143069
CERN/FIS-NUC/0005/2015
FCT - Fundação para a Ciência e a Tecnologia, I.P.
Portugal
3599-PPCDT
400,000.00 €
2015-03-01
2017-02-28
The number of charged particles inside jets is a widely used discriminant for identifying the quark or gluon nature of the initiating parton and is sensitive to both the perturbative and non-perturbative components of fragmentation. This paper presents a measurement of the average number of charged particles with pT>500MeV inside high-momentum jets in dijet events using 20.3 fb−1 of data recorded with the ATLAS...
A search for highly ionizing particles produced in proton-proton collisions at 8 TeV center-of-mass energy is performed by the ATLAS Collaboration at the CERN Large Hadron Collider. The data set used corresponds to an integrated luminosity of 7.0 fb−1. A customized trigger significantly increases the sensitivity, permitting a search for such particles with charges and energies beyond what was previously access...
The distribution of particles inside hadronic jets produced in the decay of boosted W and Z bosons can be used to discriminate such jets from the continuum background. Given that a jet has been identified as likely resulting from the hadronic decay of a boosted W or Z boson, this paper presents a technique for further differentiating Z bosons from W bosons. The variables used are jet mass, jet charge, and a b-t...
A search for the standard model Higgs boson produced in association with a vector boson with the decay H→ττ is presented. The data correspond to 20.3 fb−1 of integrated luminosity from proton-proton collisions at s√=8 TeV recorded by the ATLAS experiment at the LHC during 2012. The data agree with the background expectation, and 95% confidence-level upper limits are placed on the cross section of this process...
A search with the ATLAS detector is presented for the Standard Model Higgs boson produced by vector-boson fusion and decaying to a pair of bottom quarks, using 20.2 fb−1 of LHC proton-proton collision data at s√=8 TeV. The signal is searched for as a resonance in the invariant mass distribution of a pair of jets containing b-hadrons in vector-boson-fusion candidate events. The yield is measured to be −0.8 ± 2.3...
The production of Z bosons with one or two isolated high-energy photons is studied using pp collisions at s√=8 TeV. The analyses use a data sample with an integrated luminosity of 20.3 fb−1 collected by the ATLAS detector during the 2012 LHC data taking. The Zγ and Zγγ production cross sections are measured with leptonic (e+e−, μ+μ−, νν¯) decays of the Z boson, in extended fiducial regions defined in terms of...
Measurements of normalized differential cross sections of top quark pair (t¯t) production are presented as a function of the mass, the transverse momentum and the rapidity of the t¯t system in proton-proton collisions at center-of-mass energies of √s=7 and 8 TeV. The data set corresponds to an integrated luminosity of 4.6 fb−1 at 7 TeV and 20.2 fb−1 at 8 TeV, recorded with the ATLAS detector at the Large Hadr...
This paper presents studies of the performance of several jet-substructure techniques, which are used to identify hadronically decaying top quarks with high transverse momentum contained in large-radius jets. The efficiency of identifying top quarks is measured using a sample of top-quark pairs and the rate of wrongly identifying jets from other quarks or gluons as top quarks is measured using multijet events c...
The performance of the jet trigger for the ATLAS detector at the LHC during the 2011 data taking period is described. During 2011 the LHC provided proton–proton collisions with a centre-of-mass energy of 7 TeV and heavy ion collisions with a 2.76 TeV per nucleon–nucleon collision energy. The ATLAS trigger is a three level system designed to reduce the rate of events from the 40 MHz nominal maximum bunch crossin...
A 6.8 nb−1 sample of pp collision data collected under low-luminosity conditions at View the MathML sources=7TeV by the ATLAS detector at the Large Hadron Collider is used to study diffractive dijet production. Events containing at least two jets with View the MathML sourcepT>20GeV are selected and analysed in terms of variables which discriminate between diffractive and non-diffractive processes. Cross section...
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