34 research outputs found
Recent Results on Soft QCD Topics from ATLAS
No full textThe ATLAS collaboration has performed several measurements in special data sets with low LHC beam currents, recorded at a center-of-mass energy of 13 TeV: Measurements of the inclusive charged-particle multiplicity and its dependence on transverse momentum and pseudorapidity are presented and compared with predictions of various MC generators. The collaboration has also performed measurements of the number and transverse-momentum sum of charged particles as a function of properties of the leading high pT track in the event at a center-of-mass energy of 13 TeV. The results are compared to predictions of several MC generators. In addition, the total inelastic proton-proton cross section and the diffractive part of the inelastic cross section was measured, using special forward scintillators or the calorimeters. The latter result completes the measurement of the elastic pp cross section in a dedicated run with high beta* optics at 8 TeV centre-of-mass energy with the ALFA Roman Pot detector. From the extrapolation of the differential elastic cross section to t=0, using the optical theorem, the total cross section is extracted with the luminosity-dependent method with high precision. Furthermore, the nuclear slope of the elastic t-spectrum and the total elastic and inelastic cross sections are determined. Finally, the collaboration has studied the hard double parton interactions (DPI) in events with 4 hadronic jets and translated into a measurement of the effective DPI cross section. Several DPI-sensitive variables are unfolded to particle level and compared to predictions of different MC models
Measuring Jet substructure observables at the ATLAS experiment
No full textJet substructure observables have significantly extended the search program for physics beyond the Standard Model at the Large Hadron Collider. The state-of-the-art tools have been motivated by theoretical calculations, but there has never been a direct comparison between data and calculations of jet substructure observables that are accurate beyond leading-logarithm approximation. Such ob- servables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. The ATLAS collaboration has recently per- formed several measurements of precision jet substructure at 13 TeV that will significantly extend our understanding of both the perturbative and non-perturbative aspects of jet formation. These measurements of jet mass in various topologies as well as other properties of jet fragmentation such as charged-particle multiplicity and the properties of gluon splitting to bottom quarks are unfolded to correct for detector effects and compared with a variety of predictions
Author Correction: A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery
No full textIn the version of this article initially published, the ATLAS Collaboration
author names, affiliations and acknowledgements were omitted and
have now been included in the HTML and PDF versions of the article
General features of pp interactions at 32 GeV/c
No full textThe general features of pp interactions at 32 GeV/c are analysed in a bubble chamber experiment with a statistics of 5.2 μb/event. The inclusive production of neutral strange particles and pions is analysed and compared to results obtained at other energies and in pp interactions. Total cross sections are determined for various 4C reactions and the relative contributions of diffractive dissociation and ΔΔ production to the reaction pp→ppπ+π- are estimated. © 1977.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Evidence of W gamma gamma Production in pp Collisions at root s=8 TeV and Limits on Anomalous Quartic Gauge Couplings with the ATLAS Detector
No full textPublished by the American Physical Society under the terms of
the Creative Commons Attribution 3.0 License. Further distribution
of this work must maintain attribution to the author(s) and
the published article’s title, journal citation, and DOISCOAP
Inclusive production of neutral strange particles in {Mathematical expression} interactions at 32 GeV/c
No full textThe inclusive Kn, ¶, and {Mathematical expression} production has been studied in a {Mathematical expression} experiment performed in the Mirabelle bubble chamber at an incident beam momentum of 32.1 GeV/c. Total, topological and differential cross sections are presented and compared with those obtained at other energies. The invariant structure functions have been parametrised in the fragmentation region by a power law and are consistent with the expectations based on quark counting rules. © 1981 Springer-Verlag.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Author Correction: A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery
No full textSearch for dark matter produced in association with a hadronically decaying vector boson in pp collisions at =13 TeV with the ATLAS detector
No full textSee paper for full list of authors - 10 pages plus author list + cover pages (30 pages total), 5 figures, 2 tables, submitted to PLB, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2015-08/International audienceA search is presented for dark matter produced in association with a hadronically decaying W or Z boson using 3.2 /fb of pp collisions at =13 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet compatible with a W or Z boson and with large missing transverse momentum are analysed. The data are consistent with the Standard Model predictions and are interpreted in terms of both an effective field theory and a simplified model containing dark matter
Evidence for Electroweak Production of W(+/-)W(+/-)jj in pp Collisions at root s=8 TeV with the ATLAS Detector
No full textFurther distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.This Letter presents the first study of W±W±jj, same-electric-charge diboson production in association with two jets, using 20.3 fb-1 of proton-proton collision data at √s=8 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with two reconstructed same-charge leptons (e±e±, e±μ±, and μ±μ±) and two or more jets are analyzed. Production cross sections are measured in two fiducial regions, with different sensitivities to the electroweak and strong production mechanisms. First evidence for W±W±jj production and electroweak-only W±W±jj production is observed with a significance of 4.5 and 3.6 standard deviations, respectively. The measured production cross sections are in agreement with standard model predictions. Limits at 95% confidence level are set on anomalous quartic gauge couplings
Search for Higgs bosons decaying to in the final state in collisions at 8 TeV with the ATLAS experiment
No full textSee paper for full list of authors – 11 pages plus author list + cover pages (24 pages total), 6 figures, 4 tables, submitted to Phys. Rev. D, All figures including auxillary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2014-02/International audienceA search for the decay to a pair of new particles of either the 125 GeV Higgs boson () or a second CP-even Higgs boson () is presented. The dataset correspods to an integrated luminosity of 20.3 fb of collisions at 8 TeV recorded by the ATLAS experiment at the LHC in 2012. The search was done in the context of the next-to-minimal supersymmetric standard model, in which the new particles are the lightest neutral pseudoscalar Higgs bosons (). One of the two bosons is required to decay to two muons while the other is required to decay to two -leptons. No significant excess is observed above the expected backgrounds in the dimuon invariant mass range from 3.7 GeV to 50 GeV. Upper limits are placed on the production of relative to the Standard Model production, assuming no coupling of the boson to quarks. The most stringent limit is placed at 3.5\% for 3.75 GeV. Upper limits are also placed on the production cross section of from 2.33 pb to 0.72 pb, for fixed = 5 GeV with ranging from 100 GeV to 500 GeV
