Showing papers by "M. Abolins published in 2017"
TL;DR: Topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS and is exploited to apply a local energy calibration and corrections depending on the nature of the cluster.
Abstract: The reconstruction of the signal from hadrons and jets emerging from the proton–proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In this, the clustering algorithm implicitly performs a topological noise suppression by removing cells with insignificant signals which are not in close proximity to cells with significant signals. The resulting topological cell clusters have shape and location information, which is exploited to apply a local energy calibration and corrections depending on the nature of the cluster. Topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.
438 citations
Aix-Marseille University1, University of Oklahoma2, University of Iowa3, Azerbaijan National Academy of Sciences4, Université Paris-Saclay5, University of Amsterdam6, Michigan State University7, University of California, Santa Cruz8, University of Sussex9, Tel Aviv University10, Technion – Israel Institute of Technology11, University of Oregon12, Stockholm University13, International Centre for Theoretical Physics14, AGH University of Science and Technology15, Brookhaven National Laboratory16, Northern Illinois University17, Ludwig Maximilian University of Munich18, Rutherford Appleton Laboratory19, University of Liverpool20, University of Belgrade21, University of Göttingen22, University of Granada23, Boston University24, Joint Institute for Nuclear Research25, University of Rome Tor Vergata26, Lund University27, Russian Academy of Sciences28, University of Bologna29, University of Victoria30, University of Grenoble31, National University of La Plata32, CERN33, National Technical University of Athens34, University of Chicago35, Columbia University36, University of Birmingham37, University of Copenhagen38, University of Washington39, Spanish National Research Council40, Lawrence Berkeley National Laboratory41, KEK42, Federal University of Rio de Janeiro43, Brandeis University44, University of Michigan45, University of Coimbra46, University of Lisbon47, University of Sheffield48, University of Geneva49, University of Texas at Austin50, Heidelberg University51, University of Milan52, National and Kapodistrian University of Athens53, Dresden University of Technology54, Budker Institute of Nuclear Physics55, IFAE56, University of Pisa57, National Research Nuclear University MEPhI58, Slovak Academy of Sciences59
TL;DR: In this paper, a direct search for lepton flavour violation in decays of the Higgs and Z bosons with the ATLAS detector at the LHC is presented, and upper limits on the lepton-flavour-violating branching ratios are set at the 95[Formula: see text] confidence level.
Abstract: Direct searches for lepton flavour violation in decays of the Higgs and Z bosons with the ATLAS detector at the LHC are presented. The following three decays are considered: [Formula: see text], [Formula: see text], and [Formula: see text]. The searches are based on the data sample of proton-proton collisions collected by the ATLAS detector corresponding to an integrated luminosity of 20.3 [Formula: see text] at a centre-of-mass energy of [Formula: see text] TeV. No significant excess is observed, and upper limits on the lepton-flavour-violating branching ratios are set at the 95[Formula: see text] confidence level: Br[Formula: see text], Br[Formula: see text], and Br[Formula: see text].
132 citations
TL;DR: The reconstruction and calibration algorithms used to calculate missing transverse momentum with the ATLAS detector exploit energy deposits in the calorimeter and tracks reconstructed in the inner detector as well as the muon spectrometer to suppress effects arising from additional proton–proton interactions concurrent with the hard-scatter processes.
Abstract: The reconstruction and calibration algorithms used to calculate missing transverse momentum ($E_{\rm T}^{\rm miss}$) with the ATLAS detector exploit energy deposits in the calorimeter and tracks reconstructed in the inner detector as well as the muon spectrometer. Various strategies are used to suppress effects arising from additional proton-proton interactions, called pileup, concurrent with the hard-scatter processes. Tracking information is used to distinguish contributions from the pileup interactions using their vertex separation along the beam axis. The performance of the $E_{\rm T}^{\rm miss}$ reconstruction algorithms, especially with respect to the amount of pileup, is evaluated using data collected in proton-proton collisions at a centre-of-mass energy of 8 TeV during 2012, and results are shown for a data sample corresponding to an integrated luminosity of 20.3 fb$^{-1}$. The results of simulation modelling of $E_{\rm T}^{\rm miss}$ in events containing a $Z$ boson decaying to two charged leptons (electrons or muons) or a $W$ boson decaying to a charged lepton and a neutrino is compared to data. The acceptance for different event topologies, with and without high transverse momentum neutrinos, is shown for a range of threshold criteria for $E_{\rm T}^{\rm miss}$, and estimates of the systematic uncertainties in the $E_{\rm T}^{\rm miss}$ measurements are presented.
68 citations
TL;DR: In this article, the authors proposed a method to find the optimal set of features for each node in a set of images, which can be found under doi:10.1140/epjc/s10052-016-3910-6
Abstract: The online version of the original article can be found under doi:10.1140/epjc/s10052-016-3910-6
15 citations