| 1. |
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| 3. |
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| 4. |
- Ayeni, O. R., et al.
(författare)
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Clinical and Radiographic Criteria Define "Acceptable" Surgical Correction of Hip Femoroacetabular Impingement Syndrome as Well as Postoperative Complications: An International Modified Delphi Study
- 2023
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Ingår i: Arthroscopy-the Journal of Arthroscopic and Related Surgery. - : Elsevier BV. - 0749-8063. ; 39:5, s. 1198-1210
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To develop recommendations for clinical and radiographic criteria to help define the "acceptable" surgical correction of femoroacetabular impingement syndrome (FAIS) and identify/define complications postoperatively. Methods: A 3-phase modified Delphi study was conducted involving a case-based survey; a Likert/multiple choice-based survey concerning radiographic and physical examination characteristics to help define FAIS correction, as well as the prevalence and definition of potential postoperative complications; and 2 consensus meetings. Results: Of the 75 experts invited, 54 completed the Phase I survey, 50 completed the Phase II survey (72% and 67% response rate), and 50 participated in the Phase III consensus meetings. For both typical and atypical (complex) cases, there was consensus that fluoroscopy with multiple views and dynamic hip assessment should be used intraoperatively (96% and 100%, respectively). For typical FAIS cases, the Expert Panel agreed that Dunn lateral and anteroposterior radiographs were the most important radiographs to evaluate the hip postoperatively (88%, consensus). When asked about evaluating the correction of cam impingement postoperatively, 87% voted that they use subjective evaluation of the "sphericity" of the femoral head. In the case of focal and global pincer-type FAIS, there was consensus that the reduction or elimination of the crossover sign (84%) and lateral center-edge angle (91%) were important to inform the extent of the FAIS correction. There was consensus for recommending further investigation at 6 months postoperatively if hip pain had increased/plateaued (92% agreed); that additional investigation and treatment should occur between 6 and 12 months (90% agreed); and that a reoperation may be recommended at 12 months or later following this investigation period (89% agreed). Conclusions: This consensus project identified the importance of using fluoroscopy and dynamic hip assessment intraoperatively; Dunn lateral and anteroposterior view radiographs postoperatively; evaluating the "sphericity" of the femoral head for cam-type correction and the use of dynamic hip assessment; reducing/eliminating the crossover sign for focal pincertype FAIS; evaluating the lateral center-edge angle for global pincer-type FAIS; and avoiding overcorrection of pincer-type FAIS. In cases in which postoperative hip pain increased/plateaued, further investigation and treatment is warranted between 6 and 12 months, and a reoperation may be recommended at a minimum of 12 months depending on the cause of the hip pain. Clinical Relevance: Hip arthroscopy surgeons have yet to reach a firm agreement on what constitutes an "acceptable" or "good" surgery radiographically and how they can achieve desired clinical outcomes. Although this was a comprehensive effort, more study is needed to determine therapeutic thresholds that can be universally applied.
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| 5. |
- Saevarsdottir, S., et al.
(författare)
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Multiomics analysis of rheumatoid arthritis yields sequence variants that have large effects on risk of the seropositive subset
- 2022
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 81:8
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To find causal genes for rheumatoid arthritis (RA) and its seropositive (RF and/or ACPA positive) and seronegative subsets. Methods We performed a genome-wide association study (GWAS) of 31 313 RA cases (68% seropositive) and similar to 1 million controls from Northwestern Europe. We searched for causal genes outside the HLA-locus through effect on coding, mRNA expression in several tissues and/or levels of plasma proteins (SomaScan) and did network analysis (Qiagen). Results We found 25 sequence variants for RA overall, 33 for seropositive and 2 for seronegative RA, altogether 37 sequence variants at 34 non-HLA loci, of which 15 are novel. Genomic, transcriptomic and proteomic analysis of these yielded 25 causal genes in seropositive RA and additional two overall. Most encode proteins in the network of interferon-alpha/beta and IL-12/23 that signal through the JAK/STAT-pathway. Highlighting those with largest effect on seropositive RA, a rare missense variant in STAT4 (rs140675301-A) that is independent of reported non-coding STAT4-variants, increases the risk of seropositive RA 2.27-fold (p=2.1x10(-9)), more than the rs2476601-A missense variant in PTPN22 (OR=1.59, p=1.3x10(-160)). STAT4 rs140675301-A replaces hydrophilic glutamic acid with hydrophobic valine (Glu128Val) in a conserved, surface-exposed loop. A stop-mutation (rs76428106-C) in FLT3 increases seropositive RA risk (OR=1.35, p=6.6x10(-11)). Independent missense variants in TYK2 (rs34536443-C, rs12720356-C, rs35018800-A, latter two novel) associate with decreased risk of seropositive RA (ORs=0.63-0.87, p=10(-9)-10(-27)) and decreased plasma levels of interferon-alpha/beta receptor 1 that signals through TYK2/JAK1/STAT4. Conclusion Sequence variants pointing to causal genes in the JAK/STAT pathway have largest effect on seropositive RA, while associations with seronegative RA remain scarce.
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| 6. |
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| 7. |
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| 8. |
- Jensen, E. A.M., et al.
(författare)
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Detailed study of the decay of 21Mg
- 2024
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Ingår i: European Physical Journal A. - 1434-601X .- 1434-6001. ; 60:7
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Tidskriftsartikel (refereegranskat)abstract
- Beta-delayed proton and gamma emission in the decay of 21Mg has been measured at ISOLDE, CERN with the ISOLDE Decay Station (IDS) set-up. The existing decay scheme is updated, in particular what concerns proton transitions to excited states in 20Ne. Signatures of interference in several parts of the spectrum are used to settle spin and parity assignments to highly excited states in 21Na. The previously reported βpα branch is confirmed. A half-life of 120.5(4) ms is extracted for 21Mg. The revised decay scheme is employed to test mirror symmetry in the decay and to extract the beta strength distribution of 21Mg that is compared with theory.
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| 9. |
- Riisager, K., et al.
(författare)
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Search for beta-delayed proton emission from 11 Be
- 2020
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 56:3
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Tidskriftsartikel (refereegranskat)abstract
- We report on an attempt to reproduce the observation of β--delayed proton emission from 11Be through detection of the final state nucleus 10Be with accelerator mass spectrometry. Twelve samples were collected at the ISOLDE facility at CERN at different separator settings, allowing tests of different sources of contamination to be carried out. The observed amounts of 10Be per collected 11Be rule out several contamination sources, but do not agree internally. Formation of BeH molecular ions in the ion source may explain our data, in which case an upper limit of the βp branching ratio of 2.2 × 10 - 6 can be derived.
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| 10. |
- Aad, G., et al.
(författare)
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Search for non-resonant Higgs boson pair production in the 2b+2ℓ+ETmiss final state in pp collisions at s = 13 TeV with the ATLAS detector
- 2024
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media Deutschland GmbH. - 1029-8479 .- 1126-6708. ; 2024:2
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Tidskriftsartikel (refereegranskat)abstract
- A search for non-resonant Higgs boson pair (HH) production is presented, in which one of the Higgs bosons decays to a b-quark pair (bb¯) and the other decays to WW*, ZZ*, or τ+τ−, with in each case a final state with ℓ+ℓ−+ neutrinos (ℓ = e, μ). The analysis targets separately the gluon-gluon fusion and vector boson fusion production modes. Data recorded by the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb−1, are used in this analysis. Events are selected to have exactly two b-tagged jets and two leptons with opposite electric charge and missing transverse momentum in the final state. These events are classified using multivariate analysis algorithms to separate the HH events from other Standard Model processes. No evidence of the signal is found. The observed (expected) upper limit on the cross-section for non-resonant Higgs boson pair production is determined to be 9.7 (16.2) times the Standard Model prediction at 95% confidence level. The Higgs boson self-interaction coupling parameter κλ and the quadrilinear coupling parameter κ2V are each separately constrained by this analysis to be within the ranges [−6.2, 13.3] and [−0.17, 2.4], respectively, at 95% confidence level, when all other parameters are fixed. © The Author(s) 2024.
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| 11. |
- Aad, G., et al.
(författare)
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Statistical Combination of ATLAS Run 2 Searches for Charginos and Neutralinos at the LHC
- 2024
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Ingår i: Physical Review Letters. - : American Physical Society. - 1079-7114 .- 0031-9007. ; 133:3
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Tidskriftsartikel (refereegranskat)abstract
- Statistical combinations of searches for charginos and neutralinos using various decay channels are performed using 139 fb^{-1} of pp collision data at sqrt[s]=13 TeV with the ATLAS detector at the Large Hadron Collider. Searches targeting pure-wino chargino pair production, pure-wino chargino-neutralino production, or Higgsino production decaying via standard model W, Z, or h bosons are combined to extend the mass reach to the produced supersymmetric particles by 30-100 GeV. The depth of the sensitivity of the original searches is also improved by the combinations, lowering the 95% C.L. cross-section upper limits by 15%-40%.
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| 12. |
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| 13. |
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| 14. |
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| 15. |
- Modvig, S, et al.
(författare)
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Value of flow cytometry for MRD-based relapse prediction in B-cell precursor ALL in a multicenter setting.
- 2021
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Ingår i: Leukemia. - : Springer Science and Business Media LLC. - 1476-5551 .- 0887-6924. ; 35, s. 1894-1906
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Tidskriftsartikel (refereegranskat)abstract
- PCR of TCR/Ig gene rearrangements is considered the method of choice for minimal residual disease (MRD) quantification in BCP-ALL, but flow cytometry analysis of leukemia-associated immunophenotypes (FCM-MRD) is faster and biologically more informative. FCM-MRD performed in 18 laboratories across seven countries was used for risk stratification of 1487 patients with BCP-ALL enrolled in the NOPHO ALL2008 protocol. When no informative FCM-marker was available, risk stratification was based on real-time quantitative PCR. An informative FCM-marker was found in 96.2% and only two patients (0.14%) had non-informative FCM and non-informative PCR-markers. The overall 5-year event-free survival was 86.1% with a cumulative incidence of relapse (CIR5y) of 9.5%. FCM-MRD levels on days 15 (HzR 4.0, p<0.0001), 29 (HzR 2.7, p<0.0001), and 79 (HzR 3.5, p<0.0001) associated with hazard of relapse adjusted for age, cytogenetics, and WBC. The early (day 15) response associated with CIR5y adjusted for day 29 FCM-MRD, with higher levels in adults (median 2.4×10-2 versus 5.2×10-3, p<0.0001). Undetectable FCM- and/or PCR-MRD on day 29 identified patients with a very good outcome (CIR5y=3.2%). For patients who did not undergo transplantation, day 79 FCM-MRD>10-4 associated with a CIR5y=22.1%. In conclusion, FCM-MRD performed in a multicenter setting is a clinically useful method for MRD-based treatment stratification in BCP-ALL.
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| 16. |
- Ramonet, M., et al.
(författare)
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The fingerprint of the summer 2018 drought in Europe on ground-based atmospheric CO 2 measurements : Atmospheric CO 2 anomaly
- 2020
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Ingår i: Philosophical Transactions of the Royal Society B: Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 375:1810
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Tidskriftsartikel (refereegranskat)abstract
- During the summer of 2018, a widespread drought developed over Northern and Central Europe. The increase in temperature and the reduction of soil moisture have influenced carbon dioxide (CO 2) exchange between the atmosphere and terrestrial ecosystems in various ways, such as a reduction of photosynthesis, changes in ecosystem respiration, or allowing more frequent fires. In this study, we characterize the resulting perturbation of the atmospheric CO 2 seasonal cycles. 2018 has a good coverage of European regions affected by drought, allowing the investigation of how ecosystem flux anomalies impacted spatial CO 2 gradients between stations. This density of stations is unprecedented compared to previous drought events in 2003 and 2015, particularly thanks to the deployment of the Integrated Carbon Observation System (ICOS) network of atmospheric greenhouse gas monitoring stations in recent years. Seasonal CO 2 cycles from 48 European stations were available for 2017 and 2018. Earlier data were retrieved for comparison from international databases or national networks. Here, we show that the usual summer minimum in CO 2 due to the surface carbon uptake was reduced by 1.4 ppm in 2018 for the 10 stations located in the area most affected by the temperature anomaly, mostly in Northern Europe. Notwithstanding, the CO 2 transition phases before and after July were slower in 2018 compared to 2017, suggesting an extension of the growing season, with either continued CO 2 uptake by photosynthesis and/or a reduction in respiration driven by the depletion of substrate for respiration inherited from the previous months due to the drought. For stations with sufficiently long time series, the CO 2 anomaly observed in 2018 was compared to previous European droughts in 2003 and 2015. Considering the areas most affected by the temperature anomalies, we found a higher CO 2 anomaly in 2003 (+3 ppm averaged over 4 sites), and a smaller anomaly in 2015 (+1 ppm averaged over 11 sites) compared to 2018. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'.
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| 17. |
- Serrano, L. M., et al.
(författare)
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The HD 93963 A transiting system: A 1.04d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS
- 2022
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 667
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Tidskriftsartikel (refereegranskat)abstract
- We present the discovery of two small planets transiting HD 93963A (TOI-1797), a GOV star (M-* = 1.109 +/- 0.043M(circle dot), R-* = 1.043 +/- 0.009 R-circle dot) in a visual binary system. We combined TESS and CHEOPS space-borne photometry with MuSCAT 2 ground-based photometry, 'Alopeke and PHARO high-resolution imaging, TRES and FIES reconnaissance spectroscopy, and SOPHIE radial velocity measurements. We validated and spectroscopically confirmed the outer transiting planet HD 93963 A c, a sub-Neptune with an orbital period of P-c approximate to 3.65 d that was reported to be a TESS object of interest (TOI) shortly after the release of Sector 22 data. HD 93963 A c has amass of M-c = 19.2 +/- 4.1 M-circle plus and a radius of R-c = 3.228 +/- 0.059 R-circle plus, implying a mean density of rho(c) = 3.1 +/- 0.7 g cm(-3). The inner object, HD 93963 A b, is a validated 1.04 d ultra-short period (USP) transiting super-Earth that we discovered in the TESS light curve and that was not listed as a TOI, owing to the low significance of its signal (TESS signal-to-noise ratio approximate to 6.7, TESS + CHEOPS combined transit depth D-b = 141.5(-8.3)(+8.5) ppm). We intensively monitored the star with CHEOPS by performing nine transit observations to confirm the presence of the inner planet and validate the system. HD 93963 A b is the first small (R-b = 1.35 +/- 0.042 R-circle plus) USP planet discovered and validated by TESS and CHEOPS. Unlike planet c, HD 93963 Ab is not significantly detected in our radial velocities (M-b = 7.8 +/- 3.2 M-circle plus). The two planets are on either side of the radius valley, implying that they could have undergone completely different evolution processes. We also discovered a linear trend in our Doppler measurements, suggesting the possible presence of a long-period outer planet. With a V-band magnitude of 9.2, HD 93963 A is among the brightest stars known to host a USP planet, making it one of the most favourable targets for precise mass measurement via Doppler spectroscopy and an important laboratory to test formation, evolution, and migration models of planetary systems hosting ultra-short period planets.
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| 18. |
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| 19. |
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| 20. |
- Tulstrup, M., et al.
(författare)
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Effects of germ line DHFR and FPGS variants on methotrexate metabolism and relapse of leukemia
- 2020
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 136:10, s. 1161-1168
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Tidskriftsartikel (refereegranskat)abstract
- Methotrexate (MTX) during maintenance therapy is essential for curing acute lymphoblastic leukemia (ALL), but dosing strategies aiming at adequate treatment intensity are challenged by interindividual differences in drug disposition. To evaluate genetic factors associated with MTX metabolism, we performed a genome-wide association study in 447 ALL cases from the Nordic Society for Pediatric Haematology and Oncology ALL2008 study, validating results in an independent set of 196 patients. The intergenic single-nucleotide polymorphism rs1382539, located in a regulatory element of DHFR, was associated with increased levels of short-chain MTX polyglutamates (P = 1.1 x 10(-8)) related to suppression of enhancer activity, whereas rs35789560 in FPGS (p.R466C, P = 5.6 x 10(-9)) was associated with decreased levels of long-chain MTX polyglutamates through reduced catalytic activity. Furthermore, the FPGS variant was linked with increased relapse risk (P = .044). These findings show a genetic basis for interpatient variability in MTX response and could be used to improve future dosing algorithms.
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| 21. |
- Aad, G., et al.
(författare)
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Anomaly detection search for new resonances decaying into a Higgs boson and a generic new particle X in hadronic final states using √s=13 TeV pp collisions with the ATLAS detector
- 2023
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Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 108:5
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Tidskriftsartikel (refereegranskat)abstract
- A search is presented for a heavy resonance Y decaying into a Standard Model Higgs boson H and a new particle X in a fully hadronic final state. The full Large Hadron Collider run 2 dataset of proton-proton collisions at √s=13 TeV collected by the ATLAS detector from 2015 to 2018 is used and corresponds to an integrated luminosity of 139 fb−1. The search targets the high Y-mass region, where the H and X have a significant Lorentz boost in the laboratory frame. A novel application of anomaly detection is used to define a general signal region, where events are selected solely because of their incompatibility with a learned background-only model. It is constructed using a jet-level tagger for signal-model-independent selection of the boosted X particle, representing the first application of fully unsupervised machine learning to an ATLAS analysis. Two additional signal regions are implemented to target a benchmark X decay into two quarks, covering topologies where the X is reconstructed as either a single large-radius jet or two small-radius jets. The analysis selects Higgs boson decays into , and a dedicated neural-network-based tagger provides sensitivity to the boosted heavy-flavor topology. No significant excess of data over the expected background is observed, and the results are presented as upper limits on the production cross section for signals with mY between 1.5 and 6 TeV and mX between 65 and 3000 GeV.
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| 22. |
- Aad, G., et al.
(författare)
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ATLAS flavour-tagging algorithms for the LHC Run 2 pp collision dataset
- 2023
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Ingår i: European Physical Journal C. - : Institute for Ionics. - 1434-6044 .- 1434-6052. ; 83:7
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Tidskriftsartikel (refereegranskat)abstract
- The flavour-tagging algorithms developed by the ATLAS Collaboration and used to analyse its dataset of √s=13 TeV pp collisions from Run 2 of the Large Hadron Collider are presented. These new tagging algorithms are based on recurrent and deep neural networks, and their performance is evaluated in simulated collision events. These developments yield considerable improvements over previous jet-flavour identification strategies. At the 77% b-jet identification efficiency operating point, light-jet (charm-jet) rejection factors of 170 (5) are achieved in a sample of simulated Standard Model events; similarly, at a c-jet identification efficiency of 30%, a light-jet (b-jet) rejection factor of 70 (9) is obtained.
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| 23. |
- Aad, G., et al.
(författare)
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Calibration of the light-flavour jet mistagging efficiency of the b-tagging algorithms with Z+jets events using 139 fb−1 of ATLAS proton–proton collision data at √s=13 TeV
- 2023
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Ingår i: European Physical Journal C. - : Institute for Ionics. - 1434-6044 .- 1434-6052. ; 83:8
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Tidskriftsartikel (refereegranskat)abstract
- The identification of b-jets, referred to as b-tagging, is an important part of many physics analyses in the ATLAS experiment at the Large Hadron Collider and an accurate calibration of its performance is essential for high-quality physics results. This publication describes the calibration of the light-flavour jet mistagging efficiency in a data sample of proton–proton collision events at √s=13 TeV corresponding to an integrated luminosity of 139 fb−1. The calibration is performed in a sample of Z bosons produced in association with jets. Due to the low mistagging efficiency for light-flavour jets, a method which uses modified versions of the b-tagging algorithms referred to as flip taggers is used in this work. A fit to the jet-flavour-sensitive secondary-vertex mass is performed to extract a scale factor from data, to correct the light-flavour jet mistagging efficiency in Monte Carlo simulations, while simultaneously correcting the b-jet efficiency. With this procedure, uncertainties coming from the modeling of jets from heavy-flavour hadrons are considerably lower than in previous calibrations of the mistagging scale factors, where they were dominant. The scale factors obtained in this calibration are consistent with unity within uncertainties.
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| 24. |
- Aad, G., et al.
(författare)
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Combination of searches for pair-produced leptoquarks at s=13 TeV with the ATLAS detector
- 2024
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 854
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Tidskriftsartikel (refereegranskat)abstract
- A statistical combination of various searches for pair-produced leptoquarks is presented, using the full LHC Run 2 (2015–2018) data set of 139 fb−1 collected with the ATLAS detector from proton–proton collisions at a centre-of-mass energy of s=13 TeV. All possible decays of the leptoquarks into quarks of the third generation and charged or neutral leptons of any generation are investigated. Since no significant deviations from the Standard Model expectation are observed in any of the individual analyses, combined exclusion limits are set on the production cross-sections for scalar and vector leptoquarks. The resulting lower bounds on leptoquark masses exceed those from the individual analyses by up to 100 GeV, depending on the signal hypothesis. © 2024 The Author(s)
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| 25. |
- Aad, G., et al.
(författare)
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Determination of the strong coupling constant from transverse energy-energy correlations in multijet events at √ s=13 TeV with the ATLAS detector
- 2023
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:7
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Tidskriftsartikel (refereegranskat)abstract
- 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.).
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| 26. |
- Aad, G., et al.
(författare)
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Evidence for the Higgs Boson Decay to a Z Boson and a Photon at the LHC
- 2024
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Ingår i: Physical Review Letters. - : American Physical Society (APS). - 0031-9007 .- 1079-7114. ; 132:2
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Tidskriftsartikel (refereegranskat)abstract
- The first evidence for the Higgs boson decay to a Z boson and a photon is presented, with a statistical significance of 3.4 standard deviations. The result is derived from a combined analysis of the searches performed by the ATLAS and CMS Collaborations with proton-proton collision datasets collected at the CERN Large Hadron Collider (LHC) from 2015 to 2018. These correspond to integrated luminosities of around 140 fb−1 for each experiment, at a center-of-mass energy of 13 TeV. The measured signal yield is 2.2±0.7 times the standard model prediction, and agrees with the theoretical expectation within 1.9 standard deviations.
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| 27. |
- Aad, G., et al.
(författare)
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Inclusive and differential cross-sections for dilepton tt¯ production measured in √s=13 TeV pp collisions with the ATLAS detector
- 2023
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- Differential and double-differential distributions of kinematic variables of leptons from decays of top-quark pairs () are measured using the full LHC Run 2 data sample collected with the ATLAS detector. The data were collected at a pp collision energy of √s = 13 TeV and correspond to an integrated luminosity of 140 fb−1. The measurements use events containing an oppositely charged eμ pair and b-tagged jets. The results are compared with predictions from several Monte Carlo generators. While no prediction is found to be consistent with all distributions, a better agreement with measurements of the lepton pT distributions is obtained by reweighting the sample so as to reproduce the top-quark pT distribution from an NNLO calculation. The inclusive top-quark pair production cross-section is measured as well, both in a fiducial region and in the full phase-space. The total inclusive cross-section is found to bewhere the uncertainties are due to statistics, systematic effects, the integrated luminosity and the beam energy. This is in excellent agreement with the theoretical expectation.
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| 28. |
- Aad, G., et al.
(författare)
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Inclusive-photon production and its dependence on photon isolation in pp collisions at √s=13 TeV using 139 fb-1 of ATLAS data
- 2023
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:7
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 29. |
- Aad, G., et al.
(författare)
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Luminosity determination in pp collisions at √s=13 TeV using the ATLAS detector at the LHC
- 2023
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Ingår i: European Physical Journal C. - : Institute for Ionics. - 1434-6044 .- 1434-6052. ; 83:10
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Tidskriftsartikel (refereegranskat)abstract
- The luminosity determination for the ATLAS detector at the LHC during Run 2 is presented, with pp collisions at a centre-of-mass energy s=13 TeV. The absolute luminosity scale is determined using van der Meer beam separation scans during dedicated running periods in each year, and extrapolated to the physics data-taking regime using complementary measurements from several luminosity-sensitive detectors. The total uncertainties in the integrated luminosity for each individual year of data-taking range from 0.9% to 1.1%, and are partially correlated between years. After standard data-quality selections, the full Run 2 pp data sample corresponds to an integrated luminosity of 140.1 ± 1.2 fb - 1 , i.e. an uncertainty of 0.83%. A dedicated sample of low-pileup data recorded in 2017–2018 for precision Standard Model physics measurements is analysed separately, and has an integrated luminosity of 338.1 ± 3.1 pb - 1 . © 2023, The Author(s).
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| 30. |
- Aad, G., et al.
(författare)
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Measurement of the Centrality Dependence of the Dijet Yield in Formula Presented Collisions at Formula Presented with the ATLAS Detector
- 2024
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 132:10
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Tidskriftsartikel (refereegranskat)abstract
- ATLAS measured the centrality dependence of the dijet yield using Formula Presented of Formula Presented data collected at Formula Presented in 2016. The event centrality, which reflects the Formula Presented impact parameter, is characterized by the total transverse energy registered in the Pb-going side of the forward calorimeter. The central-to-peripheral ratio of the scaled dijet yields, Formula Presented, is evaluated, and the results are presented as a function of variables that reflect the kinematics of the initial hard parton scattering process. The Formula Presented shows a scaling with the Bjorken Formula Presented of the parton originating from the proton, Formula Presented, while no such trend is observed as a function of Formula Presented. This analysis provides unique input to understanding the role of small proton spatial configurations in Formula Presented collisions by covering parton momentum fractions from the valence region down to Formula Presented and Formula Presented. © 2024 CERN, for the ATLAS Collaboration.
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| 31. |
- Aad, G., et al.
(författare)
-
Measurement of the H→ γγ and H→ ZZ∗→ 4 ℓ cross-sections in pp collisions at √s=13.6 TeV with the ATLAS detector
- 2024
-
Ingår i: European Physical Journal C. - : Institute for Ionics. - 1434-6044 .- 1434-6052. ; 84:1
-
Tidskriftsartikel (refereegranskat)abstract
- The inclusive Higgs boson production cross-section is measured in the di-photon and the ZZ∗→ 4 ℓ decay channels using 31.4 and 29.0 fb - 1 of pp collision data respectively, collected with the ATLAS detector at a centre-of-mass energy of s=13.6 TeV . To reduce the model dependence, the measurement in each channel is restricted to a particle-level phase space that closely matches the channel’s detector-level kinematic selection, and it is corrected for detector effects. These measured fiducial cross-sections are σfid,γγ= 76-13+14 fb, and σfid,4ℓ= 2.80±0.74 fb, in agreement with the corresponding Standard Model predictions of 67.6 ± 3.7 fb and 3.67 ± 0.19 fb. Assuming Standard Model acceptances and branching fractions for the two channels, the fiducial measurements are extrapolated to the full phase space yielding total cross-sections of σ(pp→H)=67-11+12 pb and 46 ± 12 pb at 13.6 TeV from the di-photon and ZZ∗→ 4 ℓ measurements respectively. The two measurements are combined into a total cross-section measurement of σ(pp→ H) = 58.2 ± 8.7 pb, to be compared with the Standard Model prediction of σ(pp→ H) SM= 59.9 ± 2.6 pb.
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| 32. |
- Aad, G., et al.
(författare)
-
Measurement of the Higgs boson mass with H → γγ decays in 140 fb−1 of s=13 TeV pp collisions with the ATLAS detector
- 2023
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier B.V.. - 0370-2693 .- 1873-2445. ; 847
-
Tidskriftsartikel (refereegranskat)abstract
- The mass of the Higgs boson is measured in the H→γγ decay channel, exploiting the high resolution of the invariant mass of photon pairs reconstructed from the decays of Higgs bosons produced in proton–proton collisions at a centre-of-mass energy s=13 TeV. The dataset was collected between 2015 and 2018 by the ATLAS detector at the Large Hadron Collider, and corresponds to an integrated luminosity of 140 fb−1. The measured value of the Higgs boson mass is 125.17±0.11(stat.)±0.09(syst.) GeV and is based on an improved energy scale calibration for photons, whose impact on the measurement is about four times smaller than in the previous publication. A combination with the corresponding measurement using 7 and 8 TeV pp collision ATLAS data results in a Higgs boson mass measurement of 125.22±0.11(stat.)±0.09(syst.) GeV. With an uncertainty of 1.1 per mille, this is currently the most precise measurement of the mass of the Higgs boson from a single decay channel.
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| 33. |
- Aad, G., et al.
(författare)
-
Measurement of the polarisation of W bosons produced in top-quark decays using dilepton events at √s=13 TeV with the ATLAS experiment
- 2023
-
Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 843
-
Tidskriftsartikel (refereegranskat)abstract
- measurement of the polarisation of W bosons produced in top-quark decays is presented, using proton–proton collision data at a centre-of-mass energy of √s=13 TeV. The data were collected by the ATLAS detector at the Large Hadron Collider and correspond to an integrated luminosity of 139 fb−1. The measurement is performed selecting events decaying into final states with two charged leptons (electrons or muons) and at least two b-tagged jets. The polarisation is extracted from the differential cross-section distribution of the cosθ* variable, where θ* is the angle between the momentum direction of the charged lepton from the W boson decay and the reversed momentum direction of the b-quark from the top-quark decay, both calculated in the W boson rest frame. Parton-level results, corrected for the detector acceptance and resolution, are presented for the cosθ* angle. The measured fractions of longitudinal, left- and right-handed polarisation states are found to be f0=0.684±0.005(stat.)±0.014(syst.), fL=0.318±0.003(stat.)±0.008(syst.) and fR=−0.002±0.002(stat.)±0.014(syst.), in agreement with the Standard Model prediction.
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| 34. |
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| 35. |
- Aad, G., et al.
(författare)
-
Measurement of the production cross-section of J/ψ and ψ(2S) mesons in pp collisions at √s=13 TeV with the ATLAS detector
- 2024
-
Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 84:2
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of the differential production cross-sections of prompt and non-prompt ?/? and ?(2S) mesons with transverse momenta between 8 and 360 GeV and rapidity in the range |?|<2 are reported. Furthermore, measurements of the non-prompt fractions of ?/? and ?(2S), and the prompt and non-prompt ?(2S)-to-?/? production ratios, are presented. The analysis is performed using 140 fb−1 of √?=13 TeV pp collision data recorded by the ATLAS detector at the LHC during the years 2015–2018.
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| 36. |
- Aad, G., et al.
(författare)
-
Measurement of the t¯t¯ cross section and its ratio to the Z production cross section using pp collisions at √s=13.6 TeV with the ATLAS detector
- 2024
-
Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 848
-
Tidskriftsartikel (refereegranskat)abstract
- The inclusive top-quark-pair production cross section ???̄ and its ratio to the ?-boson production cross section have been measured in proton–proton collisions at √? = 13.6 TeV, using 29 fb−1 of data collected in 2022 with the ATLAS experiment at the Large Hadron Collider. Using events with an opposite-charge electron-muon pair and ?-tagged jets, and assuming Standard Model decays, the top-quark-pair production cross section is measured to be ???̄ = 850± 3(stat.) ± 18(syst.) ± 20(lumi.) pb. The ratio of the ??̄ and the ?-boson production cross sections is also measured, where the ?-boson contribution is determined for inclusive ?+?− and ?+?− events in a fiducial phase space. The relative uncertainty on the ratio is reduced compared to the ??̄ cross section, thanks to the cancellation of several systematic uncertainties. The result for the ratio, ???̄∕? = 1.145 ± 0.003(stat.) ± 0.021(syst.)±0.002(lumi.) is consistent with the Standard Model prediction using the PDF4LHC21 PDF set.
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| 37. |
- Aad, G., et al.
(författare)
-
Measurement of the total and differential Higgs boson production cross-sections at √s = 13 TeV with the ATLAS detector by combining the H → ZZ* → 4ℓ and H → γγ decay channels
- 2023
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:5
-
Tidskriftsartikel (refereegranskat)abstract
- The total and differential Higgs boson production cross-sections are measured through a combined statistical analysis of the H → ZZ* → 4ℓ and H → γγ decay channels. The results are based on a dataset of 139 fb−1 of proton–proton collisions at a centre-of-mass energy of 13 TeV, recorded by the ATLAS detector at the Large Hadron Collider. The measured total Higgs boson production cross-section is pb, consistent with the Standard Model prediction of 55.6 ± 2.5 pb. All results from the two decay channels are compatible with each other, and their combination agrees with the Standard Model predictions. A combined statistical interpretation of the measured fiducial cross-sections as a function of the Higgs boson transverse momentum is performed in order to probe the Yukawa couplings to the bottom and charm quarks. A similar interpretation is performed by including also the constraints from the measurements of Higgs boson production in association with a W or Z boson in the and decay channels.
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| 38. |
- Aad, G., et al.
(författare)
-
Measurement of the VH,H → ττ process with the ATLAS detector at 13 TeV
- 2024
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 855
-
Tidskriftsartikel (refereegranskat)abstract
- A measurement of the Standard Model Higgs boson produced in association with a W or Z boson and decaying into a pair of τ-leptons is presented. This search is based on proton-proton collision data collected at s=13 TeV by the ATLAS experiment at the LHC corresponding to an integrated luminosity of 140 fb−1. For the Higgs boson candidate, only final states with at least one τ-lepton decaying hadronically (τ→hadrons+ντ) are considered. For the vector bosons, only leptonic decay channels are considered: Z→ℓℓ and W→ℓνℓ, with ℓ=e,μ. An excess of events over the expected background is found with an observed (expected) significance of 4.2 (3.6) standard deviations, providing evidence of the Higgs boson produced in association with a vector boson and decaying into a pair of τ-leptons. The ratio of the measured cross-section to the Standard Model prediction is μVHττ=1.28−0.29+0.30(stat.)−0.21+0.25(syst.). This result represents the most accurate measurement of the VH(ττ) process achieved to date. © 2024 The Author(s)
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| 39. |
- Aad, G., et al.
(författare)
-
Measurement of ZZ production cross-sections in the four-lepton final state in pp collisions at s=13.6TeV with the ATLAS experiment
- 2024
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier B.V.. - 0370-2693 .- 1873-2445. ; 855
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports cross-section measurements of ZZ production in pp collisions at s=13.6TeV at the Large Hadron Collider. The data were collected by the ATLAS detector in 2022, and correspond to an integrated luminosity of 29 fb−1. Events in the ZZ→4ℓ (ℓ=e, μ) final states are selected and used to measure the inclusive and differential cross-sections in a fiducial region defined close to the analysis selections. The inclusive cross-section is further extrapolated to the total phase space with a requirement of 66
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| 40. |
- Aad, G., et al.
(författare)
-
Measurement of Zγγ production in pp collisions at √s=13 TeV with the ATLAS detector
- 2023
-
Ingår i: European Physical Journal C. - : Institute for Ionics. - 1434-6044 .- 1434-6052. ; 83:6
-
Tidskriftsartikel (refereegranskat)abstract
- Cross-sections for the production of a Z boson in association with two photons are measured in proton–proton collisions at a centre-of-mass energy of 13 TeV. The data used correspond to an integrated luminosity of 139 fb−1 recorded by the ATLAS experiment during Run 2 of the LHC. The measurements use the electron and muon decay channels of the Z boson, and a fiducial phase-space region where the photons are not radiated from the leptons. The integrated Z(→ℓℓ)γγ cross-section is measured with a precision of 12% and differential cross-sections are measured as a function of six kinematic variables of the Zγγ system. The data are compared with predictions from MC event generators which are accurate to up to next-to-leading order in QCD. The cross-section measurements are used to set limits on the coupling strengths of dimension-8 operators in the framework of an effective field theory.
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| 41. |
- Aad, G, et al.
(författare)
-
Measurements of the Higgs boson inclusive and differential fiducial cross sections in the 4 ℓ decay channel at √s = 13 TeV
- 2020
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:10
-
Tidskriftsartikel (refereegranskat)abstract
- Inclusive and differential fiducial cross sections of the Higgs boson are measured in the H→ ZZ∗→ 4 ℓ (ℓ= e, μ) decay channel. The results are based on proton−proton collision data produced at the Large Hadron Collider at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector from 2015 to 2018, equivalent to an integrated luminosity of 139 fb - 1. The inclusive fiducial cross section for the H→ ZZ∗→ 4 ℓ process is measured to be σfid= 3.28 ± 0.32 fb, in agreement with the Standard Model prediction of σfid , SM= 3.41 ± 0.18 fb. Differential fiducial cross sections are measured for a variety of observables which are sensitive to the production and decay of the Higgs boson. All measurements are in agreement with the Standard Model predictions. The results are used to constrain anomalous Higgs boson interactions with Standard Model particles. © 2020, The Author(s).
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| 42. |
- Aad, G., et al.
(författare)
-
Measurements of the suppression and correlations of dijets in Xe+Xe collisions at Formula Presented TeV
- 2023
-
Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 108:2
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of the suppression and correlations of dijets is performed using 3 µ b − 1 of Xe+Xe data at s N N = 5.44 TeV collected with the ATLAS detector at the CERN Large Hadron Collider. Dijets with jets reconstructed using the R = 0.4 anti- k t algorithm are measured differentially in jet p T over the range of 32 to 398 GeV and the centrality of the collisions. Significant dijet momentum imbalance is found in the most central Xe+Xe collisions, which decreases in more peripheral collisions. Results from the measurement of per-pair normalized and absolutely normalized dijet p T balance are compared with previous Pb + Pb measurements at s N N = 5.02 TeV. The differences between the dijet suppression in Xe+Xe and Pb + Pb are further quantified by the ratio of pair nuclear-modification factors. The results are found to be consistent with those measured in Pb + Pb data when compared in classes of the same event activity and when taking into account the difference between the center-of-mass energies of the initial parton scattering process in Xe+Xe and Pb + Pb collisions. These results should provide input for a better understanding of the role of energy density, system size, path length, and fluctuations in the parton energy loss. ©2023 CERN, for the ATLAS Collaboration.
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| 43. |
- Aad, G., et al.
(författare)
-
Measurements of Zγ+jets differential cross sections in pp collisions at √s = 13 TeV with the ATLAS detector
- 2023
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:7
-
Tidskriftsartikel (refereegranskat)abstract
- Differential cross-section measurements of Zγ production in association with hadronic jets are presented, using the full 139 fb−1 dataset of √s = 13 TeV proton–proton collisions collected by the ATLAS detector during Run 2 of the LHC. Distributions are measured using events in which the Z boson decays leptonically and the photon is usually radiated from an initial-state quark. Measurements are made in both one and two observables, including those sensitive to the hard scattering in the event and others which probe additional soft and collinear radiation. Different Standard Model predictions, from both parton-shower Monte Carlo simulation and fixed-order QCD calculations, are compared with the measurements. In general, good agreement is observed between data and predictions from MATRIX and MiNNLOPS, as well as next-to-leading-order predictions from MADGRAPH5_AMC@NLO and SHERPA.
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| 44. |
- Aad, G., et al.
(författare)
-
Observation of an Excess of Dicharmonium Events in the Four-Muon Final State with the ATLAS Detector
- 2023
-
Ingår i: Physical Review Letters. - : APS. - 0031-9007 .- 1079-7114. ; 131:15
-
Tidskriftsartikel (refereegranskat)abstract
- A search is made for potential tetraquarks decaying into a pair of charmonium states in the four muon final state using proton-proton collision data at √s = 13 TeV, corresponding to an integrated luminosity of 140 fb−1 recorded by the ATLAS experiment at LHC. Two decay channels, J/ψ + J/ψ → 4μ and J/ψ + ψ(2S) → 4μ, are studied. Backgrounds are estimated based on a hybrid approach involving Monte Carlo simulations and data-driven methods. Statistically significant excesses with respect to backgrounds dominated by the single parton scattering are seen in the di-J/ψ channel consistent with a narrow resonance at 6.9 GeV and a broader structure at lower mass. A statistically significant excess is also seen in the J/ψ + ψ(2S) channel. The fitted masses and decay widths of the structures are reported.
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| 45. |
- Aad, G., et al.
(författare)
-
Observation of WZγ Production in pp Collisions at √s=13 TeV with the ATLAS Detector
- 2024
-
Ingår i: Physical Review Letters. - : American Physical Society (APS). - 0031-9007 .- 1079-7114. ; 132:2
-
Tidskriftsartikel (refereegranskat)abstract
- This Letter reports the observation of WZγ production and a measurement of its cross section using 140.1±1.2 fb−1 of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The WZγ production cross section, with both the W and Z bosons decaying leptonically, pp→WZγ→ℓ′±νℓ+ℓ−γ (ℓ(′)=e, μ), is measured in a fiducial phase-space region defined such that the leptons and the photon have high transverse momentum and the photon is isolated. The cross section is found to be 2.01±0.30(stat)±0.16(syst) fb. The corresponding standard model predicted cross section calculated at next-to-leading order in perturbative quantum chromodynamics and at leading order in the electroweak coupling constant is 1.50±0.06 fb. The observed significance of the WZγ signal is 6.3σ, compared with an expected significance of 5.0σ.
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| 46. |
- Aad, G., et al.
(författare)
-
Observation of WZγ Production in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector
- 2024
-
Ingår i: Physical Review Letters. - : NA. - 1079-7114 .- 0031-9007. ; 132:2
-
Tidskriftsartikel (refereegranskat)abstract
- This Letter reports the observation of WZγ production and a measurement of its cross section using 140.1±1.2 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The WZγ production cross section, with both the W and Z bosons decaying leptonically, pp→WZγ→ℓ^{'}^{±}νℓ^{+}ℓ^{-}γ (ℓ^{(^{'})}=e, μ), is measured in a fiducial phase-space region defined such that the leptons and the photon have high transverse momentum and the photon is isolated. The cross section is found to be 2.01±0.30(stat)±0.16(syst) fb. The corresponding standard model predicted cross section calculated at next-to-leading order in perturbative quantum chromodynamics and at leading order in the electroweak coupling constant is 1.50±0.06 fb. The observed significance of the WZγ signal is 6.3σ, compared with an expected significance of 5.0σ.
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| 47. |
- Aad, G., et al.
(författare)
-
Observation of Wγγ triboson production in proton-proton collisions at s=13 TeV with the ATLAS detector
- 2024
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier. - 0370-2693 .- 1873-2445. ; 848
-
Tidskriftsartikel (refereegranskat)abstract
- This letter reports the observation of W(ℓν)γγ production in proton-proton collisions. This measurement uses the full Run 2 sample of events recorded at a center-of-mass energy of s=13 TeV by the ATLAS detector at the LHC, corresponding to an integrated luminosity of 140 fb−1. Events with a leptonically-decaying W boson and at least two photons are considered. The background-only hypothesis is rejected with an observed and expected significance of 5.6 standard deviations. The inclusive fiducial production cross section of W(eν)γγ and W(μν)γγ events is measured to be σfid=13.8±1.1(stat)+2.1−2.0(syst)±0.1(lumi) fb, in agreement with the Standard Model prediction.
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| 48. |
- Aad, G., et al.
(författare)
-
Search for an axion-like particle with forward proton scattering in association with photon pairs at ATLAS
- 2023
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:7
-
Tidskriftsartikel (refereegranskat)abstract
- A search for forward proton scattering in association with light-by-light scattering mediated by an axion-like particle is presented, using the ATLAS Forward Proton spectrometer to detect scattered protons and the central ATLAS detector to detect pairs of outgoing photons. Proton-proton collision data recorded in 2017 at a centre-of-mass energy of √s = 13 TeV were analysed, corresponding to an integrated luminosity of 14.6 fb−1. A total of 441 candidate events were selected. A search was made for a narrow resonance in the diphoton mass distribution, corresponding to an axion-like particle (ALP) with mass in the range 150–1600 GeV. No excess is observed above a smooth background. Upper limits on the production cross section of a narrow resonance are set as a function of the mass, and are interpreted as upper limits on the ALP production coupling constant, assuming 100% decay branching ratio into a photon pair. The inferred upper limit on the coupling constant is in the range 0.04–0.09 TeV−1 at 95% confidence level.
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| 49. |
- Aad, G, et al.
(författare)
-
Search for charged-lepton-flavor violating Formula Presented interactions in top-quark production and decay in Formula Presented collisions at Formula Presented with the ATLAS detector at the LHC
- 2024
-
Ingår i: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 110:1
-
Tidskriftsartikel (refereegranskat)abstract
- A search for charged-lepton-flavor violating Formula Presented (Formula Presented, Formula Presented) interactions is presented, considering both top-quark production and decay. The data analyzed correspond to Formula Presented of proton-proton collisions at a center-of-mass energy of Formula Presented recorded with the ATLAS detector at the Large Hadron Collider. The analysis targets events containing two muons with the same electric charge, a hadronically decaying Formula Presented-lepton and at least one jet, with exactly one Formula Presented-tagged jet, produced by a Formula Presented interaction. Agreement with the Standard Model expectation within 1.6 standard deviations is observed, and limits are set at the 95% confidence level (CL) on the charged-lepton-flavor violation branching ratio of Formula Presented. An effective field theory interpretation is performed yielding 95% CL limits on Wilson coefficients, dependent on the flavor of the associated light quark and the Lorentz structure of the coupling. These range from Formula Presented for Formula Presented to Formula Presented for Formula Presented. An additional interpretation is performed for scalar leptoquark production inducing charged-lepton-flavor violation, with fixed intergenerational couplings. Upper limits on leptoquark coupling strengths are set at the 95% CL, ranging from Formula Presented to Formula Presented for leptoquark masses between 0.5 and 2.0 TeV. © 2024 CERN, for the ATLAS Collaboration.
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| 50. |
- Aad, G., et al.
(författare)
-
Search for dark photons from Higgs boson decays via ZH production with a photon plus missing transverse momentum signature from pp collisions at √s=13 TeV with the ATLAS detector
- 2023
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:7
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes a search for dark photons (γd) in proton-proton collisions at √s = 13 TeV at the Large Hadron Collider (LHC). The dark photons are searched for in the decay of Higgs bosons (H → γγd) produced through the ZH production mode. The transverse mass of the system, made of the photon and the missing transverse momentum from the non-interacting γd, presents a distinctive signature as it peaks near the Higgs boson mass. The results presented use the total Run-2 integrated luminosity of 139 fb−1 recorded by the ATLAS detector at the LHC. The dominant reducible background processes are estimated using data-driven techniques. A Boosted Decision Tree technique is adopted to enhance the sensitivity of the search. As no excess is observed with respect to the Standard Model prediction, an observed (expected) upper limit on the branching ratio BR(H → γγd) of 2.28% () is set at 95% CL for massless γd. For massive dark photons up to 40 GeV, the observed (expected) upper limits on BR(H → γγd) at 95% confidence level is found within the [2.19,2.52]% ([2.71,3.11]%) range
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