Change search
Link to record
Permanent link

Direct link
BETA
Alternative names
Publications (10 of 809) Show all publications
Aaboud, M., Kastanas, K. A., Lund-Jensen, B., Sidebo, P. E., Strandberg, J., Zwalinski, L. & et al., . (2017). Electron efficiency measurements with the ATLAS detector using 2012 LHC proton-proton collision data. European Physical Journal C, 77(3), Article ID 195.
Open this publication in new window or tab >>Electron efficiency measurements with the ATLAS detector using 2012 LHC proton-proton collision data
Show others...
2017 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 77, no 3, 195Article in journal (Refereed) Published
Abstract [en]

This paper describes the algorithms for the reconstruction and identification of electrons in the central region of the ATLAS detector at the Large Hadron Collider (LHC). These algorithms were used for all ATLAS results with electrons in the final state that are based on the 2012 pp collision data produced by the LHC at root s = 8 TeV. The efficiency of these algorithms, together with the charge misidentification rate, is measured in data and evaluated in simulated samples using electrons from Z -> ee, Z -> ee gamma and J/Psi -> ee decays. For these efficiency measurements, the full recorded data set, corresponding to an integrated luminosity of 20.3 fb(-1), is used. Based on a new reconstruction algorithm used in 2012, the electron reconstruction efficiency is 97% for electrons with E-T = 15 GeV and 99% at E-T = 50 GeV. Combining this with the efficiency of additional selection criteria to reject electrons from background processes or misidentified hadrons, the efficiency to reconstruct and identify electrons at the ATLAS experiment varies from 65 to 95%, depending on the transverse momentum of the electron and background rejection.

Place, publisher, year, edition, pages
Springer, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-210877 (URN)10.1140/epjc/s10052-017-4756-2 (DOI)000398956200005 ()28579919 (PubMedID)
Funder
Swedish Research CouncilEU, European Research CouncilEU, FP7, Seventh Framework ProgrammeEU, Horizon 2020
Note

QC 20170706

Available from: 2017-07-06 Created: 2017-07-06 Last updated: 2017-07-06Bibliographically approved
Jia, J. Y., Kastanas, K. A., Lund-Jensen, B., Ripellino, G., Sidebo, P. E., Strandberg, J., . . . et al., . (2017). Heavy Ion Results from ATLAS. Paper presented at 26th International Conference on Ultrarelativistic Nucleus-Nucleus Collissions (Quark Matter), FEB 05-11, 2017, Chicago, IL. Nuclear Physics A, 967, 51-58.
Open this publication in new window or tab >>Heavy Ion Results from ATLAS
Show others...
2017 (English)In: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 967, 51-58 p.Article in journal (Refereed) Published
Abstract [en]

These proceedings provide an overview of the new results obtained with the ATLAS detector at the LHC, which were presented in the Quark Matter 2017 conference. These results were covered by twelve parallel talks, one flash talk and eleven posters. These proceedings group these results into five areas: initial state, jet quenching, quarkonium production, longitudinal flow dynamics, and collectivity in small systems.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2017
Keyword
ATLAS, heavy-ion collisions, quark-gluon plasma, jet quenching, flow decorrelation, multi-particle cumulants
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-219864 (URN)10.1016/j.nuclphysa.2017.05.076 (DOI)000413384100008 ()2-s2.0-85032457630 (Scopus ID)
Conference
26th International Conference on Ultrarelativistic Nucleus-Nucleus Collissions (Quark Matter), FEB 05-11, 2017, Chicago, IL
Note

QC 20171213

Available from: 2017-12-13 Created: 2017-12-13 Last updated: 2017-12-13Bibliographically approved
Aaboud, M., Kastanas, K. A., Lund-Jensen, B., Sidebo, P. E., Strandberg, J., Zwalinski, L. & et. al., . (2017). High-E-T isolated-photon plus jets production in pp collisions at root s=8 TeV with the ATLAS detector. Nuclear Physics B, 918, 257-316.
Open this publication in new window or tab >>High-E-T isolated-photon plus jets production in pp collisions at root s=8 TeV with the ATLAS detector
Show others...
2017 (English)In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 918, 257-316 p.Article in journal (Refereed) Published
Abstract [en]

The dynamics of isolated-photon plus one-, two- and three-jet production in pp collisions at a centre-of-mass energy of 8 TeV are studied with the ATLAS detector at the LHC using a data set with an integrated luminosity of 20.2 fb(-1). Measurements of isolated-photon plus jets cross sections are presented as functions of the photon and jet transverse momenta. The cross sections as functions of the azimuthal angle between the photon and the jets, the azimuthal angle between the jets, the photon-jet invariant mass and the scattering angle in the photon-jet centre-of-mass system are presented. The pattern of QCD radiation around the photon and the leading jet is investigated by measuring jet production in an annular region centred on each object; enhancements are observed around the leading jet with respect to the photon in the directions towards the beams. The experimental measurements are compared to several different theoretical calculations, and overall a good description of the data is found. (C) 2017 The Author(s). Published by Elsevier B.V.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-209327 (URN)10.1016/j.nuclphysb.2017.03.006 (DOI)000401097200012 ()2-s2.0-85016126339 (Scopus ID)
Note

QC 20170619

Available from: 2017-06-19 Created: 2017-06-19 Last updated: 2017-06-19Bibliographically approved
Aaboud, M., Kastanas, K. A., Lund-Jensen, B., Sidebo, P. E., Strandberg, J., Zwalinski, L. & et al., . (2017). High-E-T isolated-photon plus jets production in pp collisions at root s=8 TeV with the ATLAS detector. Nuclear Physics B, 918, 257-316.
Open this publication in new window or tab >>High-E-T isolated-photon plus jets production in pp collisions at root s=8 TeV with the ATLAS detector
Show others...
2017 (English)In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, ISSN 0550-3213, Vol. 918, 257-316 p.Article in journal (Refereed) Published
Abstract [en]

The dynamics of isolated-photon plus one-, two- and three-jet production in pp collisions at a centre-of-mass energy of 8 TeV are studied with the ATLAS detector at the LHC using a data set with an integrated luminosity of 20.2 fb(-1). Measurements of isolated-photon plus jets cross sections are presented as functions of the photon and jet transverse momenta. The cross sections as functions of the azimuthal angle between the photon and the jets, the azimuthal angle between the jets, the photon-jet invariant mass and the scattering angle in the photon-jet centre-of-mass system are presented. The pattern of QCD radiation around the photon and the leading jet is investigated by measuring jet production in an annular region centred on each object; enhancements are observed around the leading jet with respect to the photon in the directions towards the beams. The experimental measurements are compared to several different theoretical calculations, and overall a good description of the data is found.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-209405 (URN)10.1016/j.nuclphysb.2017.03.006 (DOI)000401097200012 ()
Note

QC 2017-06-19

Available from: 2017-06-19 Created: 2017-06-19 Last updated: 2017-06-19Bibliographically approved
Aaboud, M., Lund-Jensen, B., Ripellino, G., Sidebo, P. E., Strandberg, J., L. Zwalinski, . & et. al., . (2017). Identification and rejection of pile-up jets at high pseudorapidity with the ATLAS detector. European Physical Journal C, 77(9), Article ID 580.
Open this publication in new window or tab >>Identification and rejection of pile-up jets at high pseudorapidity with the ATLAS detector
Show others...
2017 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 77, no 9, 580Article in journal (Refereed) Published
Abstract [en]

The rejection of forward jets originating from additional proton–proton interactions (pile-up) is crucial for a variety of physics analyses at the LHC, including Standard Model measurements and searches for physics beyond the Standard Model. The identification of such jets is challenging due to the lack of track and vertex information in the pseudorapidity range | η| > 2.5. This paper presents a novel strategy for forward pile-up jet tagging that exploits jet shapes and topological jet correlations in pile-up interactions. Measurements of the per-jet tagging efficiency are presented using a data set of 3.2 fb- 1 of proton–proton collisions at a centre-of-mass energy of 13 TeV collected with the ATLAS detector. The fraction of pile-up jets rejected in the range 2.5 < | η| < 4.5 is estimated in simulated events with an average of 22 interactions per bunch-crossing. It increases with jet transverse momentum and, for jets with transverse momentum between 20 and 50 GeV, it ranges between 49% and 67% with an efficiency of 85% for selecting hard-scatter jets. A case study is performed in Higgs boson production via the vector-boson fusion process, showing that these techniques mitigate the background growth due to additional proton–proton interactions, thus enhancing the reach for such signatures.

Place, publisher, year, edition, pages
Springer, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-218269 (URN)10.1140/epjc/s10052-017-5081-5 (DOI)000409355300002 ()2-s2.0-85028970999 (Scopus ID)
Note

QC 20171124

Available from: 2017-11-24 Created: 2017-11-24 Last updated: 2017-11-24Bibliographically approved
Aaboud, M., Kastanas, K. A., Lund-Jensen, B., Ripellino, G., Sidebo, P. E., Strandberg, J., . . . et al., . (2017). Identification and rejection of pile-up jets at high pseudorapidity with the ATLAS detector (vol 77, 580, 2017). European Physical Journal C, 77(10), Article ID 712.
Open this publication in new window or tab >>Identification and rejection of pile-up jets at high pseudorapidity with the ATLAS detector (vol 77, 580, 2017)
Show others...
2017 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 77, no 10, 712Article in journal (Refereed) Published
Place, publisher, year, edition, pages
SPRINGER, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-219862 (URN)10.1140/epjc/s10052-017-5245-3 (DOI)000413947700003 ()2-s2.0-85032573545 (Scopus ID)
Note

QC 20171213

Available from: 2017-12-13 Created: 2017-12-13 Last updated: 2017-12-13Bibliographically approved
Aaboud, M., Kastanas, K. A., Lund-Jensen, B., Sidebo, P. E., Strandberg, J., Zwalinski, L. & et al., . (2017). Jet reconstruction and performance using particle flow with the ATLAS Detector. European journal of physics, 77(7), Article ID 466.
Open this publication in new window or tab >>Jet reconstruction and performance using particle flow with the ATLAS Detector
Show others...
2017 (English)In: European journal of physics, ISSN 0143-0807, E-ISSN 1361-6404, Vol. 77, no 7, 466Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-212286 (URN)10.1140/epjc/s10052-017-5031-2 (DOI)000405437300002 ()2-s2.0-85024369614 (Scopus ID)
Note

QC 20170817

Available from: 2017-08-17 Created: 2017-08-17 Last updated: 2017-08-17Bibliographically approved
Aaboud, M., Kastanas, K. A., Lund-Jensen, B., Ripellino, G., Sidebo, P. E., Strandberg, J., . . . et al., . (2017). Measurement of b-hadron pair production with the ATLAS detector in proton-proton collisions at root s=8 TeV. Journal of High Energy Physics (JHEP) (11), Article ID 062.
Open this publication in new window or tab >>Measurement of b-hadron pair production with the ATLAS detector in proton-proton collisions at root s=8 TeV
Show others...
2017 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 11, 062Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Springer, 2017
Keyword
B physics, Hadron-Hadron scattering (experiments)
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-219412 (URN)10.1007/JHEP11(2017)062 (DOI)000415197700001 ()
Note

QC 20171205

Available from: 2017-12-05 Created: 2017-12-05 Last updated: 2017-12-05Bibliographically approved
Aaboud, M., Kastanas, K. A., Lund-Jensen, B., Ripellino, G., Sidebo, P. E., Strandberg, J., . . . et al., . (2017). 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. European Physical Journal C, 77(11), Article ID 765.
Open this publication in new window or tab >>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
Show others...
2017 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 77, no 11, 765Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Springer, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-219625 (URN)10.1140/epjc/s10052-017-5315-6 (DOI)000415376100001 ()2-s2.0-85035324811 (Scopus ID)
Note

QC 20171211

Available from: 2017-12-11 Created: 2017-12-11 Last updated: 2017-12-11Bibliographically approved
Aaboud, M., Lund-Jensen, B., Sidebo, P. E., Strandberg, J., Zwalinski, L. & et al., . (2017). 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. European Physical Journal C (7), Article ID 490.
Open this publication in new window or tab >>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
Show others...
2017 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, no 7, 490Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Springer, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-219740 (URN)10.1140/epjc/s10052-017-5004-5 (DOI)000406426400001 ()2-s2.0-85026307625 (Scopus ID)
Note

QC 20171211

Available from: 2017-12-11 Created: 2017-12-11 Last updated: 2017-12-11Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8913-0981

Search in DiVA

Show all publications