1,195 research outputs found
Measurements of the pseudorapidity dependence of the total transverse energy in proton-proton collisions at root s=7 TeV with ATLAS
No full textATLAS Collaboration contributor: Paul Douglas Jackson of SLAC National Accelerator Laboratory, Stanford CA, United States of America. Extent: 54This paper describes measurements of the sum of the transverse energy of particles as a function of particle pseudorapidity, η, in proton-proton collisions at a centre-of-mass energy, √s=7 TeV using the ATLAS detector at the Large Hadron Collider. The measurements are performed in the region |η| < 4.8 for two event classes: those requiring the presence of particles with a low transverse momentum and those requiring particles with a significant transverse momentum. In the second dataset measurements are made in the region transverse to the hard scatter. The distributions are compared to the predictions of various Monte Carlo event generators, which generally tend to underestimate the amount of transverse energy at high |η|.The ATLAS collaboratio
A Measurement of Jet Shapes in Proton-Proton Collisions at 7.0 TeV Center-of-Mass Energy with the ATLAS Detector at the Large Hadron Collider
No full textA study of jet shapes is presented using 300 nb−1 of proton-proton collision data collected at a center of mass energy of 7 TeV using the ATLAS detector at the Large Hadron Collider. The analysis includes jets with rapidity |y| < 2.8 and with calibrated transverse momentum 40 < pT < 600 GeV. Results are compared with several tuned Monte Carlo programs. Jets are found to be wider than predicted, although the evolution of the jet shape with transverse momentum is well described
Charged-particle multiplicities in pp interactions at measured with the ATLAS detector at the LHC
No full textThe first measurements from proton–proton collisions recorded with the ATLAS detector at the LHC are presented. Data were collected in December 2009 using a minimum-bias trigger during collisions at a centre-of-mass energy of 900 GeV. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transverse momentum and charged-particle multiplicity are measured for events with at least one charged particle in the kinematic range |η|<2.5 and pT>500 MeV. The measurements are compared to Monte Carlo models of proton–proton collisions and to results from other experiments at the same centre-of-mass energy. The charged-particle multiplicity per event and unit of pseudorapidity at η=0 is measured to be 1.333±0.003(stat.)±0.040(syst.), which is 5–15% higher than the Monte Carlo models predict
The Charged Particle Multiplicity at Center of Mass Energies from 900 GeV to 7 TeV Measured with the ATLAS Experiment at the Large Hadron Collider
No full textThe first measurements made by the ATLAS experiment at the LHC are presented. The charged particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transverse momentum and pseudorapidity are measured for events with at least one charged particle in the kinematic range |η| 500 MeV. The charged particle multiplicity distributions are measured at the three centre of mass energies at which protons have been collided in the LHC: 900 GeV, 2.36 TeV and 7 TeV. The results are compared to predictions from Monte Carlo models of proton-proton collisions. All models predicted a multiplicity at least 10% lower than was measured. They also failed to predict a sufficient increase in the multiplicity when the centre of mass energy increased from 900 GeV to 7 TeV. Updated models have already been produced using these data, which provide a significantly better description of the properties of proton-proton collisions at LHC energies
Search for the Standard Model Higgs boson in the H → τ +τ - decay mode in √s = 7TeV pp collisions with ATLAS
No full textContains fulltext :
103747.pdf (Publisher’s version ) (Open Access
Measurement of inclusive jet and dijet cross sections in proton-proton collisions at 7 TeV centre-of-mass energy with the ATLAS detector
No full textJet cross sections have been measured for the first time in proton-proton collisions at a centre-of-mass energy of 7 TeV using the ATLAS detector. The measurement uses an integrated luminosity of 17 nb−1 recorded at the Large Hadron Collider. The anti-k t algorithm is used to identify jets, with two jet resolution parameters, R=0.4 and 0.6. The dominant uncertainty comes from the jet energy scale, which is determined to within 7% for central jets above 60 GeV transverse momentum. Inclusive single-jet differential cross sections are presented as functions of jet transverse momentum and rapidity. Dijet cross sections are presented as functions of dijet mass and the angular variable χ. The results are compared to expectations based on next-to-leading-order QCD, which agree with the data, providing a validation of the theory in a new kinematic regime
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