SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "LAR1:uu ;pers:(Tylmad Maja)"

Sökning: LAR1:uu > Tylmad Maja

Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Aaboud, M, et al. (författare)
  • Operation and performance of the ATLAS Tile Calorimeter in Run 1
  • 2018
  • Ingår i: European Physical Journal C. - Springer. - 1434-6044. ; 78
  • Tidskriftsartikel (refereegranskat)abstract
    • The Tile Calorimeter is the hadron calorimeter covering the central region of the ATLAS experiment at the Large Hadron Collider. Approximately 10,000 photomultipliers collect light from scintillating tiles acting as the active material sandwiched between slabs of steel absorber. This paper gives an overview of the calorimeter’s performance during the years 2008–2012 using cosmic-ray muon events and proton–proton collision data at centre-of-mass energies of 7 and 8 TeV with a total integrated luminosity of nearly 30 fb−1. The signal reconstruction methods, calibration systems as well as the detector operation status are presented. The energy and time calibration methods performed excellently, resulting in good stability of the calorimeter response under varying conditions during the LHC Run 1. Finally, the Tile Calorimeter response to isolated muons and hadrons as well as to jets from proton–proton collisions is presented. The results demonstrate excellent performance in accord with specifications mentioned in the Technical Design Report.
2.
  • Aad, G., et al. (författare)
  • A measurement of the ratio of the production cross sections for W and Z bosons in association with jets with the ATLAS detector
  • 2014
  • Ingår i: European Physical Journal C. Particles and Fields. - Springer. - 1434-6044. ; 74:12
  • Tidskriftsartikel (refereegranskat)abstract
    • The ratio of the production cross sections for W and Z bosons in association with jets has been measured in proton-proton collisions at root s = 7 TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is based on the entire 2011 dataset, corresponding to an integrated luminosity of 4.6 fb(-1). Inclusive and differential cross-section ratios for massive vector bosons decaying to electrons and muons are measured in association with jets with transverse momentum p(T) > 30 GeV and jet rapidity vertical bar y vertical bar < 4.4. The measurements are compared to next-to-leading-order perturbative QCD calculations and to predictions from different Monte Carlo generators implementing leading-order matrix elements supplemented by parton showers.
3.
  • Aad, Georges, et al. (författare)
  • A measurement of the ratio of the W and Z cross sections with exactly one associated jet in pp collisions at root s=7 TeV with ATLAS
  • 2012
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 708:3-5, s. 221-240
  • Tidskriftsartikel (refereegranskat)abstract
    • The ratio of production cross sections of the W and Z bosons with exactly one associated jet is presented as a function of jet transverse momentum threshold. The measurement has been designed to maximise cancellation of experimental and theoretical uncertainties, and is reported both within a particle-level kinematic range corresponding to the detector acceptance and as a total cross-section ratio. Results are obtained with the ATLAS detector at the LHC in pp collisions at a centre-of-mass energy of 7 TeV using an integrated luminosity of 33 pb(-1). The results are compared with perturbative leading-order, leading-log, and next-to-leading-order QCD predictions, and are found to agree within experimental and theoretical uncertainties. The ratio is measured for events with a single jet with p(T) > 30 GeV to be 8.73 +/- 0.30(stat) +/- 0.40(syst) in the electron channel, and 8.49 +/- 0.23(stat) +/- 0.33(syst) in the muon channel. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.
  •  
4.
  • Aad, G., et al. (författare)
  • A neural network clustering algorithm for the ATLAS silicon pixel detector
  • 2014
  • Ingår i: Journal of Instrumentation. - IOP Publishing. - 1748-0221. ; 9
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel technique to identify and split clusters created by multiple charged particles in the ATLAS pixel detector using a set of artificial neural networks is presented. Such merged clusters are a common feature of tracks originating from highly energetic objects, such as jets. Neural networks are trained using Monte Carlo samples produced with a detailed detector simulation. This technique replaces the former clustering approach based on a connected component analysis and charge interpolation. The performance of the neural network splitting technique is quantified using data from proton-proton collisions at the LHC collected by the ATLAS detector in 2011 and from Monte Carlo simulations. This technique reduces the number of clusters shared between tracks in highly energetic jets by up to a factor of three. It also provides more precise position and error estimates of the clusters in both the transverse and longitudinal impact parameter resolution.
5.
  • Aad, G., et al. (författare)
  • A Particle Consistent with the Higgs Boson Observed with the ATLAS Detector at the Large Hadron Collider
  • 2012
  • Ingår i: Science. - 0036-8075. ; 338:6114, s. 1576-1582
  • Tidskriftsartikel (refereegranskat)abstract
    • Nearly 50 years ago, theoretical physicists proposed that a field permeates the universe and gives energy to the vacuum. This field was required to explain why some, but not all, fundamental particles have mass. Numerous precision measurements during recent decades have provided indirect support for the existence of this field, but one crucial prediction of this theory has remained unconfirmed despite 30 years of experimental searches: the existence of a massive particle, the standard model Higgs boson. The ATLAS experiment at the Large Hadron Collider at CERN has now observed the production of a new particle with a mass of 126 giga-electron volts and decay signatures consistent with those expected for the Higgs particle. This result is strong support for the standard model of particle physics, including the presence of this vacuum field. The existence and properties of the newly discovered particle may also have consequences beyond the standard model itself.
  •  
6.
  • Aad, G., et al. (författare)
  • A search for flavour changing neutral currents in top-quark decays in pp collision data collected with the ATLAS detector at root s=7 TeV
  • 2012
  • Ingår i: Journal of High Energy Physics. - Springer. - 1029-8479. ; :9
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for flavour changing neutral current (FCNC) processes in top-quark decays by the ATLAS Collaboration is presented. Data collected from pp collisions at the LHC at a centre-of-mass energy of root s = 7 TeV during 2011, corresponding to an integrated luminosity of 2.1 fb(-1), were used. A search was performed for top-quark pair-production events, with one top quark decaying through the t -> Zq FCNC (q = u, c) channel, and the other through the Standard Model dominant mode t -> Wb. Only the decays of the Z boson to charged leptons and leptonic W-boson decays were considered as signal. Consequently, the final-state topology is characterised by the presence of three isolated charged leptons, at least two jets and missing transverse momentum from the undetected neutrino. No evidence for an FCNC signal was found. An upper limit on the t -> Zq branching ratio of BR(t -> Zq) < 0.73% is set at the 95% confidence level.
7.
  • Aad, G., et al. (författare)
  • A search for high-mass resonances decaying to tau(+)tau(-) in pp collisions at root s=7 TeV with the ATLAS detector
  • 2013
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 719:4-5, s. 242-260
  • Tidskriftsartikel (refereegranskat)abstract
    • This Letter presents a search for high-mass resonances decaying into tau(+)tau(-) final states using proton-proton collisions at root s = 7 TeV produced by the Large Hadron Collider. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 4.6 fb(-1). No statistically significant excess above the Standard Model expectation is observed; 95% credibility upper limits are set on the cross section times branching fraction of Z' resonances decaying into tau(+)tau(-) pairs as a function of the resonance mass. As a result, Z' bosons of the Sequential Standard Model with masses less than 1.40 TeV are excluded at 95% credibility. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
8.
  • Aad, G., et al. (författare)
  • A search for high-mass resonances decaying to tau(+)tau(-) in pp collisions at root s=8 TeV with the ATLAS detector
  • 2015
  • Ingår i: Journal of High Energy Physics. - Springer. - 1029-8479. ; :7
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for high-mass resonances decaying into tau(+)tau(-) final states using proton-proton collisions at root s = 8 TeV produced by the Large Hadron Collider is presented. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 19.5-20.3 fb(-1). No statistically significant excess above the Standard Model expectation is observed; 95% credibility upper limits are set on the cross section times branching fraction of Z' resonances decaying into tau(+)tau(-) pairs as a function of the resonance mass. As a result, Z' bosons of the Sequential Standard Model with masses less than 2.02 TeV are excluded at 95% credibility. The impact of the fermionic couplings on the Z' acceptance is investigated and limits are also placed on a Z' model that exhibits enhanced couplings to third-generation fermions.
9.
  • Aad, G., et al. (författare)
  • A search for new physics in dijet mass and angular distributions in pp collisions at root s=7 TeV measured with the ATLAS detector
  • 2011
  • Ingår i: New Journal of Physics. - IOP Publishing. - 1367-2630. ; 13
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for new interactions and resonances produced in LHC proton-proton (pp) collisions at a centre-of-mass energy root s = 7 TeV was performed with the ATLAS detector. Using a dataset with an integrated luminosity of 36 pb(-1), dijet mass and angular distributions were measured up to dijet masses of similar to 3.5 TeV and were found to be in good agreement with Standard Model predictions. This analysis sets limits at 95% CL on various models for new physics: an excited quark is excluded for mass between 0.60 and 2.64 TeV, an axigluon hypothesis is excluded for axigluon masses between 0.60 and 2.10 TeV and quantum black holes are excluded in models with six extra space-time dimensions for quantum gravity scales between 0.75 and 3.67 TeV. Production cross section limits as a function of dijet mass are set using a simplified Gaussian signal model to facilitate comparisons with other hypotheses. Analysis of the dijet angular distribution using a novel technique simultaneously employing the dijet mass excludes quark contact interactions with a compositeness scale 3 below 9.5 TeV.
10.
  • Aad, G., et al. (författare)
  • A search for prompt lepton-jets in pp collisions at root s=7 TeV with the ATLAS detector
  • 2013
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 719:4-5, s. 299-317
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for a light (mass < 2 GeV) boson predicted by Hidden Valley supersymmetric models that decays into a final state consisting of collimated muons or electrons, denoted "lepton-jets". The analysis uses 5 fb(-1) of root s = 7 TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider to search for the following signatures: single lepton-jets with at least four muons; pairs of lepton-jets, each with two or more muons; and pairs of lepton-jets with two or more electrons. This study finds no statistically significant deviation from the Standard Model prediction and places 95% confidence-level exclusion limits on the production cross section times branching ratio of light bosons for several parameter sets of a Hidden Valley model. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
Skapa referenser, mejla, bekava och länka
 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy