Performance of the ATLAS Track Reconstruction Algorithms in Dense Environments in LHC run 2

ATLAS Collaboration, Paul Newman (Contributor)

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With the increase in energy of the Large Hadron Collider to a centre-of-mass energy of 13 TeV for Run 2, events with dense environments, such as in the cores of high-energy jets, became a focus for new physics searches as well as measurements of the Standard Model. These environments are characterized by charged-particle separations of the order of the tracking detectors sensor granularity. Basic track quantities are compared between 3.2 fb$^{-1}$ of data collected by the ATLAS experiment and simulation of proton-proton collisions producing high-transverse-momentum jets at a centre-of-mass energy of 13 TeV. The impact of charged-particle separations and multiplicities on the track reconstruction performance is discussed. The efficiency in the cores of jets with transverse momenta between 200 GeV and 1600 GeV is quantified using a novel, data-driven, method. The method uses the energy loss, dE/dx, to identify pixel clusters originating from two charged particles. Of the charged particles creating these clusters, the measured fraction that fail to be reconstructed is $0.061 \pm 0.006\textrm{(stat.)} \pm 0.014\textrm{(syst.)}$ and $0.093 \pm 0.017\textrm{(stat.)}\pm 0.021\textrm{(syst.)}$ for jet transverse momenta of 200-400 GeV and 1400-1600 GeV, respectively.
Original languageEnglish
Article number673
JournalEuropean Physical Journal C
Publication statusPublished - 11 Oct 2017

Bibliographical note

44 pages in total, author list starting page 28, 17 figures, 1 table, submitted to EPJC, All figures including auxiliary figures are available at


  • hep-ex


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