisonzi, M. (374)
Barlow, N. (374)
Batley, J. R. (374)
Beau, T. (374)
Bell, W. H. (374)
visa färre...
Lärosäte
Uppsala universitet (866)
Lunds universitet (649)
Stockholms universitet (481)
Kungliga Tekniska Högskolan (425)
Karolinska Institutet (253)
Umeå universitet (133)
visa fler...
Göteborgs universitet (119)
Chalmers tekniska högskola (89)
Linköpings universitet (41)
Linnéuniversitetet (31)
Örebro universitet (12)
RISE (7)
Högskolan Dalarna (6)
Högskolan i Jönköping (3)
Högskolan Väst (2)
Mälardalens högskola (2)
Mittuniversitetet (2)
Försvarshögskolan (2)
Karlstads universitet (2)
Luleå tekniska universitet (1)
Högskolan Kristianstad (1)
Södertörns högskola (1)
Högskolan i Gävle (1)
Naturhistoriska riksmuseet (1)
Röda Korsets Högskola (1)
visa färre...
Språk
Engelska (1479)
Svenska (3)
Odefinierat språk (3)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (977)
Medicin och hälsovetenskap (312)
Teknik (39)
Samhällsvetenskap (19)
Lantbruksvetenskap (2)

År

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy