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1.	Aad, G., et al. (författare) 2011 Tidskriftsartikel (refereegranskat)
2.	Aad, G., et al. (författare) 2012 Tidskriftsartikel (refereegranskat)
3.	Aad, G., et al. (författare) 2011 Tidskriftsartikel (refereegranskat)
4.	Aad, G., et al. (författare) 2012 Tidskriftsartikel (refereegranskat)
5.	Aad, G., et al. (författare) 2012 Tidskriftsartikel (refereegranskat)
6.	Aad, G., et al. (författare) 2012 Tidskriftsartikel (refereegranskat)
7.	Aad, G., et al. (författare) 2012 Tidskriftsartikel (refereegranskat)
8.	Aad, G., et al. (författare) 2011 Tidskriftsartikel (refereegranskat)
9.	Aad, G., et al. (författare) 2013 Ingår i: The European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6052. ; 73:3 Tidskriftsartikel (refereegranskat)
10.	Aad, G., et al. (författare) Drift Time Measurement in the ATLAS Liquid Argon Electromagnetic Calorimeter using Cosmic Muons 2010 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 755-785 Tidskriftsartikel (refereegranskat)
11.	Aad, G., et al. (författare) Readiness of the ATLAS liquid argon calorimeter for LHC collisions 2010 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 723-753 Tidskriftsartikel (refereegranskat)
12.	Aad, G., et al. (författare) Evidence for the spin-0 nature of the Higgs boson using ATLAS data 2013 Tidskriftsartikel (refereegranskat)
13.	Aad, G., et al. (författare) 2014 Tidskriftsartikel (refereegranskat)
14.	Aad, G., et al. (författare) 2014 Ingår i: The European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6052. ; 74:8 Tidskriftsartikel (refereegranskat)
15.	Aad, G., et al. (författare) The ATLAS Simulation Infrastructure 2010 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 823-874 Tidskriftsartikel (refereegranskat)abstract The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate particle collisions, through packages simulating the response of the various detectors and triggers. All of these components come together under the ATLAS simulation infrastructure. In this paper, that infrastructure is discussed, including that supporting the detector description, interfacing the event generation, and combining the GEANT4 simulation of the response of the individual detectors. Also described are the tools allowing the software validation, performance testing, and the validation of the simulated output against known physics processes.
16.	Aad, G., et al. (författare) Readiness of the ATLAS Tile Calorimeter for LHC collisions 2010 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:4, s. 1193-1236 Tidskriftsartikel (refereegranskat)abstract The Tile hadronic calorimeter of the ATLAS detector has undergone extensive testing in the experimental hall since its installation in late 2005. The readout, control and calibration systems have been fully operational since 2007 and the detector has successfully collected data from the LHC single beams in 2008 and first collisions in 2009. This paper gives an overview of the Tile Calorimeter performance as measured using random triggers, calibration data, data from cosmic ray muons and single beam data. The detector operation status, noise characteristics and performance of the calibration systems are presented, as well as the validation of the timing and energy calibration carried out with minimum ionising cosmic ray muons data. The calibration systems' precision is well below the design value of 1%. The determination of the global energy scale was performed with an uncertainty of 4%.
17.	Aad, G., et al. (författare) The ATLAS Inner Detector commissioning and calibration 2010 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 787-821 Tidskriftsartikel (refereegranskat)abstract The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7.6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes, specific energy-loss calibration and transition radiation turn-on measurements have been performed. Different alignment techniques have been used to reconstruct the detector geometry. After the initial alignment, a transverse impact parameter resolution of 22.1 +/- 0.9 mu m and a relative momentum resolution sigma (p) /p=(4.83 +/- 0.16)x10(-4) GeV(-1)xp (T) have been measured for high momentum tracks.
18.	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 Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 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.
19.	Aad, G., et al. (författare) Commissioning of the ATLAS Muon Spectrometer with cosmic rays 2010 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 875-916 Tidskriftsartikel (refereegranskat)abstract The ATLAS detector at the Large Hadron Collider has collected several hundred million cosmic ray events during 2008 and 2009. These data were used to commission the Muon Spectrometer and to study the performance of the trigger and tracking chambers, their alignment, the detector control system, the data acquisition and the analysis programs. We present the performance in the relevant parameters that determine the quality of the muon measurement. We discuss the single element efficiency, resolution and noise rates, the calibration method of the detector response and of the alignment system, the track reconstruction efficiency and the momentum measurement. The results show that the detector is close to the design performance and that the Muon Spectrometer is ready to detect muons produced in high energy proton-proton collisions.
20.	Schael, S., et al. (författare) Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP 2013 Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244 Forskningsöversikt (refereegranskat)abstract Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
21.	Abelev, B., et al. (författare) Measurement of inelastic, single- and double-diffraction cross sections in proton-proton collisions at the LHC with ALICE 2013 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 73:6 Tidskriftsartikel (refereegranskat)abstract Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass M-X < 200 GeV/c(2)) sigma(SD)/sigma(INEL) = 0.21 +/- 0.03, 0.20(-0.08)(+0.07,) and 0.20(-0.07)(+0.04), respectively at centre-of-mass energies root s = 0.9, 2.76, and 7 TeV; for double diffraction (for a pseudorapidity gap Delta eta > 3) sigma(DD)/sigma(INEL) = 0.11 +/- 0.03, 0.12 +/- 0.05, and 0.12(-0.04)(+0.05), respectively at root s = 0.9, 2.76, and 7 TeV. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: sigma(INEL) = 62.8(-4.0)(+2.4)(model) +/- 1.2(lumi) mb at root s = 2.76 TeV and 73.2(-4.6)(+2.0)(model) +/- 2.6(lumi) mb at root s = 7 TeV. The single- and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton-antiproton and proton-proton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.
22.	Abelev, B., et al. (författare) Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at root s(NN)=2.76 TeV 2013 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 720:1-3, s. 52-62 Tidskriftsartikel (refereegranskat)abstract The inclusive transverse momentum (p(T)) distributions of primary charged particles are measured in the pseudo-rapidity range vertical bar eta vertical bar <0.8 as a function of event centrality in Pb-Pb collisions at root S-NN = 2.76 TeV with ALICE at the LHC. The data are presented in the p(T) range 0.15 < p(T) <50 GeV/c for nine centrality intervals from 70-80% to 0-5%. The results in Pb-Pb are presented in terms of the nuclear modification factor R-AA using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-p(T) particles strongly depends on event centrality. The yield is most suppressed in central collisions (0-5%) with R-AA approximate to 0.13 at p(T) = 6-7 GeV/c. Above p(T) = 7 GeV/c, there is a significant rise in the nuclear modification factor, which reaches R-AA approximate to 0.4 for p(T) > 30 GeV/c. In peripheral collisions (70-80%), only moderate suppression (R-AA approximate to 0.6-0.7) and a weak p(T) dependence is observed. The measured nuclear modification factors are compared to other measurements and model calculations. (C) 2013 CERN. Published by Elsevier B.V. All rights reserved.
23.	Abelev, B., et al. (författare) Coherent J/psi photoproduction in ultra-peripheral Pb-Pb collisions at root s(NN)=2.76 TeV 2013 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 718:4-5, s. 1273-1283 Tidskriftsartikel (refereegranskat)abstract The ALICE Collaboration has made the first measurement at the LHC of J/psi photoproduction in ultra-peripheral Pb-Pb collisions at root s(NN) = 2.76 TeV. The J/psi is identified via its dimuon decay in the forward rapidity region with the muon spectrometer for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 55 mu b(-1). The cross section for coherent J/psi production in the rapidity interval -3.6 < y < -2.6 is measured to be d sigma(coh)(J/psi)/dy = 1.00 +/- 0.18(stat)(-0.26)(+0.24)(syst) mb. The result is compared to theoretical models for coherent J/psi production and found to be in good agreement with those models which include nuclear gluon shadowing. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
24.	Abelev, B., et al. (författare) D-S(+) meson production at central rapidity in proton-proton collisions at root s=7 TeV 2012 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 718:2, s. 279-294 Tidskriftsartikel (refereegranskat)abstract The P-T-differential inclusive production cross section of the prompt charm-strange meson D-s(+) in the rapidity range vertical bar y vertical bar < 0.5 was measured in proton-proton collisions at root s = 7 TeV at the LHC using the ALICE detector. The analysis was performed on a data sample of 2.98 x 10(8) events collected with a minimum-bias trigger. The corresponding integrated luminosity is L-int = 4.8 nb(-1). Reconstructing the decay D-s(+) -> phi pi(+) with phi -> K-K+, and its charge conjugate, about 480 D-s(+/-) mesons were counted, after selection cuts, in the transverse momentum range 2 < P-T < 12 GeV/c. The results are compared with predictions from models based on perturbative QCD. The ratios of the cross sections of four D meson species (namely D-0, D+, D*+ and D-s(+)) were determined both as a function of p(T) and integrated over p(T)after extrapolating to full p(T) range, together with the strangeness suppression factor in charm fragmentation. The obtained values are found to be compatible within uncertainties with those measured by other experiments in e(+)e(-), ep and pp interactions at various centre-of-mass energies. (C) 2012 CERN. Published by Elsevier By. All rights reserved.
25.	Abelev, B., et al. (författare) Measurement of electrons from beauty hadron decays in pp collisions at root s=7 TeV 2013 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 721:1-3, s. 13-23 Tidskriftsartikel (refereegranskat)abstract The production cross section of electrons from semileptonic decays of beauty hadrons was measured at mid-rapidity (vertical bar y vertical bar < 0.8) in, the transverse momentum range 1 < p(T) < 8 GeV/c with the ALICE experiment at the CERN LHC in pp collisions at a center of mass energy root s = 7 TeV using an integrated luminosity of 2.2 nb(-1). Electrons from beauty hadron decays were selected based on the displacement of the decay vertex from the collision vertex. A perturbative QCD calculation agrees with the measurement within uncertainties. The data were extrapolated to the full phase space to determine the total cross section for the production of beauty quark-antiquark pairs. (C) 2013 CERN. Published by Elsevier B.V. All rights reserved.
26.	Abelev, B., et al. (författare) Pion, Kaon, and Proton Production in Central Pb-Pb Collisions at root s(NN)=2.76 TeV 2012 Ingår i: Physical Review Letters. - 1079-7114. ; 109:25 Tidskriftsartikel (refereegranskat)abstract In this Letter we report the first results on pi(+/-), K-+/-, p, and (p) over bar production at midrapidity (vertical bar y vertical bar < 0.5) in central Pb-Pb collisions at root s(NN) = 2.76 TeV, measured by the ALICE experiment at the LHC. The p(T) distributions and yields are compared to previous results at root s(NN) = 200 GeV and expectations from hydrodynamic and thermal models. The spectral shapes indicate a strong increase of the radial flow velocity with root s(NN), which in hydrodynamic models is expected as a consequence of the increasing particle density. While the K/pi ratio is in line with predictions from the thermal model, the p/pi ratio is found to be lower by a factor of about 1.5. This deviation from thermal model expectations is still to be understood.
27.	Abelev, B., et al. (författare) Measurement of electrons from semileptonic heavy-flavor hadron decays in pp collisions at root s=7 TeV 2012 Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 86:11 Tidskriftsartikel (refereegranskat)abstract The differential production cross section of electrons from semileptonic heavy-flavor hadron decays has been measured at midrapidity (\y\ < 0.5) in proton-proton collisions at root s = 7 TeV with ALICE at the LHC. Electrons were measured in the transverse momentum range 0.5 < p(t) < 8 GeV/c. Predictions from a fixed-order perturbative QCD calculation with next-to-leading-log resummation agree with the data within the theoretical and experimental uncertainties. DOI: 10.1103/PhysRevD.86.112007
28.	Abelev, B., et al. (författare) Net-Charge Fluctuations in Pb-Pb Collisions at root s(NN)=2.76 TeV 2013 Ingår i: Physical Review Letters. - 1079-7114. ; 110:15 Tidskriftsartikel (refereegranskat)abstract We report the first measurement of the net-charge fluctuations in Pb-Pb collisions at root s(NN) = 2.76 TeV, measured with the ALICE detector at the CERN Large Hadron Collider. The dynamical fluctuations per unit entropy are observed to decrease when going from peripheral to central collisions. An additional reduction in the amount of fluctuations is seen in comparison to the results from lower energies. We examine the dependence of fluctuations on the pseudorapidity interval, which may account for the dilution of fluctuations during the evolution of the system. We find that the fluctuations at the LHC are smaller compared to the measurements at the BNL Relativistic Heavy Ion Collider, and as such, closer to what has been theoretically predicted for the formation of a quark-gluon plasma. DOI: 10.1103/PhysRevLett.110.152301
29.	Abelev, B., et al. (författare) Production of Muons from Heavy Flavor Decays at Forward Rapidity in pp and Pb-Pb Collisions at root s(NN)=2.76 TeV 2012 Ingår i: Physical Review Letters. - 1079-7114. ; 109:11 Tidskriftsartikel (refereegranskat)abstract The ALICE Collaboration has measured the inclusive production of muons from heavy-flavor decays at forward rapidity, 2.5 < y < 4, in pp and Pb-Pb collisions at root s(NN) = 2.76 TeV. The p(t)-differential inclusive cross section of muons from heavy-flavor decays in pp collisions is compared to perturbative QCD calculations. The nuclear modification factor is studied as a function of p(t) and collision centrality. A weak suppression is measured in peripheral collisions. In the most central collisions, a suppression of a factor of about 3-4 is observed in 6 < p(t) < 10 GeV/c. The suppression shows no significant p(t) dependence.
30.	Abelev, B., et al. (författare) Charge separation relative to the reaction plane in Pb-Pb collisions at root s(NN)=2.76 TeV 2013 Ingår i: Physical Review Letters. - 1079-7114. ; 110:1 Tidskriftsartikel (refereegranskat)abstract Measurements of charge-dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at root s(NN) = 2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudorapidity range vertical bar eta vertical bar < 0.8 are presented as a function of the collision centrality, particle separation in pseudorapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge-dependent azimuthal correlations observed at RHIC and LHC energies. DOI: 10.1103/PhysRevLett.110.012301
31.	Abelev, B., et al. (författare) (KsKs0)-K-0 correlations in pp collisions at root s=7 TeV from the LHC ALICE experiment 2012 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 717:1-3, s. 151-161 Tidskriftsartikel (refereegranskat)abstract Identical neutral kaon pair correlations are measured in root s = 7 TeV pp collisions in the ALICE experiment. One-dimensional (KsKs0)-K-0 correlation functions in terms of the invariant momentum difference of kaon pairs are formed in two multiplicity and two transverse momentum ranges. The femtoscopic parameters for the radius and correlation strength of the kaon source are extracted. The fit includes quantum statistics and final-state interactions of the a(0)/f(0) resonance. (KsKs0)-K-0 correlations show an increase in radius for increasing multiplicity and a slight decrease in radius for increasing transverse mass, mT, as seen in pi pi correlations in pp collisions and in heavy-ion collisions. Transverse mass scaling is observed between the (KsKs0)-K-0 and pi pi radii. Also, the first observation is made of the decay of the f(2)'(1525) meson into the (KsKs0)-K-0 channel in pp collisions. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
32.	Abelev, B., et al. (författare) Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at root S-NN=2.76 TeV 2013 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 18-28 Tidskriftsartikel (refereegranskat)abstract The elliptic, v(2), triangular, v(3), and quadrangular, v(4), azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions, and (anti-)protons in Pb-Pb collisions at root S-NN = 2.76 TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range vertical bar eta vertical bar < 0.8 at different collision centralities and as a function of transverse momentum, p(T), out to p(T) = 20 GeV/c. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for p(T) > 8 GeV/c. The small p(T) dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to p(T) = 8 GeV/c. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least p(T) = 8 GeV/c indicating that the particle type dependence persists out to high p(T). (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
33.	Abelev, B., et al. (författare) Multi-strange baryon production in pp collisions at root s=7 TeV with ALICE 2012 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 712:4-5, s. 309-318 Tidskriftsartikel (refereegranskat)abstract A measurement of the multi-strange Xi(-) and Omega(-) baryons and their antiparticles by the ALICE experiment at the CERN Large Hadron Collider (LHC) is presented for inelastic proton-proton collisions at a centre-of-mass energy of 7 TeV. The transverse momentum (p(T)) distributions were studied at mid-rapidity (vertical bar y vertical bar < 0.5) in the range of 0.6 < p(T) < 8.5 GeV/c Xi(-) for and Xi(+) baryons, and in the range of 0.8 < P-T < 5 GeV/c for Omega(-) and<(Omega)over bar>(+). Baryons and antibaryons were measured as separate particles and we find that the baryon to antibaryon ratio of both particle species is consistent with unity over the entire range of the measurement. The statistical precision of the current data has allowed us to measure a difference between the mean p(T) of Xi(-) ((Xi) over bar)(+) and Omega(-) ((Omega) over bar (+)). Particle yields, mean pi, and the spectra in the intermediate pi range are not well described by the PYTHIA Perugia 2011 tune Monte Carlo event generator, which has been tuned to reproduce the early LHC data. The discrepancy is largest for Omega(-)((Omega) over bar (+)). This PYTHIA tune approaches the pi spectra of Xi(-) and Xi(+) baryons below p(T) <0.85 GeV/c and describes the Xi(-) and Xi(+) spectra above p(T) > 6.0 GeV/c. We also illustrate the difference between the experimental data and model by comparing the corresponding ratios of (Omega(-) +(Omega) over bar (+))/(Xi(-) + Xi(+)) as a function of transverse mass. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
34.	Abelev, B., et al. (författare) Suppression of high transverse momentum D mesons in central Pb-Pb collisions at root s(NN)=2.76 TeV 2012 Ingår i: Journal of High Energy Physics. - 1029-8479. ; :9 Tidskriftsartikel (refereegranskat)abstract The production of the prompt charm mesons D-0, D+, D*(+), and their antiparticles, was measured with the ALICE detector in Pb-Pb collisions at the LHC, at a centre-of-mass energy root s(NN) = 2.76 TeV per nucleon-nucleon collision. The p(t)-differential production yields in the range 2 < p(t) < 16 GeV/c at central rapidity, vertical bar y vertical bar < 0.5, were used to calculate the nuclear modification factor R-AA with respect to a proton-proton reference obtained from the cross section measured at root s = 7 TeV and scaled to root s = 2.76 TeV. For the three meson species, R-AA shows a suppression by a factor 3-4, for transverse momenta larger than 5 GeV/c in the 20% most central collisions. The suppression is reduced for peripheral collisions.
35.	Abelev, B., et al. (författare) Transverse sphericity of primary charged particles in minimum bias proton-proton collisions at root s=0.9, 2.76 and 7 TeV 2012 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 72:9 Tidskriftsartikel (refereegranskat)abstract Measurements of the sphericity of primary charged particles in minimum bias proton-proton collisions at root s = 0.9, 2.76 and 7 TeV with the ALICE detector at the LHC are presented. The observable is measured in the plane perpendicular to the beam direction using primary charged tracks with p(T) > 0.5 GeV/c in vertical bar eta vertical bar < 0.8. The mean sphericity as a function of the charged particle multiplicity at mid-rapidity (N-ch) is reported for events with different p(T) scales ("soft" and "hard") defined by the transverse momentum of the leading particle. In addition, the mean charged particle transverse momentum versus multiplicity is presented for the different event classes, and the sphericity distributions in bins of multiplicity are presented. The data are compared with calculations of standard Monte Carlo event generators. The transverse sphericity is found to grow with multiplicity at all collision energies, with a steeper rise at low N-ch, whereas the event generators show an opposite tendency. The combined study of the sphericity and the mean p(T) with multiplicity indicates that most of the tested event generators produce events with higher multiplicity by generating more back-to-back jets resulting in decreased sphericity (and isotropy). The PYTHIA6 generator with tune PERUGIA-2011 exhibits a noticeable improvement in describing the data, compared to the other tested generators.
36.	Aamodt, K., et al. (författare) Higher Harmonic Anisotropic Flow Measurements of Charged Particles in Pb-Pb Collisions at root s(NN)=2.76 TeV 2011 Ingår i: Physical Review Letters. - 1079-7114. ; 107:3 Tidskriftsartikel (refereegranskat)abstract We report on the first measurement of the triangular nu(3), quadrangular nu(4), and pentagonal nu(5) charged particle flow in Pb-Pb collisions at root s(NN) = 2.76 TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show that the triangular flow can be described in terms of the initial spatial anisotropy and its fluctuations, which provides strong constraints on its origin. In the most central events, where the elliptic flow nu(2) and nu(3) have similar magnitude, a double peaked structure in the two-particle azimuthal correlations is observed, which is often interpreted as a Mach cone response to fast partons. We show that this structure can be naturally explained from the measured anisotropic flow Fourier coefficients.
37.	Abelev, B., et al. (författare) Measurement of the Cross Section for Electromagnetic Dissociation with Neutron Emission in Pb-Pb Collisions at root s(NN)=2.76 TeV 2012 Ingår i: Physical Review Letters. - 1079-7114. ; 109:25 Tidskriftsartikel (refereegranskat)abstract The first measurement of neutron emission in electromagnetic dissociation of Pb-208 nuclei at the LHC is presented. The measurement is performed using the neutron zero degree calorimeters of the ALICE experiment, which detect neutral particles close to beam rapidity. The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at root s(NN) = 2.76 TeV with neutron emission are sigma(singleEMD) = 187.4 +/- 0.2(stat)(-11.2)(+13.2) (syst) b and sigma(mutualEMD) = 5. 7 +/- 0.1(stat) +/- 0.4(syst) b, respectively. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model. DOI: 10.1103/PhysRevLett.109.252302
38.	Abelev, B., et al. (författare) Production of K(892)(0) and phi(1020) in pp collisions at root s=7 TeV 2012 Ingår i:* European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 72:10 Tidskriftsartikel (refereegranskat)abstract The production of K(892)(0) and phi(1020) in pp collisions at root s = 7 TeV was measured by the ALICE experiment at the LHC. The yields and the transverse momentum spectra d(2)N/dydp(T) at midrapidity vertical bar y vertical bar < 0.5 in the range 0 < p(T) < 6 GeV/c for K(892)(0) and 0.4 < p(T) < 6 GeV/c for phi(1020) are reported and compared to model predictions. Using the yield of pions, kaons, and Omega baryons measured previously by ALICE at root s = 7 TeV, the ratios K/K-, phi/K, phi/ K-, phi/pi(-), and (Omega + <(Omega)over bar>)/phi are presented. The values of the K/K-, phi/K and phi/K- ratios are similar to those found at lower centre-of-mass energies. In contrast, the phi/pi(-) ratio, which has been observed to increase with energy, seems to saturate above 200 GeV. The (Omega + (Omega) over bar)/phi ratio in the p(T) range 1-5 GeV/ c is found to be in good agreement with the prediction of the HIJING/B (B) over bar v2.0model with a strong colour field.
39.	Abelev, B., et al. (författare) Heavy flavour decay muon production at forward rapidity in proton-proton collisions at root s=7 TeV 2012 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 708:3-5, s. 265-275 Tidskriftsartikel (refereegranskat)abstract The production of muons from heavy flavour decays is measured at forward rapidity in proton-proton collisions at root s = 7 TeV collected with the ALICE experiment at the LHC. The analysis is carried out on a data sample corresponding to an integrated luminosity L-int = 16.5 nb(-1). The transverse momentum and rapidity differential production cross sections of muons from heavy flavour decays are measured in the rapidity range 2.5 < y <4, over the transverse momentum range 2 < p(t) < 12 GeV/c. The results are compared to predictions based on perturbative QCD calculations. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
40.	Abelev, B., et al. (författare) Inclusive J/psi production in pp collisions at root s=2.76 TeV 2012 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 718:2, s. 295-306 Tidskriftsartikel (refereegranskat)abstract The ALICE Collaboration has measured inclusive J/psi production in pp collisions at a center-of-mass energy root s = 2.76 TeV at the LHC. The results presented in this Letter refer to the rapidity ranges vertical bar y vertical bar < 0.9 and 2.5 < y <4 and have been obtained by measuring the electron and muon pair decay channels, respectively. The integrated luminosities for the two channels are L-int(e) = 1.1 nb(-1) and L-int(mu) = 19.9 nb(-1), and the corresponding signal statistics are N-J/psi(e+e-) = 59 +/- 14 and N-J/psi(mu+mu-) = 1364 +/- 53. We present d sigma(J/psi)/dy for the two rapidity regions under study and, for the forward-y range, d(2)sigma(J/psi)/dydp(t) in the transverse momentum domain 0 < p(t) < 8 GeV/c. The results are compared with previously published results at root s = 7 TeV and with theoretical calculations. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
41.	Abelev, B., et al. (författare) J/psi Suppression at Forward Rapidity in Pb-Pb Collisions at root s(NN)=2.76 TeV 2012 Ingår i: Physical Review Letters. - 1079-7114. ; 109:7 Tidskriftsartikel (refereegranskat)abstract The ALICE experiment has measured the inclusive J/psi production in Pb-Pb collisions at root s(NN) = 2.76 TeV down to zero transverse momentum in the rapidity range 2.5 < y < 4. A suppression of the inclusive J/psi yield in Pb-Pb is observed with respect to the one measured in pp collisions scaled by the number of binary nucleon-nucleon collisions. The nuclear modification factor, integrated over the 0%-80% most central collisions, is 0.545 +/- 0.032(stat) +/- 0.083dsyst_ and does not exhibit a significant dependence on the collision centrality. These features appear significantly different from measurements at lower collision energies. Models including J/psi production from charm quarks in a deconfined partonic phase can describe our data.
42.	Abelev, B., et al. (författare) Measurement of event background fluctuations for charged particle jet reconstruction in Pb-Pb collisions at root s(NN)=2.76 TeV 2012 Ingår i: Journal of High Energy Physics. - 1029-8479. ; :3 Tidskriftsartikel (refereegranskat)abstract The effect of event background fluctuations on charged particle jet reconstruction in Pb-Pb collisions at root s(NN) = 2.76 TeV has been measured with the ALICE experiment. The main sources of non-statistical fluctuations are characterized based purely on experimental data with an unbiased method, as well as by using single high p(t) particles and simulated jets embedded into real Pb-Pb events and reconstructed with the anti-k(t) jet finder. The influence of a low transverse momentum cut-off on particles used in the jet reconstruction is quantified by varying the minimum track p(t) between 0.15 GeV/c and 2 GeV/c. For embedded jets reconstructed from charged particles with p(t) > 0.15 GeV/c, the uncertainty in the reconstructed jet transverse momentum due to the heavy-ion background is measured to be 11.3 GeV/c (standard deviation) for the 10% most central Pb-Pb collisions, slightly larger than the value of 11.0 GeV/c measured using the unbiased method. For a higher particle transverse momentum threshold of 2 GeV/c, which will generate a stronger bias towards hard fragmentation in the jet finding process, the standard deviation of the fluctuations in the reconstructed jet transverse momentum is reduced to 4.8-5.0 GeV/c for the 10% most central events. A non-Gaussian tail of the momentum uncertainty is observed and its impact on the reconstructed jet spectrum is evaluated for varying particle momentum thresholds, by folding the measured fluctuations with steeply falling spectra.
43.	Aamodt, K., et al. (författare) Charged-particle multiplicity measurement in proton-proton collisions at root s=7 TeV with ALICE at LHC 2010 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 68:3-4, s. 345-354 Tidskriftsartikel (refereegranskat)abstract The pseudorapidity density and multiplicity distribution of charged particles produced in proton-proton collisions at the LHC, at a centre-of-mass energy root s = 7 TeV, were measured in the central pseudorapidity region vertical bar eta vertical bar < 1. Comparisons are made with previous measurements at root s = 0.9 TeV and 2.36 TeV. At root s = 7 TeV, for events with at least one charged particle in \|eta vertical bar\| < 1, we obtain dN(ch)/d eta = 6.01 +/- 0.01(stat.)(-0.12)(+0.20) (syst.). This corresponds to an increase of 57.6%+/-0.4%(stat.)(-1.8%)(+3.6) (syst.) relative to collisions at 0.9 TeV, significantly higher than calculations from commonly used models. The multiplicity distribution at 7 TeV is described fairly well by the negative binomial distribution.
44.	Aamodt, K., et al. (författare) Midrapidity Antiproton-to-Proton Ratio in pp Collisons root s=0.9 and 7 TeV Measured by the ALICE Experiment 2010 Ingår i: Physical Review Letters. - 1079-7114. ; 105:7 Tidskriftsartikel (refereegranskat)abstract The ratio of the yields of antiprotons to protons in pp collisions has been measured by the ALICE experiment at root s = 0.9 and 7 TeV during the initial running periods of the Large Hadron Collider. The measurement covers the transverse momentum interval 0.45 < p(t) < 1.05 GeV/c and rapidity vertical bar y vertical bar < 0.5. The ratio is measured to be R-vertical bar y vertical bar<0.5 = 0.957 +/- 0.006(stat) +/- 0.0014(syst) at 0.9 Tev and R-vertical bar y vertical bar<0.5 = 0.991 +/- 0.005 +/- 0.014(syst) at 7 TeV and it is independent of both rapidity and transverse momentum. The results are consistent with the conventional model of baryon-number transport and set stringent limits on any additional contributions to baryon-number transfer over very large rapidity intervals in pp collisions.
45.	Aamodt, K., et al. (författare) Production of pions, kaons and protons in pp collisions at root s=900 GeV with ALICE at the LHC 2011 Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 71:6 Tidskriftsartikel (refereegranskat)abstract The production of pi(+), pi(-), K+, K-, p, and (p) over bar at mid-rapidity has been measured in proton-proton collisions at root s = 900 GeV with the ALICE detector. Particle identification is performed using the specific energy loss in the inner tracking silicon detector and the time projection chamber. In addition, time-of-flight information is used to identify hadrons at higher momenta. Finally, the distinctive kink topology of the weak decay of charged kaons is used for an alternative measurement of the kaon transverse momentum (p(t)) spectra. Since these various particle identification tools give the best separation capabilities over different momentum ranges, the results are combined to extract spectra from p(t) = 100 MeV/c to 2.5 GeV/c. The measured spectra are further compared with QCD-inspired models which yield a poor description. The total yields and the mean pt are compared with previous measurements, and the trends as a function of collision energy are discussed.
46.	Aamodt, K., et al. (författare) Rapidity and transverse momentum dependence of inclusive J/psi production in pp collisions at root s=7 TeV 2011 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 704:5, s. 442-455 Tidskriftsartikel (refereegranskat)abstract The ALICE experiment at the LHC has studied inclusive J/psi production at central and forward rapidities in pp collisions at root s = 7 TeV. In this Letter, we report on the first results obtained detecting the J/psi through the dilepton decay into e(+)e(-) and mu(+)mu(-) pairs in the rapidity ranges vertical bar y vertical bar < 0.9 and 2.5 < y < 4, respectively, and with acceptance down to zero PT. In the dielectron channel the analysis was carried Out on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1) and the number of signal events is N-J/psi = 352 +/- 32 (stat.) +/- 28 (syst.): the corresponding figures in the dimuon channel are L-int = 15.6 nb(-1) and N-J/psi = 1924 +/- 77 (stat.) +/- 144 (syst.). The measured production cross sections are sigma(J/psi) (vertical bar y vertical bar < 0.9) = 10.7 +/- 1.0 (stat.) +/- 1.6 (syst.)(-2.3)(+1.6) (syst.pol.) mu b and sigma(J/psi) (2.5 < y < 4) = 6.31 +/- 0.25 (stat.) +/- 0.76 (syst.)(-1.96)(+0.95) (syst.pol.) mu b. The differential cross sections, in transverse momentum and rapidity, of the J/psi were also measured. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved.
47.	Aamodt, K., et al. (författare) Transverse momentum spectra of charged particles in proton-proton collisions at root s=900 GeV with ALICE at the LHC 2010 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 693:2, s. 53-68 Tidskriftsartikel (refereegranskat)abstract The inclusive charged particle transverse momentum distribution is measured in proton-proton collisions at root s = 900 GeV at the LHC using the ALICE detector. The measurement is performed in the central pseudorapidity region (vertical bar eta vertical bar < 0.8) over the transverse momentum range 0.15 < p(T) < 10 GeV/c. The correlation between transverse momentum and particle multiplicity is also studied. Results are presented for inelastic (INEL) and non-single-diffractive (NSD) events. The average transverse momentum for vertical bar eta vertical bar < 0.8 is < p(T)>(INEL) = 0.483 +/- 0.001 (stat.) +/- 0.007 (syst.) GeV/c and < p(T)>(NSD) = 0.489 +/- 0.001 (stat.) +/- 0.007 (syst.) GeV/c, respectively. The data exhibit a slightly larger < p(T)> than measurements in wider pseudorapidity intervals. The results are compared to simulations with the Monte Carlo event generators PYTHIA and PHOJET. (C) 2010 Published by Elsevier B.V.
48.	Aamodt, K., et al. (författare) Two-pion Bose-Einstein correlations in pp collisions at root s=900 GeV 2010 Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 82:5 Tidskriftsartikel (refereegranskat)abstract We report on the measurement of two-pion correlation functions from pp collisions at root s = 900 GeV performed by the ALICE experiment at the Large Hadron Collider. Our analysis shows an increase of the Hanbury Brown-Twiss radius with increasing event multiplicity, in line with other measurements done in particle- and nuclear collisions. Conversely, the strong decrease of the radius with increasing transverse momentum, as observed at the Relativistic Heavy Ion Collider and at Tevatron, is not manifest in our data.
49.	Abelev, B., et al. (författare) J/psi Polarization in pp Collisions at root s=7 TeV 2012 Ingår i: Physical Review Letters. - 1079-7114. ; 108:8 Tidskriftsartikel (refereegranskat)abstract The ALICE Collaboration has studied J/psi production in pp collisions at root s = 7 TeV at the LHC through its muon pair decay. The polar and azimuthal angle distributions of the decay muons were measured, and results on the J/psi polarization parameters lambda(theta) and lambda(phi) were obtained. The study was performed in the kinematic region 2: 5 < y < 4, 2 < p(t) < 8 GeV/c, in the helicity and Collins-Soper reference frames. In both frames, the polarization parameters are compatible with zero, within uncertainties.
50.	Abelev, B., et al. (författare) Light vector meson production in pp collisions at root s=7 TeV ALICE Collaboration 2012 Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 710:4-5, s. 557-568 Tidskriftsartikel (refereegranskat)abstract The ALICE experiment has measured low-mass dimuon production in pp collisions at root s = 7 TeV in the dimuon rapidity region 2.5 < y < 4. The observed dimuon mass spectrum is described as a superposition of resonance decays (eta, rho, omega, eta', phi) into muons and semi-leptonic decays of charmed mesons. The measured production cross sections for omega and phi are sigma(omega)(1 < p(t) < 5 GeV/c. 2.5 < y < 4) = 5.28 +/- 0.54(stat) +/- 0.49(syst) mb and sigma(phi)(1 < p(t) < 5 GeV/c. 2.5 < y < 4) = 0.940 +/- 0.084(stat) +/- 0.076(syst) mb. The differential cross sections d(2)sigma/dy dp(t) are extracted as a function of p(t) for omega and phi. The ratio between the rho and omega cross section is obtained. Results for the phi are compared with other measurements at the same energy and with predictions by models. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.

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