| 211. |
- Abulaiti, Yiming, et al.
(författare)
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Jet energy scale measurements and their systematic uncertainties in proton-proton collisions at root s=13 TeV with the ATLAS detector
- 2017
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 96:7
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Tidskriftsartikel (refereegranskat)abstract
- Jet energy scale measurements and their systematic uncertainties are reported for jets measured with the ATLAS detector using proton-proton collision data with a center-of-mass energy of root s = 13 TeV, corresponding to an integrated luminosity of 3.2 fb(-1) collected during 2015 at the LHC. Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells, using the anti-k(t) algorithm with radius parameter R = 0.4. Jets are calibrated with a series of simulation-based corrections and in situ techniques. In situ techniques exploit the transverse momentum balance between a jet and a reference object such as a photon, Z boson, or multijet system for jets with 20 < p(T) < 2000 GeV and pseudorapidities of vertical bar eta vertical bar < 4.5, using both data and simulation. An uncertainty in the jet energy scale of less than 1% is found in the central calorimeter region (vertical bar eta vertical bar < 1.2) for jets with 100 < p(T) < 500 GeV. An uncertainty of about 4.5% is found for low-p(T) jets with p(T) = 20 GeV in the central region, dominated by uncertainties in the corrections for multiple proton-proton interactions. The calibration of forward jets (vertical bar eta vertical bar > 0.8) is derived from dijet p(T) balance measurements. For jets of p(T) = 80 GeV, the additional uncertainty for the forward jet calibration reaches its largest value of about 2% in the range vertical bar eta vertical bar > 3.5 and in a narrow slice of 2.2 < vertical bar eta vertical bar < 2.4.
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| 212. |
- Abulaiti, Yiming, et al.
(författare)
-
Jet reconstruction and performance using particle flow with the ATLAS Detector
- 2017
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052 .- 0143-0807 .- 1361-6404. ; 77:7
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the implementation and performance of a particle flow algorithm applied to 20.2 fb(-1) of ATLAS data from 8 TeV proton-proton collisions in Run 1 of the LHC. The algorithm removes calorimeter energy deposits due to charged hadrons from consideration during jet reconstruction, instead using measurements of their momenta from the inner tracker. This improves the accuracy of the charged-hadron measurement, while retaining the calorimeter measurements of neutral-particle energies. The paper places emphasis on how this is achieved, while minimising double-counting of charged-hadron signals between the inner tracker and calorimeter. The performance of particle flow jets, formed from the ensemble of signals from the calorimeter and the inner tracker, is compared to that of jets reconstructed from calorimeter energy deposits alone, demonstrating improvements in resolution and pile-up stability.
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| 213. |
- Abulaiti, Yiming, et al.
(författare)
-
Luminosity determination in pp collisions at root s=8 TeV using the ATLAS detector at the LHC
- 2016
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 76:12
-
Tidskriftsartikel (refereegranskat)abstract
- The luminosity determination for the ATLAS detector at the LHC during pp collisions at root s = 8 TeV in 2012 is presented. The evaluation of the luminosity scale is performed using several luminometers, and comparisons between these luminosity detectors are made to assess the accuracy, consistency and long-term stability of the results. A luminosity uncertainty of delta L/L = +/- 1.9% is obtained for the 22.7 fb(-1) of pp collision data delivered to ATLAS at root s = 8 TeV in 2012.
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| 214. |
- Abulaiti, Yiming, et al.
(författare)
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Measurement of b-hadron pair production with the ATLAS detector in proton-proton collisions at root s=8 TeV
- 2017
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :11
-
Tidskriftsartikel (refereegranskat)abstract
- A measurement of b-hadron pair production is presented, based on a data set corresponding to an integrated luminosity of 11.4 fb(-1) of proton-proton collisions recorded at root s = 8TeV with the ATLAS detector at the LHC. Events are selected in which a b-hadron is reconstructed in a decay channel containing J = psi -> mu mu, and a second b-hadron is reconstructed in a decay channel containing a muon. Results are presented in a fiducial volume de fined by kinematic requirements on three muons based on those used in the analysis. The fiducial cross section is measured to be 17.7 +/- 0.1(stat.) +/- 2.0(syst.) nb. A number of normalised differential cross sections are also measured, and compared to predictions from the PYTHIA8, HERWIG++, MADGRAPH5_AMC@NLO+PYTHIA8 and SHERPA event generators, providing new constraints on heavy flavour production.
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| 215. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of charged-particle distributions sensitive to the underlying event in root s=13 TeV proton-proton collisions with the ATLAS detector at the LHC
- 2017
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :3
-
Tidskriftsartikel (refereegranskat)abstract
- We present charged-particle distributions sensitive to the underlying event, measured by the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13 TeV, in low-luminosity Large Hadron Collider fills corresponding to an integrated luminosity of 1.6 nb-1. The distributions were constructed using charged particles with absolute pseudorapidity less than 2.5 and with transverse momentum greater than 500 MeV, in events with at least one such charged particle with transverse momentum above 1 GeV. These distributions characterise the angular distribution of energy and particle flows with respect to the charged particle with highest transverse momentum, as a function of both that momentum and of charged-particle multiplicity. The results have been corrected for detector effects and are compared to the predictions of various Monte Carlo event generators, experimentally establishing the level of underlying-event activity at LHC Run 2 energies and providing inputs for the development of event generator modelling. The current models in use for UE modelling typically describe this data to 5% accuracy, compared with data uncertainties of less than 1%.
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| 216. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of D-*+/-, D-+/- and D-S(+/-) meson production cross sections in pp collisions at root s=7 TeV with the ATLAS detector
- 2016
-
Ingår i: Nuclear Physics B. - : Elsevier BV. - 0550-3213 .- 1873-1562. ; 907, s. 717-763
-
Tidskriftsartikel (refereegranskat)abstract
- The production of D*(+/-), D-+/- and D-S(+/-) charmed mesons has been measured with the ATLAS detector in pp collisions at,/7s = 7 TeV at the LHC, using data corresponding to an integrated luminosity of 280 nb(-)1(.) The charmed mesons have been reconstructed in the range of transverse momentum 3.5 < p(T)(D) < 100 GeV and pseudorapidity vertical bar eta(D)vertical bar < 2.1. The differential cross sections as a function of transverse momentum and pseudorapidity were measured for D*(+/-) and D-+/- production. The next-to-leading-order QCD predictions are consistent with the data in the visible kinematic region within the large theoretical uncertainties. Using the visible D cross sections and an extrapolation to the full kinematic phase space, the strangeness -suppression factor in charm fragmentation, the fraction of charged non -strange D mesons produced in a vector state, and the total cross section of charm production at root s = 7 TeV were derived.
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| 217. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of detector-corrected observables sensitive to the anomalous production of events with jets and large missing transverse momentum in pp collisions at root s=13 TeV using the ATLAS detector
- 2017
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:11
-
Tidskriftsartikel (refereegranskat)abstract
- Observables sensitive to the anomalous production of events containing hadronic jets and missing momentum in the plane transverse to the proton beams at the Large Hadron Collider are presented. The observables are defined as a ratio of cross sections, for events containing jets and large missing transverse momentum to events containing jets and a pair of charged leptons from the decay of a Z/gamma* boson. This definition minimises experimental and theoretical systematic uncertainties in the measurements. This ratio is measured differentially with respect to a number of kinematic properties of the hadronic system in two phase-space regions; one inclusive single-jet region and one region sensitive to vector-boson-fusion topologies. The data are found to be in agreement with the Standard Model predictions and used to constrain a variety of theoretical models for dark-matter production, including simplified models, effective field theory models, and invisible decays of the Higgs boson. The measurements use 3.2 fb(-1) of proton-proton collision data recorded by the ATLAS experiment at a centre-of-mass energy of 13TeV and are fully corrected for detector effects, meaning that the data can be used to constrain new-physics models beyond those shown in this paper.
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| 218. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of differential cross sections and W+/W- cross-section ratios for W boson production in association with jets at root s=8 TeV with the ATLAS detector
- 2018
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer-Verlag New York. - 1126-6708 .- 1029-8479. ; :5
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a measurement of the W boson production cross section and the W+/W- cross-section ratio, both in association with jets, in proton-proton collisions at root s = 8 TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is performed in final states containing one electron and missing transverse momentum using data corresponding to an integrated luminosity of 20.2 fb(-1). Differential cross sections for events with at least one or two jets are presented for a range of observables, including jet transverse momenta and rapidities, the scalar sum of transverse momenta of the visible particles and the missing transverse momentum in the event, and the transverse momentum of the W boson. For a subset of the observables, the differential cross sections of positively and negatively charged W bosons are measured separately. In the cross-section ratio of W+/W- the dominant systematic uncertainties cancel out, improving the measurement precision by up to a factor of nine. The observables and ratios selected for this paper provide valuable input for the up quark, down quark, and gluon parton distribution functions of the proton.
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| 219. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of dijet azimuthal decorrelations in pp collisions at root s=8 TeV with the ATLAS detector and determination of the strong coupling
- 2018
-
Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 98:9
-
Tidskriftsartikel (refereegranskat)abstract
- A measurement of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations is presented, using the quantity R-Delta phi. The quantity R-Delta phi specifies the fraction of the inclusive dijet events in which the azimuthal opening angle of the two jets with the highest transverse momenta is less than a given value of the parameter Delta phi(max). The quantity R-Delta phi is measured in proton-proton collisions at root s = 8 TeV as a function of the dijet rapidity interval, the event total scalar transverse momentum, and Delta phi(max). The measurement uses an event sample corresponding to an integrated luminosity of 20.2 fb(-1) collected with the ATLAS detector at the CERN Large Hadron Collider. Predictions of a perturbative QCD calculation at next-to-leading order in the strong coupling with corrections for nonperturbative effects are compared to the data. The theoretical predictions describe the data in the whole kinematic region. The data are used to determine the strong coupling alpha(S) and to study its running for momentum transfers from 260 GeV to above 1.6 TeV. Analysis that combines data at all momentum transfers results in alpha(S) (m(Z)) = 0.1127(- 0.0027) (+0.0063).
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| 220. |
- Abulaiti, Yiming, et al.
(författare)
-
Measurement of event-shape observables in Z -> l(+)l(-) events in pp collisions at root s=7 TeV with the ATLAS detector at the LHC
- 2016
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 76:7
-
Tidskriftsartikel (refereegranskat)abstract
- Event-shape observables measured using charged particles in inclusive Z-boson events are presented, using the electron and muon decay modes of the Z bosons. The measurements are based on an integrated luminosity of 1.1 fb(-1) of proton-proton collisions recorded by the ATLAS detector at the LHC at a centre-of-mass energy root s = 7 TeV. Charged-particle distributions, excluding the lepton-antilepton pair from the Z-boson decay, are measured in different ranges of transverse momentum of the Z boson. Distributions include multiplicity, scalar sum of transverse momenta, beam thrust, transverse thrust, spherocity, and F-parameter, which are in particular sensitive to properties of the underlying event at small values of the Z-boson transverse momentum. The measured observables are compared with predictions from PYTHIA 8, Sherpa, and HERWIG 7. Typically, all three Monte Carlo generators provide predictions that are in better agreement with the data at high Z-boson transverse momenta than at low Z-boson transverse momenta, and for the observables that are less sensitive to the number of charged particles in the event.
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