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Mårtensson, Mikael U. F.ORCID iD iconorcid.org/0000-0002-7288-3610
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Publications (10 of 414) Show all publications
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2023). Combination of searches for invisible decays of the Higgs boson using 139 fb-1 of proton-proton collision data at root s=13 TeV collected with the ATLAS experiment. Physics Letters B, 842, Article ID 137963.
Open this publication in new window or tab >>Combination of searches for invisible decays of the Higgs boson using 139 fb-1 of proton-proton collision data at root s=13 TeV collected with the ATLAS experiment
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2023 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 842, article id 137963Article in journal (Refereed) Published
Abstract [en]

Many extensions of the Standard Model predict the production of dark matter particles at the LHC. Sufficiently light dark matter particles may be produced in decays of the Higgs boson that would appear invisible to the detector. This Letter presents a statistical combination of searches for H & RARR; invisible decays where multiple production modes of the Standard Model Higgs boson are considered. These searches are performed with the ATLAS detector using 139 fb-1 of proton-proton collisions at a centre-of-mass energy of & RADIC;s = 13 TeV at the LHC. In combination with the results at & RADIC;s = 7 TeV and 8 TeV, an upper limit on the H & RARR; invisible branching ratio of 0.107 (0.077) at the 95% confidence level is observed (expected). These results are also interpreted in the context of models where the 125 GeV Higgs boson acts as a portal to dark matter, and limits are set on the scattering cross-section of weakly interacting massive particles and nucleons.

Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-512132 (URN)10.1016/j.physletb.2023.137963 (DOI)001023908100001 ()
Funder
CERNEU, European Research CouncilKnut and Alice Wallenberg Foundation
Note

For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2023.137963

Available from: 2023-09-25 Created: 2023-09-25 Last updated: 2023-09-25Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2023). Determination of the strong coupling constant from transverse energy-energy correlations in multijet events at √ s=13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP) (7), Article ID 085.
Open this publication in new window or tab >>Determination of the strong coupling constant from transverse energy-energy correlations in multijet events at √ s=13 TeV with the ATLAS detector
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2023 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 7, article id 085Article in journal (Refereed) Published
Abstract [en]

Measurements of transverse energy-energy correlations and their associated azimuthal asymmetries in multijet events are presented. The analysis is performed using a data sample corresponding to 139 fb(-1) of proton-proton collisions at a centre-of-mass energy of root s = 13TeV, collected with the ATLAS detector at the Large Hadron Collider. The measurements are presented in bins of the scalar sum of the transverse momenta of the two leading jets and unfolded to particle level. They are then compared to next-to-next-to-leading-order perturbative QCD calculations for the first time, which feature a significant reduction in the theoretical uncertainties estimated using variations of the renormalisation and factorisation scales. The agreement between data and theory is good, thus providing a precision test of QCD at large momentum transfers Q. The strong coupling constant alpha(s) is extracted as a function of Q, showing a good agreement with the renormalisation group equation and with previous analyses. A simultaneous fit to all transverse energy-energy correlation distributions across different kinematic regions yields a value of alpha(s)( mZ) = 0.1175 +/- 0.0006 (exp.)(+0.0034) (-0.0017) (theo.), while the global fit to the asymmetry distributions yields alpha(s)(m(Z)) = 0.1185 +/- 0.0009 (exp.)(+0.0025)(-0.0012)(theo.).

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Hadron-Hadron Scattering, Jet Physics, Jets
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-514955 (URN)10.1007/JHEP07(2023)085 (DOI)001061751900001 ()
Note

For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)085

Available from: 2023-10-24 Created: 2023-10-24 Last updated: 2023-10-24Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2023). Inclusive-photon production and its dependence on photon isolation in pp collisions at √s=13 TeV using 139 fb-1 of ATLAS data. Journal of High Energy Physics (JHEP) (7), Article ID 086.
Open this publication in new window or tab >>Inclusive-photon production and its dependence on photon isolation in pp collisions at √s=13 TeV using 139 fb-1 of ATLAS data
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2023 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 7, article id 086Article in journal (Refereed) Published
Abstract [en]

Measurements of differential cross sections are presented for inclusive isolated photon production in pp collisions at a centre-of-mass energy of 13TeV provided by the LHC and using 139 fb(-1) of data recorded by the ATLAS experiment. The cross sections are measured as functions of the photon transverse energy in different regions of photon pseudorapidity. The photons are required to be isolated by means of a fixed-cone method with two different cone radii. The dependence of the inclusive-photon production on the photon isolation is investigated by measuring the fiducial cross sections as functions of the isolation-cone radius and the ratios of the differential cross sections with different radii in different regions of photon pseudorapidity. The results presented in this paper constitute an improvement with respect to those published by ATLAS earlier: the measurements are provided for different isolation radii and with a more granular segmentation in photon pseudorapidity that can be exploited in improving the determination of the proton parton distribution functions. These improvements provide a more in-depth test of the theoretical predictions. Next-to-leading-order QCD predictions from JETPHOX and SHERPA and next-to-next-to-leading-order QCD predictions from NNLOJET are compared to the measurements, using several parameterisations of the proton parton distribution functions. The measured cross sections are well described by the fixed-order QCD predictions within the experimental and theoretical uncertainties in most of the investigated phase-space region.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Hadron-Hadron Scattering
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-514299 (URN)10.1007/JHEP07(2023)086 (DOI)001062449200001 ()
Funder
CERNEU, European Research Council
Note

For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)086

Available from: 2023-10-17 Created: 2023-10-17 Last updated: 2023-10-17Bibliographically approved
Camplani, A., Dittmeier, S., Annovi, A., Axiotis, K., Beccherle, R., Biesuz, N., . . . Zinsser, J. (2023). Intel Stratix 10 FPGA design for track reconstruction for the ATLAS experiment at the HL-LHC. Journal of Instrumentation, 18(6), Article ID P06029.
Open this publication in new window or tab >>Intel Stratix 10 FPGA design for track reconstruction for the ATLAS experiment at the HL-LHC
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2023 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 18, no 6, article id P06029Article in journal (Refereed) Published
Abstract [en]

The fast reconstruction of charged particle tracks with high efficiency and track quality is an essential part of the online data selection for the ATLAS experiment at the High Luminosity LHC. Dedicated custom designed hardware boards and software simulations have been developed to assess the feasibility of a Hardware Tracking Trigger (HTT) system. The Pattern Recognition Mezzanine (PRM), as part of the HTT system, has been designed to recognize track candidates in silicon detectors with Associative Memory ASICs and to select and reconstruct tracks using linearized algorithms implemented in an Intel Stratix 10 MX FPGA. The highly parallelized FPGA design makes extensive use of the integrated High-Bandwidth-Memory.In this paper, the FPGA design for the PRM board is presented. Its functionalities have been verified in both simulations and hardware tests on an Intel Stratix 10 MX development kit.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2023
Keywords
Online farms and online filtering, Pattern recognition, cluster finding, calibration and fitting methods, Trigger algorithms, Trigger concepts and systems (hardware and software)
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-519553 (URN)10.1088/1748-0221/18/06/P06029 (DOI)001122927700001 ()
Available from: 2024-01-09 Created: 2024-01-09 Last updated: 2024-01-09Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2023). Measurement of cross sections for production of a Z boson in association with a flavor-inclusive or doubly b-tagged large-radius jet in proton-proton collisions at √s=13  TeV with the ATLAS experiment. Physical Review D: covering particles, fields, gravitation, and cosmology, 108(1), Article ID 012022.
Open this publication in new window or tab >>Measurement of cross sections for production of a Z boson in association with a flavor-inclusive or doubly b-tagged large-radius jet in proton-proton collisions at √s=13  TeV with the ATLAS experiment
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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 1, article id 012022Article in journal (Refereed) Published
Abstract [en]

We present measurements of cross sections for production of a leptonically decaying Z boson in association with a large-radius jet in 13 TeV proton-proton collisions at the LHC, using 36  fb−1 of data from the ATLAS detector. Integrated and differential cross sections are measured at particle level in both a flavor inclusive and a doubly b-tagged fiducial phase space. The large-radius jet mass and transverse momentum, its kinematic relationship to the Z boson, and the angular separation of b-tagged small-radius track jets within the large-radius jet are measured. This measurement constitutes an important test of perturbative quantum chromodynamics in kinematic and flavor configurations relevant to several Higgs boson and beyond-Standard-Model physics analyses. The results highlight issues with modeling of additional hadronic activity in the flavor-inclusive selection, and a distinction between flavor-number schemes in the b-tagged phase space.

Place, publisher, year, edition, pages
American Physical Society, 2023
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-516029 (URN)10.1103/PhysRevD.108.012022 (DOI)001055270000001 ()
Funder
Swedish Research CouncilEU, European Research CouncilEU, Horizon 2020Australian Research CouncilCERNDanish National Research FoundationThe Research Council of NorwayWallenberg FoundationsEuropean Regional Development Fund (ERDF)German Research Foundation (DFG)
Note

For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.012022

Title in Web of Science: Measurement of cross sections for production of a Z boson in association with a flavor-inclusive or doubly b-tagged large-radius jet in proton-proton collisions at p s=13 TeV with the ATLAS experiment

Available from: 2023-11-17 Created: 2023-11-17 Last updated: 2023-11-17Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2023). Measurement of the CP properties of Higgs boson interactions with tau-leptons with the ATLAS detector. European Physical Journal C, 83, Article ID 563.
Open this publication in new window or tab >>Measurement of the CP properties of Higgs boson interactions with tau-leptons with the ATLAS detector
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2023 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 83, article id 563Article in journal (Refereed) Published
Abstract [en]

A study of the charge conjugation and parity (CP) properties of the interaction between the Higgs boson and tau -leptons is presented. The study is based on a measurement of CP-sensitive angular observables defined by the visible decay products of t -leptons produced in Higgs boson decays. The analysis uses 139 fb(-1) of proton-proton collision data recorded at a centre-of-mass energy of root s = 13 TeV with the ATLAS detector at the Large Hadron Collider. Contributions from CP-violating interactions between the Higgs boson and t -leptons are described by a single mixing angle parameter phi(tau) in the generalised Yukawa interaction. Without constraining the H -> tau tau signal strength to its expected value under the Standard Model hypothesis, the mixing angle ft is measured to be 9 degrees +/- 16 degrees, with an expected value of 0 degrees +/- 28 degrees at the 68% confidence level. The pure CPodd hypothesis is disfavoured at a level of 3.4 standard deviations. The results are compatible with the predictions for the Higgs boson in the Standard Model.

Place, publisher, year, edition, pages
Springer, 2023
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-515713 (URN)10.1140/epjc/s10052-023-11583-y (DOI)001062395800002 ()
Funder
EU, European Research CouncilEU, Horizon 2020Swedish Research CouncilCERNGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologyKnut and Alice Wallenberg Foundation
Note

For complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-023-11583-y

Available from: 2023-11-09 Created: 2023-11-09 Last updated: 2023-11-09Bibliographically approved
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
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2023). Measurement of the production of a W boson in association with a charmed hadron in pp collisions at root s=13 TeV with the ATLAS detector. Physical Review D: covering particles, fields, gravitation, and cosmology, 108(3), Article ID 032012.
Open this publication in new window or tab >>Measurement of the production of a W boson in association with a charmed hadron in pp collisions at root s=13 TeV with the ATLAS detector
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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 032012Article in journal (Refereed) Published
Abstract [en]

The production of a W boson in association with a single charm quark is studied using 140 fb(-1) of vS = 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. ffiffis The charm quark is tagged by the presence of a charmed hadron reconstructed with a secondary-vertex fit. The W boson is reconstructed from the decay to either an electron or a muon and the missing transverse momentum present in the event. The charmed mesons reconstructed are D+ ?K-p+p+ and D*+ ? D0p+ ? (K-p+)p+ and the charge conjugate decays in the fiducial regions where pT(e; mu) > 30 GeV, l?(e; mu)l < 2.5, pT(D(*)) > 8 GeV, and l?(D(*))l < 2.2. The integrated and normalized differential cross sections as a function of the pseudorapidity of the lepton from the W boson decay, and of the transverse momentum of the charmed hadron, are extracted from the data using a profile likelihood fit. The measured total fiducial cross sections are sfidOS-SS(W- + D+) = 50.2 + 0.2(stat)+2.4 -2.3(syst) pb, s(OS-SS) (fid)(W- + D+) = 48.5 + 0.2(stat)+2.3-2.2(syst) pb, sfidOS-SS(W- + D*+) = 51.1 + 0.4(stat)+1.9 -1.8 (syst) pb, and s(OS-SS) (fid)(W+ + D*-) = 50.0 + 0.4(stat)+1.9 -1.8 (syst) pb. Results are compared with the predictions of next-to-leading-order quantum chromodynamics calculations performed using state-of-the-art parton distribution functions. Additionally, the ratio of charm to anticharm production cross sections is studied to probe the s -s- quark asymmetry. The ratio is found to be R+ c = 0.971 + 0.006(stat) + 0.011(syst). The ratio and cross-section measurements are consistent with the predictions obtained with parton distribution function sets that have a symmetric s -s- sea, indicating that any s -s- asymmetry in the Bjorken-x region relevant for this measurement is small.

Place, publisher, year, edition, pages
American Physical Society, 2023
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-515712 (URN)10.1103/PhysRevD.108.032012 (DOI)001069542700001 ()
Funder
CERNSwedish Research CouncilEU, European Research CouncilEU, Horizon 2020Göran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologyKnut and Alice Wallenberg Foundation
Note

For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.032012

Available from: 2023-11-09 Created: 2023-11-09 Last updated: 2023-11-09Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2023). Measurement of the properties of Higgs boson production at √s=13 TeV in the H→ γγ channel using 139 fb-1 of pp collision data with the ATLAS experiment. Journal of High Energy Physics (JHEP) (7), Article ID 088.
Open this publication in new window or tab >>Measurement of the properties of Higgs boson production at √s=13 TeV in the H→ γγ channel using 139 fb-1 of pp collision data with the ATLAS experiment
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2023 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 7, article id 088Article in journal (Refereed) Published
Abstract [en]

Measurements of Higgs boson production cross-sections are carried out in the diphoton decay channel using 139 fb(-1) of pp collision data at root s = 13TeV collected by the ATLAS experiment at the LHC. The analysis is based on the definition of 101 distinct signal regions using machine-learning techniques. The inclusive Higgs boson signal strength in the diphoton channel is measured to be 1.04(+0.10) (-0.09). Cross-sections for gluon-gluon fusion, vector-boson fusion, associated production with a W or Z boson, and top associated production processes are reported. An upper limit of 10 times the Standard Model prediction is set for the associated production process of a Higgs boson with a single top quark, which has a unique sensitivity to the sign of the top quark Yukawa coupling. Higgs boson production is further characterized through measurements of Simplified Template Cross-Sections (STXS). In total, cross-sections of 28 STXS regions are measured. The measured STXS cross-sections are compatible with their Standard Model predictions, with a p-value of 93%. The measurements are also used to set constraints on Higgs boson coupling strengths, as well as on new interactions beyond the Standard Model in an effective field theory approach. No significant deviations from the Standard Model predictions are observed in these measurements, which provide significant sensitivity improvements compared to the previous ATLAS results.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Hadron-Hadron Scattering, Higgs Physics
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-514954 (URN)10.1007/JHEP07(2023)088 (DOI)001061751900002 ()
Note

For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)088

Available from: 2023-10-24 Created: 2023-10-24 Last updated: 2023-10-24Bibliographically approved
Aad, G., Asimakopoulou, E. M., Bergeås Kuutmann, E., Bokan, P., Brenner, R., Ekelöf, T., . . . Zwalinski, L. (2023). Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at root s=13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP), Article ID 19.
Open this publication in new window or tab >>Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at root s=13 TeV with the ATLAS detector
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2023 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, article id 19Article in journal (Refereed) Published
Abstract [en]

A measurement of the top-quark mass (m(t)) in the t (t) over bar -> lepton+ jets channel is presented, with an experimental technique which exploits semileptonic decays of b-hadrons produced in the top-quark decay chain. The distribution of the invariant mass m(l mu) of the lepton, l (with l = e, mu), from the W-boson decay and the muon, mu, originating from the b-hadron decay is reconstructed, and a binned-template profile likelihood fit is performed to extract mt. The measurement is based on data corresponding to an integrated luminosity of 36.1 fb(-1) of root s = 13 TeV pp collisions provided by the Large Hadron Collider and recorded by the ATLAS detector. The measured value of the top-quark mass is mt = 174.41 +/- 0.39 (stat.) +/- 0.66 (syst.) +/- 0.25 (recoil) GeV, where the third uncertainty arises from changing the Pythia8 parton shower gluon-recoil scheme, used in top-quark decays, to a recently developed setup.

Place, publisher, year, edition, pages
Springer, 2023
Keywords
Hadron-Hadron Scattering, Top Physics
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-512323 (URN)10.1007/JHEP06(2023)019 (DOI)001035480600001 ()
Funder
EU, European Research CouncilEU, Horizon 2020Swedish Research CouncilCERNKnut and Alice Wallenberg FoundationGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of Technology
Note

For complete list of authors see http://dx.doi.org/10.1007/JHEP06(2023)019

Available from: 2023-09-25 Created: 2023-09-25 Last updated: 2023-09-25Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-7288-3610

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