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Gradin, P. O. Joakim
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Publications (10 of 414) Show all publications
Aaboud, M., Asimakopoulou, E. M., Bergeås Kuutmann, E., Brenner, R., Ekelöf, T., Ellajosyula, V., . . . Zwalinski, L. (2023). Measurement of the inclusive t¯t production cross section in the lepton + jets channel in pp collisions at √s =7  TeV with the ATLAS detector using support vector machines. Physical Review D: covering particles, fields, gravitation, and cosmology, 108(3), Article ID 032014.
Open this publication in new window or tab >>Measurement of the inclusive t¯t production cross section in the lepton + jets channel in pp collisions at √s =7  TeV with the ATLAS detector using support vector machines
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2023 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 108, no 3, article id 032014Article in journal (Refereed) Published
Abstract [en]

A measurement of the top quark pair-production cross section in the lepton+jets decay channel is presented. It is based on 4.6  fb−1 of √s=7  TeV pp collision data collected during 2011 by the ATLAS experiment at the CERN Large Hadron Collider. A three-class, multidimensional event classifier based on support vector machines is used to differentiate t¯t events from backgrounds. The t¯t production cross section is found to be σt¯t = 168.5±0.7(stat) +6.2−5.9(syst) +3.4−3.2(lumi)  pb. The result is consistent with the Standard Model prediction based on QCD calculations at next-to-next-to-leading order.

Place, publisher, year, edition, pages
American Physical Society, 2023
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-516031 (URN)10.1103/PhysRevD.108.032014 (DOI)001063420300001 ()
Funder
Swedish Research CouncilEU, European Research CouncilAustralian Research CouncilDanish National Research FoundationThe Research Council of NorwayWallenberg FoundationsEuropean Regional Development Fund (ERDF)EU, Horizon 2020German Research Foundation (DFG)
Note

For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.032014

Title in Web of Science: Measurement of the inclusive t(t)over-bar production cross section in the lepton plus jets channel in pp collisions at √s=7 TeV with the ATLAS detector using support vector machines

Available from: 2023-11-16 Created: 2023-11-16 Last updated: 2023-11-16Bibliographically approved
Aaboud, M., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2021). A search for the dimuon decay of the Standard Model Higgs boson with the ATLAS detector. Physics Letters B, 812, Article ID 135980.
Open this publication in new window or tab >>A search for the dimuon decay of the Standard Model Higgs boson with the ATLAS detector
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2021 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 812, article id 135980Article in journal (Refereed) Published
Abstract [en]

A search for the dimuon decay of the Standard Model (SM) Higgs boson is performed using data corresponding to an integrated luminosity of 139 fb(-1) collected with the ATLAS detector in Run 2 pp collisions at root s = 13 TeV at the Large Hadron Collider. The observed (expected) significance over the background-only hypothesis for a Higgs boson with a mass of 125.09 GeV is 2.0 sigma (1.7 sigma). The observed upper limit on the cross section times branching ratio for pp -> H -> mu mu is 2.2 times the SM prediction at 95% confidence level, while the expected limit on a H -> mu mu signal assuming the absence (presence) of a SM signal is 1.1(2.0). The best-fit value of the signal strength parameter, defined as the ratio of the observed signal yield to the one expected in the SM, is mu = 1.2 +/- 0.6.

Place, publisher, year, edition, pages
ElsevierELSEVIER, 2021
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-435206 (URN)10.1016/j.physletb.2020.135980 (DOI)000608167600020 ()
Funder
CERNSwedish Research CouncilEU, European Research CouncilEU, Horizon 2020Wallenberg Foundations
Note

For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2020.135980

Available from: 2021-02-26 Created: 2021-02-26 Last updated: 2024-01-15Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2021). Differential cross-section measurements for the electroweak production of dijets in association with a Z boson in proton-proton collisions at ATLAS. European Physical Journal C, 81(2), Article ID 163.
Open this publication in new window or tab >>Differential cross-section measurements for the electroweak production of dijets in association with a Z boson in proton-proton collisions at ATLAS
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2021 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 81, no 2, article id 163Article in journal (Refereed) Published
Abstract [en]

Differential cross-sectionmeasurements are presented for the electroweak production of two jets in association with a Z boson. These measurements are sensitive to the vector-boson fusion production mechanism and provide a fundamental test of the gauge structure of the Standard Model. The analysis is performed using proton-proton collision data collected by ATLAS at root s = 13 TeV and with an integrated luminosity of 139 fb(-1). The differential cross-sections are measured in the Z -> l(+)l(-) decay channel (l = e, mu) as a function of four observables: the dijet invariant mass, the rapidity interval spanned by the two jets, the signed azimuthal angle between the two jets, and the transverse momentum of the dilepton pair. The data are corrected for the effects of detector inefficiency and resolution and are sufficiently precise to distinguish between different state-of-the-art theoretical predictions calculated using Powheg+Pythia8, Herwig7+Vbfnlo and Sherpa 2.2. The differential cross-sections are used to search for anomalous weak-boson self-interactions using a dimension-six effective field theory. Themeasurement of the signed azimuthal angle between the two jets is found to be particularly sensitive to the interference between the Standard-Model and dimension-six scattering amplitudes and provides a direct test of charge-conjugation and parity invariance in the weak-boson self-interactions.

Place, publisher, year, edition, pages
Springer NatureSPRINGER, 2021
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-441003 (URN)10.1140/epjc/s10052-020-08734-w (DOI)000620538400001 ()
Funder
CERNSwedish Research CouncilEU, European Research CouncilEU, Horizon 2020Wallenberg Foundations
Note

For complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-020-08734-w

Available from: 2021-04-26 Created: 2021-04-26 Last updated: 2024-01-15Bibliographically approved
Aaboud, M., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2021). Measurement of hadronic event shapes in high-p(T) multijet final states at √s=13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP) (1), Article ID 188.
Open this publication in new window or tab >>Measurement of hadronic event shapes in high-p(T) multijet final states at √s=13 TeV with the ATLAS detector
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2021 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 1, article id 188Article in journal (Refereed) Published
Abstract [en]

A measurement of event-shape variables in proton-proton collisions at large momentum transfer is presented using data collected at root s = 13 TeV with the ATLAS detector at the Large Hadron Collider. Six event-shape variables calculated using hadronic jets are studied in inclusive multijet events using data corresponding to an integrated luminosity of 139 fb(-1). Measurements are performed in bins of jet multiplicity and in different ranges of the scalar sum of the transverse momenta of the two leading jets, reaching scales beyond 2 TeV. These measurements are compared with predictions from Monte Carlo event generators containing leading-order or next-to-leading order matrix elements matched to parton showers simulated to leading-logarithm accuracy. At low jet multiplicities, shape discrepancies between the measurements and the Monte Carlo predictions are observed. At high jet multiplicities, the shapes are better described but discrepancies in the normalisation are observed.

Place, publisher, year, edition, pages
Springer NatureSPRINGER, 2021
Keywords
Hadron-Hadron scattering (experiments)
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-440053 (URN)10.1007/JHEP01(2021)188 (DOI)000613473000001 ()
Funder
CERNSwedish Research CouncilEU, European Research CouncilEU, Horizon 2020
Note

Correction in: Journal of High Energy Physics, Issue 12, Article number 53, DOI 10.1007/JHEP12(2021)053For complete list of authors see http://dx.doi.org/10.1007/JHEP01(2021)188

Available from: 2021-04-14 Created: 2021-04-14 Last updated: 2024-01-15Bibliographically approved
Aaboud, M., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2021). Measurement of the associated production of a Higgs boson decaying into b-quarks with a vector boson at high transverse momentum in pp collisions at √s=13 TeV with the ATLAS detector. Physics Letters B, 816, Article ID 136204.
Open this publication in new window or tab >>Measurement of the associated production of a Higgs boson decaying into b-quarks with a vector boson at high transverse momentum in pp collisions at √s=13 TeV with the ATLAS detector
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2021 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 816, article id 136204Article in journal (Refereed) Published
Abstract [en]

The associated production of a Higgs boson with a W or Z boson decaying into leptons and where the Higgs boson decays to a b (b) over bar pair is measured in the high vector-boson transverse momentum regime, above 250 GeV, with the ATLAS detector. The analysed data, corresponding to an integrated luminosity of 139 fb(-1), were collected in proton-proton collisions at the Large Hadron Collider between 2015 and 2018 at a centre-of-mass energy of root s = 13 TeV. The measured signal strength, defined as the ratio of the measured signal yield to that predicted by the Standard Model, is 0.72(-0.36)(+0.39) corresponding to an observed (expected) significance of 2.1 (2.7) standard deviations. Cross-sections of associated production of a Higgs boson decaying into b quark pairs with a W or Z gauge boson, decaying into leptons, are measured in two exclusive vector boson transverse momentum regions, 250-400 GeV and above 400 GeV, and interpreted as constraints on anomalous couplings in the framework of a Standard Model effective field theory.

Place, publisher, year, edition, pages
ElsevierElsevier BV, 2021
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-443486 (URN)10.1016/j.physletb.2021.136204 (DOI)000647421500036 ()
Funder
CERNSwedish Research CouncilEU, European Research CouncilEU, Horizon 2020
Note

For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2021.136204

Available from: 2021-06-01 Created: 2021-06-01 Last updated: 2024-01-15Bibliographically approved
Aaboud, M., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2021). Measurement of the jet mass in high transverse momentum Z(-> b(b)over-bar)gamma production at root s=13 TeV using the ATLAS detector. Physics Letters B, 812, Article ID 135991.
Open this publication in new window or tab >>Measurement of the jet mass in high transverse momentum Z(-> b(b)over-bar)gamma production at root s=13 TeV using the ATLAS detector
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2021 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 812, article id 135991Article in journal (Refereed) Published
Abstract [en]

The integrated fiducial cross-section and unfolded differential jet mass spectrum of high transverse momentum Z -> b (b) over bar decays are measured in Z gamma events in proton-proton collisions at root s = 13 TeV. The data analysed were collected between 2015 and 2016 with the ATLAS detector at the Large Hadron Collider and correspond to an integrated luminosity of 36.1 fb(-1). Photons are required to have a transverse momentum p(T) > 175 GeV. The Z -> b (b) over bar decay is reconstructed using a jet with p(T) > 200 GeV, found with the anti-k(t) R = 1.0 jet algorithm, and groomed to remove soft and wide-angle radiation and to mitigate contributions from the underlying event and additional proton-proton collisions. Two different but related measurements are performed using two jet grooming definitions for reconstructing the Z -> b (b) over bar decay: trimming and soft drop. These algorithms differ in their experimental and phenomenological implications regarding jet mass reconstruction and theoretical precision. To identify Zbosons, b-tagged R = 0.2 track-jets matched to the groomed large-R calorimeter jet are used as a proxy for the b-quarks. The signal yield is determined from fits of the data-driven background templates to the different jet mass distributions for the two grooming methods. Integrated fiducial cross-sections and unfolded jet mass spectra for each grooming method are compared with leading-order theoretical predictions. The results are found to be in good agreement with Standard Model expectations within the current statistical and systematic uncertainties.

Place, publisher, year, edition, pages
ElsevierELSEVIER, 2021
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-435205 (URN)10.1016/j.physletb.2020.135991 (DOI)000608167600013 ()
Funder
Swedish Research CouncilEU, Horizon 2020CERNEU, European Research CouncilGöran Gustafsson Foundation for Research in Natural Sciences and MedicineWallenberg Foundations
Note

For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2020.135991

Available from: 2021-02-26 Created: 2021-02-26 Last updated: 2024-01-15Bibliographically approved
Aaboud, M., Asimakopoulou, E. M., Bergeås Kuutmann, E., Brenner, R., Ekelöf, T., Ellajosyula, V., . . . Zwalinski, L. (2021). Measurement of the relative B-c(+/-)/B-+/- production cross section with the ATLAS detector at root s=8 TeV. Physical Review D: covering particles, fields, gravitation, and cosmology, 104(1), Article ID 012010.
Open this publication in new window or tab >>Measurement of the relative B-c(+/-)/B-+/- production cross section with the ATLAS detector at root s=8 TeV
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2021 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 104, no 1, article id 012010Article in journal (Refereed) Published
Abstract [en]

The total cross section and differential cross sections for the production of B-c(+/-) mesons, times their branching fraction to J/psi pi(+/-), are measured relative to those for the production of B-+/- mesons, times their branching fraction to J/psi K-+/-. The data used for this study correspond to an integrated luminosity of 20.3 fb(-1) of pp collisions recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a center-of-mass energy of root s = 8 TeV. The measurement is performed differentially in bins of transverse momentum p(T) for 13 GeV < p(T)(B-c(+/-)) < 22 GeV and p(T)(B-c(+/-)) > 22 GeV and in bins of rapidity y for vertical bar y vertical bar < 0.75 and 0.75 < vertical bar y vertical bar < 2.3. The relative cross section times branching fraction for the full range p(T) > 13 GeV and vertical bar y vertical bar < 2.3 is (0.34 +/- 0.04(stat) (+0.06)(-0.02 sys) +/- 0.01(lifetime))%. The differential measurements suggest that the production cross section of the B-c(+/-) decreases faster with p(T) than the production cross section of the B-+/-, while no significant dependence on rapidity is observed.

Place, publisher, year, edition, pages
American Physical SocietyAMER PHYSICAL SOC, 2021
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-451020 (URN)10.1103/PhysRevD.104.012010 (DOI)000679144000001 ()
Funder
CERNSwedish Research CouncilEU, European Research Council
Note

For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.104.012010

Available from: 2021-08-27 Created: 2021-08-27 Last updated: 2024-01-15Bibliographically approved
Aaboud, M., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2021). Measurements of top-quark pair single- and double-differential cross-sections in the all-hadronic channel in pp collisions at root s=13 TeV using the ATLAS detector. Journal of High Energy Physics (JHEP), Article ID 33.
Open this publication in new window or tab >>Measurements of top-quark pair single- and double-differential cross-sections in the all-hadronic channel in pp collisions at root s=13 TeV using the ATLAS detector
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2021 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, article id 33Article in journal (Refereed) Published
Abstract [en]

Differential cross-sections are measured for top-quark pair production in the all-hadronic decay mode, using proton-proton collision events collected by the ATLAS experiment in which all six decay jets are separately resolved. Absolute and normalised single- and double-differential cross-sections are measured at particle and parton level as a function of various kinematic variables. Emphasis is placed on well-measured observables in fully reconstructed final states, as well as on the study of correlations between the top-quark pair system and additional jet radiation identified in the event. The study is performed using data from proton-proton collisions at root s = 13 TeV collected by the ATLAS detector at CERN's Large Hadron Collider in 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb(-1). The rapidities of the individual top quarks and of the top-quark pair are well modelled by several independent event generators. Significant mismodelling is observed in the transverse momenta of the leading three jet emissions, while the leading top-quark transverse momentum and top-quark pair transverse momentum are both found to be incompatible with several theoretical predictions.

Place, publisher, year, edition, pages
Springer NatureSPRINGER, 2021
Keywords
Hadron-Hadron scattering (experiments), Top physics
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-434450 (URN)10.1007/JHEP01(2021)033 (DOI)000607134800001 ()
Funder
CERNSwedish Research CouncilEU, European Research CouncilEU, Horizon 2020Wallenberg Foundations
Note

For complete list of authors see http://dx.doi.org/10.1007/JHEP01(2021)033

Available from: 2021-02-12 Created: 2021-02-12 Last updated: 2024-01-15Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2021). Measurements of WH and ZH production in the H -> bb decay channel in pp collisions at 13Te with the ATLAS detector. European Physical Journal C, 81(2), Article ID 178.
Open this publication in new window or tab >>Measurements of WH and ZH production in the H -> bb decay channel in pp collisions at 13Te with the ATLAS detector
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2021 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 81, no 2, article id 178Article in journal (Refereed) Published
Abstract [en]

Measurements of the Standard Model Higgs boson decaying into a bb¯bb¯ pair and produced in association with a W or Z boson decaying into leptons, using proton–proton collision data collected between 2015 and 2018 by the ATLAS detector, are presented. The measurements use collisions produced by the Large Hadron Collider at a centre-of-mass energy of s√=13TeVs=13TeV, corresponding to an integrated luminosity of 139fb−1139fb−1. The production of a Higgs boson in association with a W or Z boson is established with observed (expected) significances of 4.0 (4.1) and 5.3 (5.1) standard deviations, respectively. Cross-sections of associated production of a Higgs boson decaying into bottom quark pairs with an electroweak gauge boson, W or Z, decaying into leptons are measured as a function of the gauge boson transverse momentum in kinematic fiducial volumes. The cross-section measurements are all consistent with the Standard Model expectations, and the total uncertainties vary from 30% in the high gauge boson transverse momentum regions to 85% in the low regions. Limits are subsequently set on the parameters of an effective Lagrangian sensitive to modifications of the WH and ZH processes as well as the Higgs boson decay into bb¯bb¯.

Place, publisher, year, edition, pages
Springer NatureSPRINGER, 2021
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-441004 (URN)10.1140/epjc/s10052-020-08677-2 (DOI)000623088700004 ()
Funder
CERNSwedish Research CouncilEU, European Research CouncilEU, Horizon 2020Wallenberg FoundationsGöran Gustafsson Foundation for Research in Natural Sciences and Medicine
Note

For complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-020-08677-2

Available from: 2021-04-26 Created: 2021-04-26 Last updated: 2024-01-15Bibliographically approved
Aaboud, M., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2021). Observation of photon-induced W+ W- production in pp collisions at √s=13 TeV using the ATLAS detector. Physics Letters B, 816, Article ID 136190.
Open this publication in new window or tab >>Observation of photon-induced W+ W- production in pp collisions at √s=13 TeV using the ATLAS detector
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2021 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 816, article id 136190Article in journal (Refereed) Published
Abstract [en]

This letter reports the observation of photon-induced production of W-boson pairs, gamma gamma -> WW. The analysis uses 139 fb(-1) of LHC proton-proton collision data taken at root s = 13 TeV recorded by the ATLAS experiment during the years 2015-2018. The measurement is performed selecting one electron and one muon, corresponding to the decay of the diboson system as WW -> e(+/-)nu mu(-/+)nu final state. The background-only hypothesis is rejected with a significance of well above 5 standard deviations consistent with the expectation from Monte Carlo simulation. A cross section for the gamma gamma -> WW process of 3.13 +/- 0.31(stat.) +/- 0.28(syst.) fb is measured in a fiducial volume close to the acceptance of the detector, by requiring an electron and a muon of opposite signs with large dilepton transverse momentum and exactly zero additional charged particles. This is found to be in agreement with the Standard Model prediction.

Place, publisher, year, edition, pages
ElsevierElsevier BV, 2021
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-443487 (URN)10.1016/j.physletb.2021.136190 (DOI)000647421500033 ()
Funder
CERNSwedish Research CouncilEU, European Research CouncilEU, Horizon 2020
Note

For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2021.136190

Available from: 2021-05-31 Created: 2021-05-31 Last updated: 2024-01-15Bibliographically approved
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