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Publications (10 of 10) Show all publications
Aad, G., Jovicevic, J., Kuwertz, E., Lund-Jensen, B., Morley, A., Strandberg, J., . . . et al., . (2016). Addendum to 'Measurement of the t (t)over-bar production cross-section using e mu events with b-tagged jets in pp collisions at root s = 7 and 8 TeV with the ATLAS detector'. European Physical Journal C, 76(11), Article ID 642.
Open this publication in new window or tab >>Addendum to 'Measurement of the t (t)over-bar production cross-section using e mu events with b-tagged jets in pp collisions at root s = 7 and 8 TeV with the ATLAS detector'
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2016 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, no 11, article id 642Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Springer, 2016
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-204415 (URN)10.1140/epjc/s10052-016-4501-2 (DOI)000394382800002 ()
Note

QC 20170324

Available from: 2017-03-24 Created: 2017-03-24 Last updated: 2019-12-04Bibliographically approved
Aad, G., Jovicevic, J., Kuwertz, E., Lund-Jensen, B., Morley, A. K., Strandberg, J. & Zwalinski, L. (2015). Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at root s = 8 TeV with the ATLAS detector (vol 75, 299, 2015). European Physical Journal C, 75(9), Article ID 408.
Open this publication in new window or tab >>Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at root s = 8 TeV with the ATLAS detector (vol 75, 299, 2015)
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2015 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 75, no 9, article id 408Article in journal (Refereed) Published
Place, publisher, year, edition, pages
SPRINGER, 2015
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-243655 (URN)10.1140/epjc/s10052-015-3639-7 (DOI)000363330800008 ()2-s2.0-84941127967 (Scopus ID)
Note

QC 20190205

Available from: 2019-02-05 Created: 2019-02-05 Last updated: 2019-12-19Bibliographically approved
Aad, G., Jovicevic, J., Kuwertz, E., Lund-Jensen, B., Strandberg, J., Zwalinski, L. & et al., . (2013). Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in root s=7 TeV pp collisions with the ATLAS detector. Physics Letters B, 718(3), 841-859
Open this publication in new window or tab >>Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in root s=7 TeV pp collisions with the ATLAS detector
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2013 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 718, no 3, p. 841-859Article in journal (Refereed) Published
Abstract [en]

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb(-1) of root s = 7 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results.

Place, publisher, year, edition, pages
Elsevier, 2013
Keywords
Supergauge Transformations, Parton Distributions, Supersymmetry, Particle, Model, Generators, Currents, Masses, States, Pions
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-119512 (URN)10.1016/j.physletb.2012.11.039 (DOI)000314259500014 ()2-s2.0-85042048821 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20130315. Author count: 2890

Available from: 2013-03-15 Created: 2013-03-15 Last updated: 2018-12-05Bibliographically approved
Aad, G., Jovicevic, J., Lund-Jensen, B., Strandberg, J., Zwalinski, L. & et al., . (2013). Search for pair production of heavy top-like quarks decaying to a high-p(T) W boson and a b quark in the lepton plus jets final state at root s=7 TeV with the ATLAS detector. Physics Letters B, 718(4-5), 1284-1302
Open this publication in new window or tab >>Search for pair production of heavy top-like quarks decaying to a high-p(T) W boson and a b quark in the lepton plus jets final state at root s=7 TeV with the ATLAS detector
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2013 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 718, no 4-5, p. 1284-1302Article in journal (Refereed) Published
Abstract [en]

A search is presented for production of a heavy up-type quark (t') together with its antiparticle, assuming a significant branching ratio for subsequent decay into a W boson and a b quark. The search is based on 4.7 fb(-1) of pp collisions root s = 7 TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in the lepton + jets final state, characterized by a high-transverse-momentum isolated electron or muon, large missing transverse momentum and at least three jets. The analysis strategy relies on the substantial boost of the W bosons in the t'(t') over bar signal when m(t') greater than or similar to 400 GeV. No significant excess of events above the Standard Model expectation is observed and the result of the search is interpreted in the context of fourth-generation and vector-like quark models. Under the assumption of a branching ratio BR(t' -> W b) = I, a fourth-generation t' quark with mass lower than 656 GeV is excluded at 95% confidence level. In addition, in light of the recent discovery of a new boson of mass similar to 126 GeV at the LHC, upper limits are derived in the two-dimensional plane of BR(t' -> Wb) versus BR(t' -> Ht), where H is the Standard Model Higgs boson, for vector-like quarks of various masses.

Keywords
Production Cross-Section, Higgs-Boson, Parton Distributions, Hadronic Collisions, Matrix-Elements, Standard Model, Pp Collisions, Mass, Lhc, Channel
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-121977 (URN)10.1016/j.physletb.2012.11.071 (DOI)000314554300014 ()2-s2.0-84872486617 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20130507. Author count: 2905

Available from: 2013-05-07 Created: 2013-05-07 Last updated: 2019-12-04Bibliographically approved
Aad, G., Jovicevic, J., Kuwertz, E., Lund-Jensen, B., Strandberg, J., Zwalinski, L. & et al., . (2012). Evidence for the associated production of a W boson and a top quark in ATLAS at root s=7 TeV. Physics Letters B, 716(1), 142-159
Open this publication in new window or tab >>Evidence for the associated production of a W boson and a top quark in ATLAS at root s=7 TeV
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2012 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 716, no 1, p. 142-159Article in journal (Refereed) Published
Abstract [en]

This Letter presents evidence for the associated production of a W boson and a top quark using 2.05 fb(-1) of pp collision data at root s = 7 TeV accumulated with the ATLAS detector at the LHC. The analysis is based on the selection of the dileptonic final states with events featuring two isolated leptons, electron or muon, with significant transverse missing momentum and at least one jet. An approach based on boosted decision trees has been developed to improve the discrimination of single top-quark Wt events from background. A template fit to the final classifier distributions is performed to determine the cross-section. The result is incompatible with the background-only hypothesis at the 3.3 sigma level, the expected sensitivity assuming the Standard Model production rate being 3.4 sigma. The corresponding cross-section is determined and found to be sigma(wt) = 16.8 +/- 2.9 (stat) +/- 4.9 (syst) pb, in good agreement with the Standard Model expectation. From this result the CKM matrix element vertical bar V-tb vertical bar = 1.03(-0.19)(+0.16) is derived assuming that the Wt production through vertical bar V-ts vertical bar and vertical bar V-td vertical bar is small.

Keywords
ATLAS, Top quark, W plus t, Single top-quark
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-109525 (URN)10.1016/j.physletb.2012.08.011 (DOI)000309621400007 ()2-s2.0-85042037870 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20130107. Author count: 2868

Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2018-05-17Bibliographically approved
Aad, G., Jovicevic, J., Kuwertz, E., Lund-Jensen, B., Strandberg, J., Zwalinski, L. & et al., . (2012). Measurement of the t-channel single top-quark production cross section in pp collisions at root s=7 TeV with the ATLAS detector. Physics Letters B, 717(4-5), 330-350
Open this publication in new window or tab >>Measurement of the t-channel single top-quark production cross section in pp collisions at root s=7 TeV with the ATLAS detector
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2012 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 717, no 4-5, p. 330-350Article in journal (Refereed) Published
Abstract [en]

We report a measurement of the cross section of single top-quark production in the t-channel using 1.04 fb(-1) of pp collision data at root s = 7 TeV recorded with the ATLAS detector at the LHC. Selected events feature one electron or muon, missing transverse momentum, and two or three jets, exactly one of them identified as originating from a b quark. The cross section is measured by fitting the distribution of a multivariate discriminant constructed with a neural network, yielding sigma(t) = 83 +/- 4 (stat.)(-19)(+20) (syst.) pb, which is in good agreement with the prediction of the Standard Model. Using the ratio of the measured to the theoretically predicted cross section and assuming that the top-quark-related CKM matrix elements obey the relation vertical bar V-tb vertical bar >> vertical bar V-ts vertical bar, vertical bar V-td vertical bar, the coupling strength at the W-t-b vertex is determined to be vertical bar V-tb vertical bar = 1.13(-0.13)(+0.14). If it is assumed that vertical bar V-tb vertical bar <= 1 a lower limit of vertical bar V-tb vertical bar > 0.75 is obtained at the 95% confidence level.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-107211 (URN)10.1016/j.physletb.2012.09.031 (DOI)000310863300008 ()2-s2.0-85041779750 (Scopus ID)
Note

QC 20121210. Author count: 3051

Available from: 2012-12-10 Created: 2012-12-10 Last updated: 2018-05-17Bibliographically approved
Aad, G., Jovicevic, J., Kuwertz, E., Lund-Jensen, B., Strandberg, J., Zwalinski, L. & et al., . (2012). Measurement of W gamma and Z gamma production cross sections in pp collisions at root s=7 TeV and limits on anomalous triple gauge couplings with the ATLAS detector. Physics Letters B, 717(1-3), 49-69
Open this publication in new window or tab >>Measurement of W gamma and Z gamma production cross sections in pp collisions at root s=7 TeV and limits on anomalous triple gauge couplings with the ATLAS detector
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2012 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 717, no 1-3, p. 49-69Article in journal (Refereed) Published
Abstract [en]

This Letter presents measurements of l(+/-) nu gamma and l(+)l(-)gamma (l = e.mu) production in 1.02 fb(-1) of pp collision data recorded at root s = 7 TeV with the ATLAS detector at the LHC in the first half of 2011. Events dominated by W gamma and Z gamma production with leptonic decays of the W and Z bosons are selected, and their production cross sections and kinematic properties are measured in several ranges of the photon transverse energy. The results are compared to Standard Model predictions and are used to determine limits on anomalous WW gamma and ZZ gamma/Z gamma gamma couplings.

Keywords
Boson Sector
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-107153 (URN)10.1016/j.physletb.2012.09.017 (DOI)000310187700007 ()2-s2.0-85042002951 (Scopus ID)
Note

QC 20121206. Author count: 2888

Available from: 2012-12-06 Created: 2012-12-06 Last updated: 2018-05-17Bibliographically approved
Aad, G., Jovicevic, J., Kuwertz, E., Lund-Jensen, B., Strandberg, J., Zwalinski, L. & et al., . (2012). Search for a standard model Higgs boson in the H -> ZZ -> l(+)l(-) nu(nu)over-bar decay channel using 4.7 fb(-1) of root s=7 TeV data with the ATLAS detector. Physics Letters B, 717(1-3), 29-48
Open this publication in new window or tab >>Search for a standard model Higgs boson in the H -> ZZ -> l(+)l(-) nu(nu)over-bar decay channel using 4.7 fb(-1) of root s=7 TeV data with the ATLAS detector
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2012 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 717, no 1-3, p. 29-48Article in journal (Refereed) Published
Abstract [en]

A search for a Standard Model Higgs boson decaying via H -> ZZ -> l(+)l(-) nu(nu) over bar, where l represents electrons or muons, is presented. It is based on proton-proton collision data at root s = 7 TeV, collected by the ATLAS experiment at the LHC during 2011 and corresponding to an integrated luminosity of 4.7 fb(-1). The data agree with the expected Standard Model backgrounds. Upper limits on the Higgs boson production cross section are derived for Higgs boson masses between 200 GeV and 600 GeV and the production of a Standard Model Higgs boson with a mass in the range 319-558 GeV is excluded at the 95% confidence level.

Keywords
Standard Model Higgs Boson, ATLAS
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-107157 (URN)10.1016/j.physletb.2012.09.016 (DOI)000310187700006 ()2-s2.0-85042028646 (Scopus ID)
Note

QC 20121206. Author count: 2868

Available from: 2012-12-06 Created: 2012-12-06 Last updated: 2018-05-17Bibliographically approved
Aad, G., Jovicevic, J., Kuwertz, E., Lund-Jensen, B., Strandberg, J., Zwalinski, L. & et al., . (2012). Search for a Standard Model Higgs boson in the mass range 200-600 GeV in the H -> ZZ -> l(+)l(-)q(q)over-bar decay channel with the ATLAS detector. Physics Letters B, 717(1-3), 70-88
Open this publication in new window or tab >>Search for a Standard Model Higgs boson in the mass range 200-600 GeV in the H -> ZZ -> l(+)l(-)q(q)over-bar decay channel with the ATLAS detector
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2012 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 717, no 1-3, p. 70-88Article in journal (Refereed) Published
Abstract [en]

A search for a heavy Standard Model Higgs boson decaying via H -> ZZ -> l(+)l(-)q (q) over bar, where l = e or mu, is presented. The search uses a data set of pp collisions at root s = 7 TeV, corresponding to an integrated luminosity of 4.7 fb(-1) collected in 2011 by the ATLAS detector at the CERN LHC. No significant excess of events above the estimated background is found. Upper limits at 95% confidence level on the production cross section of a Higgs boson with a mass in the range between 200 and 600 GeV are derived. A Standard Model Higgs boson with a mass in the range 300 GeV <= m(H) 322 <= GeV or 353 GeV <= m(H) <= 410 GeV is excluded at 95% CL The corresponding expected exclusion range is 351 GeV <= m(H) <= 404 GeV at 95% CL.

Keywords
Standard Model Higgs boson, ATLAS
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-107148 (URN)10.1016/j.physletb.2012.09.020 (DOI)000310187700008 ()2-s2.0-85042489759 (Scopus ID)
Note

QC 20121206. Author count: 2865

Available from: 2012-12-06 Created: 2012-12-06 Last updated: 2018-05-17Bibliographically approved
Aad, G., Jovicevic, J., Kuwertz, E., Lund-Jensen, B., Zwalinski, L. & et al., . (2012). Search for the Standard Model Higgs boson in the H -> WW(*()) -> lvlv decay mode with 4.7 fb(-1) of ATLAS data at root s=7 TeV. Physics Letters B, 716(1), 62-81
Open this publication in new window or tab >>Search for the Standard Model Higgs boson in the H -> WW(*()) -> lvlv decay mode with 4.7 fb(-1) of ATLAS data at root s=7 TeV
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2012 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 716, no 1, p. 62-81Article in journal (Refereed) Published
Abstract [en]

A search for the Standard Model Higgs boson in the H -> WW(*()) -> lvlv (l = e.mu) decay mode is presented. The search is performed using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb(-1) at a centre-of-mass energy of 7 TeV collected during 2011 with the ATLAS detector at the Large Hadron Collider. No significant excess of events over the expected background is observed. An upper bound is placed on the Higgs boson production cross section as a function of its mass. A Standard Model Higgs boson with mass in the range between 133 GeV and 261 GeV is excluded at 95% confidence level, while the expected exclusion range is from 127 GeV to 233 GeV.

Keywords
ATLAS, LHC, Higgs, WW
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-109527 (URN)10.1016/j.physletb.2012.08.010 (DOI)000309621400003 ()2-s2.0-85042507243 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20130107. Author count: 2864

Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2018-05-17Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5650-4556

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