vanjam

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 965 forfattere av denne artikkelen] (2025). Expected tracking performance of the ATLAS Inner Tracker at the High-Luminosity LHC. Journal of Instrumentation (JINST). 20(2). doi: 10.1088/1748-0221/20/02/P02018. Fulltekst i vitenarkiv
• Aad, G.; Aakvaag, Erlend; Abbott, B.; Abbott, D.C.; Abud, Abud Abed & Abeling, K. [Vis alle 2 958 forfattere av denne artikkelen] (2024). Search for pair-produced vectorlike quarks coupling to light quarks in the lepton plus jets final state using 13 TeV pp collisions with the ATLAS detector. Physical Review D. ISSN 2470-0010. 110(5). doi: 10.1103/PhysRevD.110.052009. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 863 forfattere av denne artikkelen] (2024). Probing the CP nature of the top–Higgs Yukawa coupling in tt¯H and tH events with H→bb¯ decays using the ATLAS detector at the LHC. Physics Letters B. ISSN 0370-2693. 849. doi: 10.1016/j.physletb.2024.138469. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 907 forfattere av denne artikkelen] (2024). Search for quantum black hole production in lepton + jet final states using proton-proton collisions at vs = 13 TeV with the ATLAS detector. Physical Review D. ISSN 2470-0010. 109(3). doi: 10.1103/PhysRevD.109.032010. Fulltekst i vitenarkiv Vis sammendrag

  A search for quantum black holes in electron+jet and muon+jet invariant mass spectra is performed with 140  fb−1 of data collected by the ATLAS detector in proton-proton collisions at √𝑠 =13  TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton+jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 908 forfattere av denne artikkelen] (2024). Search for New Phenomena in Two-Body Invariant Mass Distributions Using Unsupervised Machine Learning for Anomaly Detection at √s = 13 TeV with the ATLAS Detector. Physical Review Letters. ISSN 0031-9007. 132(8). doi: 10.1103/PhysRevLett.132.081801. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 907 forfattere av denne artikkelen] (2024). Study of High-Transverse-Momentum Higgs Boson Production in Association with a Vector Boson in the qqbb Final State with the ATLAS Detector. Physical Review Letters. ISSN 0031-9007. 132(13). doi: 10.1103/PhysRevLett.132.131802. Fulltekst i vitenarkiv
• Jackson, P.; Kong, A.X.Y.; Potti, H.; Ruggeri, T.A.; Sharma, A.S. & White, M.J. [Vis alle 2 843 forfattere av denne artikkelen] (2024). Search for high-mass resonances in final states with a τ-lepton and missing transverse momentum with the ATLAS detector. Physical Review D. ISSN 2470-0010. 109(11). doi: 10.1103/PhysRevD.109.112008. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, A. Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 861 forfattere av denne artikkelen] (2024). Deep Generative Models for Fast Photon Shower Simulation in ATLAS. Computing and Software for Big Science. ISSN 2510-2036. 8(1). doi: 10.1007/s41781-023-00106-9. Fulltekst i vitenarkiv
• Aad, G.; Aakvaag, Erlend; Abbott, B.; Abbott, D.C.; Abud, Abud Abed & Abeling, K. [Vis alle 2 958 forfattere av denne artikkelen] (2024). The ATLAS trigger system for LHC Run 3 and trigger performance in 2022. Journal of Instrumentation (JINST). 19(6). doi: 10.1088/1748-0221/19/06/P06029. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S. H. & Aboulhorma, A. [Vis alle 51 forfattere av denne artikkelen] (2023). Measurement of electroweak Z(νν¯)γjj production and limits on anomalous quartic gauge couplings in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. doi: 10.1007/JHEP06(2023)082. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 915 forfattere av denne artikkelen] (2023). Measurement of the CP properties of Higgs boson interactions with τ -leptons with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 83(7). doi: 10.1140/epjc/s10052-023-11583-y. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 910 forfattere av denne artikkelen] (2023). Observation of the γγ→ττ Process in Pb+Pb Collisions and Constraints on the τ-Lepton Anomalous Magnetic Moment with the ATLAS Detector. Physical Review Letters. ISSN 0031-9007. 131(15), s. 151802–151802. doi: 10.1103/PhysRevLett.131.151802. Fulltekst i vitenarkiv
• Jackson, P.; Kong, A.X.Y.; Potti, H.; Ruggeri, T.A.; Sharma, A.S. & Ting, E.X.L. [Vis alle 2 868 forfattere av denne artikkelen] (2023). Search for flavor-changing neutral-current couplings between the top quark and the Z boson with proton-proton collisions at √ s = 13 TeV with the ATLAS detector. Physical Review D. ISSN 2470-0010. 108(3). doi: 10.1103/PhysRevD.108.032019. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 887 forfattere av denne artikkelen] (2023). Measurement of the Higgs boson mass in the H → ZZ^⁎ → 4ℓ decay channel using 139 fb⁻¹ of s=13 TeV pp collisions recorded by the ATLAS detector at the LHC. Physics Letters B. ISSN 0370-2693. 843. doi: 10.1016/j.physletb.2023.137880. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 898 forfattere av denne artikkelen] (2023). Search for resonant WZ production in the fully leptonic final state in proton–proton collisions at √s=13 TeV with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 83(7). doi: 10.1140/epjc/s10052-023-11437-7. Fulltekst i vitenarkiv Vis sammendrag

  A search for a WZ resonance, in the fully leptonic final state (electrons or muons), is performed using 139 fb of data collected at a centre-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The results are interpreted in terms of a singly charged Higgs boson of the Georgi–Machacek model, produced by WZ fusion, and of a Heavy Vector Triplet, with the resonance produced by WZ fusion or the Drell–Yan process. No significant excess over the Standard Model prediction is observed and limits are set on the production cross-section times branching ratio as a function of the resonance mass for these processes.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 955 forfattere av denne artikkelen] (2023). Measurements of the suppression and correlations of dijets in Pb+Pb collisions at^√s<inf>NN</inf> = 5.02 TeV. Physical Review C. ISSN 2469-9985. 107(5). doi: 10.1103/PhysRevC.107.054908. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 913 forfattere av denne artikkelen] (2023). A search for heavy Higgs bosons decaying into vector bosons in same-sign two-lepton final states in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(7). doi: 10.1007/JHEP07(2023)200. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 799 forfattere av denne artikkelen] (2023). Search for dark matter produced in association with a dark Higgs boson decaying into W⁺ W⁻ in the one-lepton final state at √s = 13 TeV using 139 fb⁻¹ of pp collisions recorded with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(7). doi: 10.1007/JHEP07(2023)116. Fulltekst i vitenarkiv Vis sammendrag

  Several extensions of the Standard Model predict the production of dark matter particles at the LHC. A search for dark matter particles produced in association with a dark Higgs boson decaying into W+W− in the ℓ±νqq¯¯′, final states with ℓ = e, μ is presented. This analysis uses 139 fb−1 of pp collisions recorded by the ATLAS detector at a centre-of-mass energy of 13 TeV. The W± → qq′¯¯¯¯ decays are reconstructed from pairs of calorimeter-measured jets or from track-assisted reclustered jets, a technique aimed at resolving the dense topology from a pair of boosted quarks using jets in the calorimeter and tracking information. The observed data are found to agree with Standard Model predictions. Scenarios with dark Higgs boson masses ranging between 140 and 390 GeV are excluded.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 893 forfattere av denne artikkelen] (2023). Observation of Single-Top-Quark Production in Association with a Photon Using the ATLAS Detector. Physical Review Letters. ISSN 0031-9007. 131(18). doi: 10.1103/PhysRevLett.131.181901. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abhayasinghe, D.K. & Abidi, S.H. [Vis alle 2 849 forfattere av denne artikkelen] (2023). Search for pair-production of vector-like quarks in pp collision events at s=13 TeV with at least one leptonically decaying Z boson and a third-generation quark with the ATLAS detector. Physics Letters B. ISSN 0370-2693. 843. doi: 10.1016/j.physletb.2023.138019. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 821 forfattere av denne artikkelen] (2023). Search for a new Z′ gauge boson in 4μ events with the ATLAS experiment. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(7). doi: 10.1007/JHEP07(2023)090. Fulltekst i vitenarkiv Vis sammendrag

  This paper presents a search for a new Z′ vector gauge boson with the ATLAS experiment at the Large Hadron Collider using pp collision data collected at s√ = 13 TeV, corresponding to an integrated luminosity of 139 fb−1. The new gauge boson Z′ is predicted by Lμ − Lτ models to address observed phenomena that can not be explained by the Standard Model. The search examines the four-muon (4μ) final state, using a deep learning neural network classifier to separate the Z′ signal from the Standard Model background events. The di-muon invariant masses in the 4μ events are used to extract the Z′ resonance signature. No significant excess of events is observed over the predicted background. Upper limits at a 95% confidence level on the Z′ production cross-section times the decay branching fraction of pp → Z′μμ → 4μ are set from 0.31 to 4.3 fb for the Z′ mass ranging from 5 to 81 GeV. The corresponding common coupling strengths, gZ′, of the Z′ boson to the second and third generation leptons above 0.003 – 0.2 have been excluded.

• Filmer, E.K.; Jackson, P.; Kong, A.X.Y.; Potti, H.; Ruggeri, T.A. & Ting, E.X.L. [Vis alle 3 206 forfattere av denne artikkelen] (2023). Measurement of substructure-dependent jet suppression in Pb+Pb collisions at 5.02 TeV with the ATLAS detector. Physical Review C. ISSN 2469-9985. 107(5). doi: 10.1103/PhysRevC.107.054909. Fulltekst i vitenarkiv Vis sammendrag

  The ATLAS detector at the Large Hadron Collider has been used to measure jet substructure modification and suppression in Pb+Pb collisions at a nucleon–nucleon center-of-mass energy √sNN=5.02TeV in comparison with proton–proton (pp) collisions at √s=5.02TeV. The Pb+Pb data, collected in 2018, have an integrated luminosity of 1.72nb−1, while the pp data, collected in 2017, have an integrated luminosity of 260pb−1. Jets used in this analysis are clustered using the anti-kt algorithm with a radius parameter R=0.4. The jet constituents, defined by both tracking and calorimeter information, are used to determine the angular scale rg of the first hard splitting inside the jet by reclustering them using the Cambridge–Aachen algorithm and employing the soft-drop grooming technique. The nuclear modification factor, RAA, used to characterize jet suppression in Pb+Pb collisions, is presented differentially in rg, jet transverse momentum, and in intervals of collision centrality. The RAA value is observed to depend significantly on jet rg. Jets produced with the largest measured rg are found to be twice as suppressed as those with the smallest rg in central Pb+Pb collisions. The RAA values do not exhibit a strong variation with jet pT in any of the rg intervals. The rg and pT dependence of jet RAA is qualitatively consistent with a picture of jet quenching arising from coherence and provides the most direct evidence in support of this approach.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, A. Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 857 forfattere av denne artikkelen] (2023). Searches for new phenomena in events with two leptons, jets, and missing transverse momentum in 139 fb ^{- 1} of √s=13 TeV pp collisions with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 83(6). doi: 10.1140/epjc/s10052-023-11434-w. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 788 forfattere av denne artikkelen] (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). ISSN 1126-6708. 2023(7). doi: 10.1007/JHEP07(2023)088. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abidi, S.H. [Vis alle 2 837 forfattere av denne artikkelen] (2023). Search for flavour-changing neutral-current couplings between the top quark and the photon with the ATLAS detector at s=13 TeV. Physics Letters B. ISSN 0370-2693. 842. doi: 10.1016/j.physletb.2022.137379. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 781 forfattere av denne artikkelen] (2023). Search for pair-produced scalar and vector leptoquarks decaying into third-generation quarks and first- or second-generation leptons in pp collisions with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)188. Fulltekst i vitenarkiv Vis sammendrag

  A search for pair-produced scalar and vector leptoquarks decaying into quarks and leptons of different generations is presented. It uses the full LHC Run 2 (2015–2018) data set of 139 fb−1 collected with the ATLAS detector in proton–proton collisions at a centre-of-mass energy of √s = 13 TeV. Scalar leptoquarks with charge −(1/3)e as well as scalar and vector leptoquarks with charge +(2/3)e are considered. All possible decays of the pair-produced leptoquarks into quarks of the third generation (t, b) and charged or neutral leptons of the first or second generation (e, μ, ν) with exactly one electron or muon in the final state are investigated. No significant deviations from the Standard Model expectation are observed. Upper limits on the production cross-section are provided for eight models as a function of the leptoquark mass and the branching ratio of the leptoquark into the charged or neutral lepton. In addition, lower limits on the leptoquark masses are derived for all models across a range of branching ratios. Two of these models have the goal of providing an explanation for the recent B-anomalies. In both models, a vector leptoquark decays into charged and neutral leptons of the second generation with a similar branching fraction. Lower limits of 1980 GeV and 1710 GeV are set on the leptoquark mass for these two models.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 777 forfattere av denne artikkelen] (2023). Cross-section measurements for the production of a Z boson in association with high-transverse-momentum jets in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)080. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 933 forfattere av denne artikkelen] (2023). Search for Higgs boson pair production in association with a vector boson in pp collisions at √s=13TeV with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 83(6). doi: 10.1140/epjc/s10052-023-11559-y. Fulltekst i vitenarkiv Vis sammendrag

  This paper reports a search for Higgs boson pair (hh) production in association with a vector boson (WorZ) using 139 fb−1 of proton–proton collision data at s√=13TeV recorded with the ATLAS detector at the Large Hadron Collider. The search is performed in final states in which the vector boson decays leptonically (W→ℓν,Z→ℓℓ,νν with ℓ=e,μ) and the Higgs bosons each decay into a pair of b-quarks. It targets Vhh signals from both non-resonant hh production, present in the Standard Model (SM), and resonant hh production, as predicted in some SM extensions. A 95% confidence-level upper limit of 183 (87) times the SM cross-section is observed (expected) for non-resonant Vhh production when assuming the kinematics are as expected in the SM. Constraints are also placed on Higgs boson coupling modifiers. For the resonant search, upper limits on the production cross-sections are derived for two specific models: one is the production of a vector boson along with a neutral heavy scalar resonance H, in the mass range 260–1000 GeV, that decays into hh, and the other is the production of a heavier neutral pseudoscalar resonance A that decays into a Z boson and H boson, where the A boson mass is 360–800 GeV and the H boson mass is 260–400 GeV. Constraints are also derived in the parameter space of two-Higgs-doublet models.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 780 forfattere av denne artikkelen] (2023). Search for direct pair production of sleptons and charginos decaying to two leptons and neutralinos with mass splittings near the W-boson mass in √s = 13 TeV pp collisions with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)031. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 782 forfattere av denne artikkelen] (2023). Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)019. Fulltekst i vitenarkiv Vis sammendrag

  A measurement of the top-quark mass (mt) in the tt¯ → 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 mℓμ of the lepton, ℓ (with ℓ = e, μ), from the W-boson decay and the muon, μ, 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 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.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 796 forfattere av denne artikkelen] (2023). Measurement of the tt¯ production cross-section in pp collisions at √s = 5.02 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)138. Fulltekst i vitenarkiv Vis sammendrag

  The inclusive top-quark pair (tt¯) production cross-section σtt¯ is measured in proton–proton collisions at a centre-of-mass energy s√ = 5.02 TeV, using 257 pb−1 of data collected in 2017 by the ATLAS experiment at the LHC. The tt¯ cross-section is measured in both the dilepton and single-lepton final states of the tt¯ system and then combined. The combination of the two measurements yields σtt¯=67.5±0.9(stat.)±2.3(syst.)±1.1(lumi.)±0.2(beam)pb, where the four uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, and imperfect knowledge of both the integrated luminosity and the LHC beam energy, giving a total uncertainty of 3.9%. The result is in agreement with theoretical quantum chromodynamic calculations at next-to-next-to-leading order in the strong coupling constant, including the resummation of next-to-next-to-leading logarithmic soft-gluon terms, and constrains the parton distribution functions of the proton at large Bjorken-x.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abreu, H. & Abulaiti, Y. [Vis alle 2 922 forfattere av denne artikkelen] (2023). Measurement of the total cross section and ρ -parameter from elastic scattering in pp collisions at √s=13 TeV with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 83(5). doi: 10.1140/epjc/s10052-023-11436-8. Fulltekst i vitenarkiv Vis sammendrag

  In a special run of the LHC with β⋆=2.5 km, proton–proton elastic-scattering events were recorded at s√=13 TeV with an integrated luminosity of 340 μb−1 using the ALFA subdetector of ATLAS in 2016. The elastic cross section was measured differentially in the Mandelstam t variable in the range from −t=2.5⋅10−4 GeV2 to −t=0.46 GeV2 using 6.9 million elastic-scattering candidates. This paper presents measurements of the total cross section σtot, parameters of the nuclear slope, and the ρ-parameter defined as the ratio of the real part to the imaginary part of the elastic-scattering amplitude in the limit t→0. These parameters are determined from a fit to the differential elastic cross section using the optical theorem and different parameterizations of the t-dependence. The results for σtot and ρ are σtot(pp→X)=104.7±1.1 mb ,ρ=0.098±0.011. The uncertainty in σtot is dominated by the luminosity measurement, and in ρ by imperfect knowledge of the detector alignment and by modelling of the nuclear amplitude.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 876 forfattere av denne artikkelen] (2023). Measurement of the nuclear modification factor of b-jets in 5.02 TeV Pb+Pb collisions with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 83(5). doi: 10.1140/epjc/s10052-023-11427-9. Fulltekst i vitenarkiv Vis sammendrag

  This paper presents a measurement of b-jet production in Pb+Pb and pp collisions at sNN−−−√=5.02 TeV with the ATLAS detector at the LHC. The measurement uses 260 pb−1 of pp collisions collected in 2017 and 1.4 nb−1 of Pb+Pb collisions collected in 2018. In both collision systems, jets are reconstructed via the anti-kt algorithm. The b-jets are identified from a sample of jets containing muons from the semileptonic decay of b-quarks using template fits of the muon momentum relative to the jet axis. In pp collisions, b-jets are reconstructed for radius parameters R=0.2 and R=0.4, and only R=0.2 jets are used in Pb+Pb collisions. For comparison, inclusive R=0.2 jets are also measured using 1.7 nb−1 of Pb+Pb collisions collected in 2018 and the same pp collision data as the b-jet measurement. The nuclear modification factor, RAA, is calculated for both b-jets and inclusive jets with R=0.2 over the transverse momentum range of 80–290 GeV. The nuclear modification factor for b-jets decreases from peripheral to central collisions. The ratio of the b-jet RAA to inclusive jet RAA is also presented and suggests that the RAA for b-jets is larger than that for inclusive jets in central Pb+Pb collisions. The measurements are compared with theoretical calculations and suggest a role for mass and colour-charge effects in partonic energy loss in heavy-ion collisions.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 792 forfattere av denne artikkelen] (2023). Search for a new scalar resonance in flavour-changing neutral-current top-quark decays t → qX (q = u, c), with X → bb¯ , in proton-proton collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(7). doi: 10.1007/JHEP07(2023)199. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 902 forfattere av denne artikkelen] (2023). Search for doubly charged Higgs boson production in multi-lepton final states using 139 fb ^{- 1} of proton–proton collisions at √s = 13 TeV with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 83(7). doi: 10.1140/epjc/s10052-023-11578-9. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 785 forfattere av denne artikkelen] (2023). Search for resonant and non-resonant Higgs boson pair production in the bb¯ τ⁺τ⁻ decay channel using 13 TeV pp collision data from the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(7). doi: 10.1007/JHEP07(2023)040. Fulltekst i vitenarkiv Vis sammendrag

  A search for Higgs boson pair production in events with two b-jets and two τ-leptons is presented, using a proton–proton collision dataset with an integrated luminosity of 139 fb−1 collected at s√ = 13 TeV by the ATLAS experiment at the LHC. Higgs boson pairs produced non-resonantly or in the decay of a narrow scalar resonance in the mass range from 251 to 1600 GeV are targeted. Events in which at least one τ-lepton decays hadronically are considered, and multivariate discriminants are used to reject the backgrounds. No significant excess of events above the expected background is observed in the non-resonant search. The largest excess in the resonant search is observed at a resonance mass of 1 TeV, with a local (global) significance of 3.1σ (2.0σ). Observed (expected) 95% confidence-level upper limits are set on the non-resonant Higgs boson pair-production cross-section at 4.7 (3.9) times the Standard Model prediction, assuming Standard Model kinematics, and on the resonant Higgs boson pair-production cross-section at between 21 and 900 fb (12 and 840 fb), depending on the mass of the narrow scalar resonance.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 739 forfattere av denne artikkelen] (2023). Search for heavy, long-lived, charged particles with large ionisation energy loss in pp collisions at √s = 13 TeV using the ATLAS experiment and the full Run 2 dataset. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)158. Fulltekst i vitenarkiv Vis sammendrag

  This paper presents a search for hypothetical massive, charged, long-lived particles with the ATLAS detector at the LHC using an integrated luminosity of 139 fb−1 of proton–proton collisions at √s = 13 TeV. These particles are expected to move significantly slower than the speed of light and should be identifiable by their high transverse momenta and anomalously large specific ionisation losses, dE/dx. Trajectories reconstructed solely by the inner tracking system and a dE/dx measurement in the pixel detector layers provide sensitivity to particles with lifetimes down to O (1) ns with a mass, measured using the Bethe–Bloch relation, ranging from 100 GeV to 3 TeV. Interpretations for pair-production of R-hadrons, charginos and staus in scenarios of supersymmetry compatible with these particles being long-lived are presented, with mass limits extending considerably beyond those from previous searches in broad ranges of lifetime.

• Filmer, E.K.; Jackson, P.; Kong, A.X.Y.; Potti, H.; Ruggeri, T.A. & Ting, E.X.L. [Vis alle 2 837 forfattere av denne artikkelen] (2023). Measurements of Higgs boson production by gluon-gluon fusion and vector-boson fusion using H→WW*→eνμν decays in pp collisions at √ s = 13 TeV with the ATLAS detector. Physical Review D. ISSN 2470-0010. 108(3). doi: 10.1103/PhysRevD.108.032005. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 782 forfattere av denne artikkelen] (2023). Search for tt¯ H/ A→ tt¯ tt¯ production in the multilepton final state in proton–proton collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(7). doi: 10.1007/JHEP07(2023)203. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 936 forfattere av denne artikkelen] (2023). Measurements of observables sensitive to colour reconnection in tt¯ events with the ATLAS detector at √s= 13 TeV. European Physical Journal C. ISSN 1434-6044. 83(6). doi: 10.1140/epjc/s10052-023-11479-x. Fulltekst i vitenarkiv Vis sammendrag

  A measurement of observables sensitive to effects of colour reconnection in top-quark pair-production events is presented using 139 of 13 TeV proton–proton collision data collected by the ATLAS detector at the LHC. Events are selected by requiring exactly one isolated electron and one isolated muon with opposite charge and two or three jets, where exactly two jets are required to be b-tagged. For the selected events, measurements are presented for the charged-particle multiplicity, the scalar sum of the transverse momenta of the charged particles, and the same scalar sum in bins of charged-particle multiplicity. These observables are unfolded to the stable-particle level, thereby correcting for migration effects due to finite detector resolution, acceptance and efficiency effects. The particle-level measurements are compared with different colour reconnection models in Monte Carlo generators. These measurements disfavour some of the colour reconnection models and provide inputs to future optimisation of the parameters in Monte Carlo generators.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 898 forfattere av denne artikkelen] (2023). Search for dark matter produced in association with a single top quark and an energetic W boson in √s= 13 TeV pp collisions with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 83(7). doi: 10.1140/epjc/s10052-023-11582-z. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 893 forfattere av denne artikkelen] (2023). Correlations between flow and transverse momentum in Xe + Xe and Pb + Pb collisions at the LHC with the ATLAS detector: A probe of the heavy-ion initial state and nuclear deformation. Physical Review C. ISSN 2469-9985. 107(5). doi: 10.1103/PhysRevC.107.054910. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abdinov, O.; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 922 forfattere av denne artikkelen] (2023). Measurement of muon pairs produced via γγ scattering in nonultraperipheral Pb + Pb collisions at √sNN = 5.02 TeV with the ATLAS detector. Physical Review C. ISSN 2469-9985. 107(5). doi: 10.1103/PhysRevC.107.054907. Fulltekst i vitenarkiv Vis sammendrag

  Results of a measurement of dimuon photoproduction in nonultraperipheral Pb+Pb collisions at √sNN=5.02 TeV are presented. The measurement uses ATLAS data from the 2015 and 2018 Pb+Pb data-taking periods at the LHC with an integrated luminosity of 1.94nb−1. The γγ→μ+μ− pairs are identified via selections on pair momentum asymmetry and acoplanarity. Differential cross sections for dimuon production are measured in different centrality, average muon momentum, and pair rapidity intervals as functions of acoplanarity and k⊥, the transverse momentum kick of one muon relative to the other. Measurements are also made as a function of the rapidity separation of the muons and the angle of the muon pair relative to the second-order event plane to test whether magnetic fields generated in the quark-gluon plasma affect the measured muons. A prior observation of a centrality-dependent broadening of the acoplanarity distribution is confirmed. Furthermore, the improved precision of the measurement reveals a depletion in the number of pairs having small acoplanarity or k⊥ values in more central collisions. The acoplanarity distributions in a given centrality interval are observed to vary with the mean pT of the muons in the pair, but the k⊥ distributions do not. Comparisons with recent theoretical predictions are made. The predicted trends associated with effects of magnetic fields on the dimuons are not observed.

• Filmer, E.K.; Jackson, P.; Kong, A.X.Y.; Potti, H.; Ruggeri, T.A. & Ting, E.X.L. [Vis alle 2 869 forfattere av denne artikkelen] (2023). Strong Constraints on Jet Quenching in Centrality-Dependent p+Pb Collisions at 5.02 TeV from ATLAS. Physical Review Letters. ISSN 0031-9007. 131(7). doi: 10.1103/PhysRevLett.131.072301. Fulltekst i vitenarkiv Vis sammendrag

  Jet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including pp and p+Pb collisions. In contrast, while jet quenching is observed in Pb+Pb collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in 0.36  nb−1 of p+Pb and 3.6  pb−1 of pp collisions at 5.02 TeV. The yields of charged hadrons with pchT>0.5  GeV near and opposite in azimuth to jets with pjetT>30 or 60 GeV, and the ratios of these yields between p+Pb and pp collisions, IpPb, are reported. The collision centrality of p+Pb events is categorized by the energy deposited by forward neutrons from the struck nucleus. The IpPb values are consistent with unity within a few percent for hadrons with pchT>4  GeV at all centralities. These data provide new, strong constraints that preclude almost any parton energy loss in central p+Pb collisions.

• Jackson, P.; Oliver, J.L.; Petridis, A.; Qureshi, A.; Sharma, A.S. & White, M.J. [Vis alle 2 861 forfattere av denne artikkelen] (2023). Measurement of the inclusive tt¯ 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. ISSN 2470-0010. 108(3). doi: 10.1103/PhysRevD.108.032014. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 875 forfattere av denne artikkelen] (2023). Search for heavy long-lived multi-charged particles in the full LHC Run 2 pp collision data at s=13 TeV using the ATLAS detector. Physics Letters B. ISSN 0370-2693. 847. doi: 10.1016/j.physletb.2023.138316. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 788 forfattere av denne artikkelen] (2023). Search for high-mass Wγ and Zγ resonances using hadronic W/Z boson decays from 139 fb⁻¹ of pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(7). doi: 10.1007/JHEP07(2023)125. Fulltekst i vitenarkiv Vis sammendrag

  A search for high-mass charged and neutral bosons decaying to Wγ and Zγ final states is presented in this paper. The analysis uses a data sample of s√ = 13 TeV proton-proton collisions with an integrated luminosity of 139 fb−1 collected by the ATLAS detector during LHC Run 2 operation. The sensitivity of the search is determined using models of the production and decay of spin-1 charged bosons and spin-0/2 neutral bosons. The range of resonance masses explored extends from 1.0 TeV to 6.8 TeV. At these high resonance masses, it is beneficial to target the hadronic decays of the W and Z bosons because of their large branching fractions. The decay products of the high-momentum W/Z bosons are strongly collimated and boosted-boson tagging techniques are employed to improve the sensitivity. No evidence of a signal above the Standard Model backgrounds is observed, and upper limits on the production cross-sections of these bosons times their branching fractions to Wγ and Zγ are derived for various boson production models.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 791 forfattere av denne artikkelen] (2023). Search for boosted diphoton resonances in the 10 to 70 GeV mass range using 138 fb−1 of 13 TeV pp collisions with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(7). doi: 10.1007/JHEP07(2023)155. Fulltekst i vitenarkiv Vis sammendrag

  A search for diphoton resonances in the mass range between 10 and 70 GeV with the ATLAS experiment at the Large Hadron Collider (LHC) is presented. The analysis is based on pp collision data corresponding to an integrated luminosity of 138 fb−1 at a centre-of-mass energy of 13 TeV recorded from 2015 to 2018. Previous searches for diphoton resonances at the LHC have explored masses down to 65 GeV, finding no evidence of new particles. This search exploits the particular kinematics of events with pairs of closely spaced photons reconstructed in the detector, allowing examination of invariant masses down to 10 GeV. The presented strategy covers a region previously unexplored at hadron colliders because of the experimental challenges of recording low-energy photons and estimating the backgrounds. No significant excess is observed and the reported limits provide the strongest bound on promptly decaying axion-like particles coupling to gluons and photons for masses between 10 and 70 GeV.

• Jackson, P.; Kong, A.X.Y.; Oliver, J.L.; Ruggeri, T.A.; Sharma, A.S. & White, M.J. [Vis alle 2 884 forfattere av denne artikkelen] (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 with the ATLAS experiment. Physical Review D. ISSN 2470-0010. 108(1). doi: 10.1103/PhysRevD.108.012022. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 748 forfattere av denne artikkelen] (2023). Search for light long-lived neutral particles that decay to collimated pairs of leptons or light hadrons in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)153. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 916 forfattere av denne artikkelen] (2023). Observation of electroweak production of two jets and a Z-boson pair. Nature Physics. ISSN 1745-2473. 19(2), s. 237–253. doi: 10.1038/s41567-022-01757-y. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 789 forfattere av denne artikkelen] (2023). Differential tt¯ cross-section measurements using boosted top quarks in the all-hadronic final state with 139 fb−1 of ATLAS data. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(4). doi: 10.1007/JHEP04(2023)080. Fulltekst i vitenarkiv Vis sammendrag

  Measurements of single-, double-, and triple-differential cross-sections are presented for boosted top-quark pair-production in 13 TeV proton–proton collisions recorded by the ATLAS detector at the LHC. The top quarks are observed through their hadronic decay and reconstructed as large-radius jets with the leading jet having transverse momentum (pT) greater than 500 GeV. The observed data are unfolded to remove detector effects. The particle-level cross-section, multiplied by the tt¯→WWbb¯¯ branching fraction and measured in a fiducial phase space defined by requiring the leading and second-leading jets to have pT > 500 GeV and pT > 350 GeV, respectively, is 331 ± 3(stat.) ± 39(syst.) fb. This is approximately 20% lower than the prediction of 398+48−49 fb by Powheg+Pythia 8 with next-to-leading-order (NLO) accuracy but consistent within the theoretical uncertainties. Results are also presented at the parton level, where the effects of top-quark decay, parton showering, and hadronization are removed such that they can be compared with fixed-order next-to-next-to-leading-order (NNLO) calculations. The parton-level cross-section, measured in a fiducial phase space similar to that at particle level, is 1.94 ± 0.02(stat.) ± 0.25(syst.) pb. This agrees with the NNLO prediction of 1.96+0.02−0.17 pb. Reasonable agreement with the differential cross-sections is found for most NLO models, while the NNLO calculations are generally in better agreement with the data. The differential cross-sections are interpreted using a Standard Model effective field-theory formalism and limits are set on Wilson coefficients of several four-fermion operators.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 890 forfattere av denne artikkelen] (2023). Constraints on spin-0 dark matter mediators and invisible Higgs decays using ATLAS 13 TeV pp collision data with two top quarks and missing transverse momentum in the final state. European Physical Journal C. ISSN 1434-6044. 83(6). doi: 10.1140/epjc/s10052-023-11477-z. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 806 forfattere av denne artikkelen] (2023). Search for heavy resonances decaying into a Z or W boson and a Higgs boson in final states with leptons and b-jets in 139 fb⁻¹ of pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)016. Fulltekst i vitenarkiv Vis sammendrag

  This article presents a search for new resonances decaying into a Z or W boson and a 125 GeV Higgs boson h, and it targets the νν¯¯¯bb¯¯ , ℓ+ℓ−bb¯¯ , or ℓ±νbb¯¯ final states, where ℓ = e or μ, in proton-proton collisions at s√ = 13 TeV. The data used correspond to a total integrated luminosity of 139 fb−1 collected by the ATLAS detector during Run 2 of the LHC at CERN. The search is conducted by examining the reconstructed invariant or transverse mass distributions of Zh or Wh candidates for evidence of a localised excess in the mass range from 220 GeV to 5 TeV. No significant excess is observed and 95% confidence-level upper limits between 1.3 pb and 0.3 fb are placed on the production cross section times branching fraction of neutral and charged spin-1 resonances and CP-odd scalar bosons. These limits are converted into constraints on the parameter space of the Heavy Vector Triplet model and the two-Higgs-doublet model.

• Filmer, E.K.; Jackson, P.; Kong, A.X.Y.; Potti, H.; Ruggeri, T.A. & Ting, E.X.L. [Vis alle 2 867 forfattere av denne artikkelen] (2023). Search for displaced photons produced in exotic decays of the Higgs boson using 13 TeV pp collisions with the ATLAS detector. Physical Review D. ISSN 2470-0010. 108(3). doi: 10.1103/PhysRevD.108.032016. Fulltekst i vitenarkiv Vis sammendrag

  A search is performed for delayed and nonpointing photons originating from the displaced decay of a neutral long-lived particle (LLP). The analysis uses the full run 2 dataset of proton-proton collisions delivered by the LHC at a center-of-mass energy of √s=13  TeV between 2015 and 2018 and recorded by the ATLAS detector, corresponding to an integrated luminosity of 139  fb−1. The capabilities of the ATLAS electromagnetic calorimeter are exploited to precisely measure the arrival times and trajectories of photons. The results are interpreted in a scenario where the LLPs are pair produced in exotic decays of the 125 GeV Higgs boson, and each LLP subsequently decays into a photon and a particle that escapes direct detection, giving rise to missing transverse momentum. No significant excess is observed above the expectation due to Standard Model background processes. The results are used to set upper limits on the branching ratio of the exotic decay of the Higgs boson. A model-independent limit is also set on the production of photons with large values of displacement and time delay.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 850 forfattere av denne artikkelen] (2023). Production of ϒ(nS) mesons in Pb + Pb and pp collisions at 5.02 TeV. Physical Review C. ISSN 2469-9985. 107(5). doi: 10.1103/PhysRevC.107.054912. Fulltekst i vitenarkiv
• Jackson, P.; Kong, A.X.Y.; Potti, H.; Ruggeri, T.A.; Sharma, A.S. & White, M.J. [Vis alle 2 866 forfattere av denne artikkelen] (2023). Search for the charged-lepton-flavor-violating decay Z→eμ in pp collisions at √ s = 13 TeV with the ATLAS detector. Physical Review D. ISSN 2470-0010. 108(3). doi: 10.1103/PhysRevD.108.032015. Fulltekst i vitenarkiv Vis sammendrag

  A search for the charged-lepton-flavor-violating process Z→eμ is presented, using 139  fb−1 of √s=13  TeV pp collision data collected by the ATLAS experiment at the LHC. An excess in the eμ invariant mass spectrum near the Z boson mass would be a striking signature of new physics. No excess is observed, and an upper limit B(Z→eμ)<2.62×10−7 is placed on the branching fraction at 95% confidence level, which is the most stringent limit to date.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 798 forfattere av denne artikkelen] (2023). Measurement of single top-quark production in the s-channel in proton–proton collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)191. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 928 forfattere av denne artikkelen] (2023). Measurement of exclusive pion pair production in proton–proton collisions at √s=7TeV with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 83(7). doi: 10.1140/epjc/s10052-023-11700-x. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 787 forfattere av denne artikkelen] (2023). Search for flavour-changing neutral current interactions of the top quark and the Higgs boson in events with a pair of τ-leptons in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)155. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 882 forfattere av denne artikkelen] (2023). Measurements of W⁺W^- production in decay topologies inspired by searches for electroweak supersymmetry. European Physical Journal C. ISSN 1434-6044. 83(8). doi: 10.1140/epjc/s10052-023-11508-9. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 848 forfattere av denne artikkelen] (2023). Search for Heavy Neutral Leptons in Decays of W Bosons Using a Dilepton Displaced Vertex in sqrt[s]=13  TeV pp Collisions with the ATLAS Detector. Physical Review Letters. ISSN 0031-9007. 131(6), s. 061803–061803. doi: 10.1103/PhysRevLett.131.061803. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 926 forfattere av denne artikkelen] (2023). Test of CP Invariance in Higgs Boson Vector-Boson-Fusion Production Using the H→γγ Channel with the ATLAS Detector. Physical Review Letters. ISSN 0031-9007. 131(6), s. 061802–061802. doi: 10.1103/PhysRevLett.131.061802. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 917 forfattere av denne artikkelen] (2023). Searches for exclusive Higgs and Z boson decays into a vector quarkonium state and a photon using 139 fb ^{- 1} of ATLAS √s=13 TeV proton–proton collision data. European Physical Journal C. ISSN 1434-6044. 83(9). doi: 10.1140/epjc/s10052-023-11869-1. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 798 forfattere av denne artikkelen] (2023). Exclusive dielectron production in ultraperipheral Pb+Pb collisions at √sNN = 5.02 TeV with ATLAS. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(6). doi: 10.1007/JHEP06(2023)182. Fulltekst i vitenarkiv Vis sammendrag

  Exclusive production of dielectron pairs, γγ → e+e−, is studied using Lint = 1.72 nb−1 of data from ultraperipheral collisions of lead nuclei at √sNN = 5.02 TeV recorded by the ATLAS detector at the LHC. The process of interest proceeds via photon–photon interactions in the strong electromagnetic fields of relativistic lead nuclei. Dielectron production is measured in the fiducial region defined by following requirements: electron transverse momentum peT > 2.5 GeV, absolute electron pseudorapidity |ηe| < 2.5, dielectron invariant mass mee > 5 GeV, and dielectron transverse momentum peeT< 2 GeV. Differential cross-sections are measured as a function of mee, average peT, absolute dielectron rapidity |yee|, and scattering angle in the dielectron rest frame, |cos θ*|, in the inclusive sample, and also with a requirement of no activity in the forward direction. The total integrated fiducial cross-section is measured to be 215±1(stat.)+23−20(syst.)±4(lumi.) μb. Within experimental uncertainties the measured integrated cross-section is in good agreement with the QED predictions from the Monte Carlo programs STARLIGHT and SUPERCHIC, confirming the broad features of the initial photon fluxes. The differential cross-sections show systematic differences from these predictions which are more pronounced at high |yee| and |cos θ*| values.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 781 forfattere av denne artikkelen] (2023). Search for new phenomena in final states with photons, jets and missing transverse momentum in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(7). doi: 10.1007/JHEP07(2023)021. Fulltekst i vitenarkiv Vis sammendrag

  A search for new phenomena has been performed in final states with at least one isolated high-momentum photon, jets and missing transverse momentum in proton–proton collisions at a centre-of-mass energy of s√ = 13 TeV. The data, collected by the ATLAS experiment at the CERN LHC, correspond to an integrated luminosity of 139 fb−1. The experimental results are interpreted in a supersymmetric model in which pair-produced gluinos decay into neutralinos, which in turn decay into a gravitino, at least one photon, and jets. No significant deviations from the predictions of the Standard Model are observed. Upper limits are set on the visible cross section due to physics beyond the Standard Model, and lower limits are set on the masses of the gluinos and neutralinos, all at 95% confidence level. Visible cross sections greater than 0.022 fb are excluded and pair-produced gluinos with masses up to 2200 GeV are excluded for most of the NLSP masses investigated.

• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Study of B+c→J/ψD+s and B+c→J/ψD∗+s decays in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2022(8), s. 1–42. doi: 10.1007/JHEP08(2022)087. Fulltekst i vitenarkiv Vis sammendrag

  A study of B+c→J/ψD+sBc+→J/ψDs+ and B+c→J/ψD∗+sBc+→J/ψDs∗+ decays using 139 fb−1 of integrated luminosity collected with the ATLAS detector from s√s = 13 TeV pp collisions at the LHC is presented. The ratios of the branching fractions of the two decays to the branching fraction of the B+cBc+ → J/ψπ+ decay are measured: B(B+c→J/ψD+s)/B(B+c→J/ψπ+)B(Bc+→J/ψDs+)/B(Bc+→J/ψπ+) = 2.76 ± 0.47 and B(B+c→J/ψD∗+s)/B(B+c→J/ψπ+)B(Bc+→J/ψDs∗+)/B(Bc+→J/ψπ+) = 5.33 ± 0.96. The ratio of the branching fractions of the two decays is found to be B(B+c→J/ψD∗+s)/B(B+c→J/ψD∗+s)B(Bc+→J/ψDs∗+)/B(Bc+→J/ψDs∗+) = 1.93 ± 0.26. For the B+c→J/ψD∗+sBc+→J/ψDs∗+ decay, the transverse polarization fraction, Γ±±/Γ, is measured to be 0.70 ± 0.11. The reported uncertainties include both the statistical and systematic components added in quadrature. The precision of the measurements exceeds that in all previous studies of these decays. These results supersede those obtained in the earlier ATLAS study of the same decays with s√s = 7 and 8 TeV pp collision data. A comparison with available theoretical predictions for the measured quantities is presented.

• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Search for invisible Higgs-boson decays in events with vector-boson fusion signatures using 139 fb−1 of proton-proton data recorded by the ATLAS experiment. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2022:104(8), s. 1–66. doi: 10.1007/JHEP08(2022)104. Fulltekst i vitenarkiv Vis sammendrag

  A direct search for Higgs bosons produced via vector-boson fusion and subsequently decaying into invisible particles is reported. The analysis uses 139 fb−1 of pp collision data at a centre-of-mass energy of s√ = 13 TeV recorded by the ATLAS detector at the LHC. The observed numbers of events are found to be in agreement with the background expectation from Standard Model processes. For a scalar Higgs boson with a mass of 125 GeV and a Standard Model production cross section, an observed upper limit of 0.145 is placed on the branching fraction of its decay into invisible particles at 95% confidence level, with an expected limit of 0.103. These results are interpreted in the context of models where the 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. Invisible decays of additional scalar bosons with masses from 50 GeV to 2 TeV are also studied, and the derived upper limits on the cross section times branching fraction decrease with increasing mass from 1.0 pb for a scalar boson mass of 50 GeV to 0.1 pb at a mass of 2 TeV.

• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Measurements of the Higgs boson inclusive and differential fiducial cross-sections in the diphoton decay channel with pp collisions at √S = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 27(8), s. 1–96. doi: 10.1007/JHEP08(2022)027. Fulltekst i vitenarkiv Vis sammendrag

  A measurement of inclusive and differential fiducial cross-sections for the production of the Higgs boson decaying into two photons is performed using 139 fb−1 of proton-proton collision data recorded at s√ = 13 TeV by the ATLAS experiment at the Large Hadron Collider. The inclusive cross-section times branching ratio, in a fiducial region closely matching the experimental selection, is measured to be 67 ± 6 fb, which is in agreement with the state-of-the-art Standard Model prediction of 64 ± 4 fb. Extrapolating this result to the full phase space and correcting for the branching ratio, the total cross-section for Higgs boson production is estimated to be 58 ± 6 pb. In addition, the cross-sections in four fiducial regions sensitive to various Higgs boson production modes and differential cross-sections as a function of either one or two of several observables are measured. All the measurements are found to be in agreement with the Standard Model predictions. The measured transverse momentum distribution of the Higgs boson is used as an indirect probe of the Yukawa coupling of the Higgs boson to the bottom and charm quarks. In addition, five differential cross-section measurements are used to constrain anomalous Higgs boson couplings to vector bosons in the Standard Model effective field theory framework.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 886 forfattere av denne artikkelen] (2022). Search for heavy particles in the b -tagged dijet mass distribution with additional b -tagged jets in proton-proton collisions at s =13 TeV with the ATLAS experiment. Physical Review D. ISSN 2470-0010. 105(1). doi: 10.1103/PhysRevD.105.012001. Fulltekst i vitenarkiv Vis sammendrag

  A search optimized for new heavy particles decaying to two b-quarks and produced in association with additional b-quarks is reported. The sensitivity is improved by b-tagging at least one lower-pT jet in addition to the two highest-pT jets. The data used in this search correspond to an integrated luminosity of 103  fb−1 collected with a dedicated trijet trigger during the 2017 and 2018 √s=13  TeV proton-proton collision runs with the ATLAS detector at the LHC. The search looks for resonant peaks in the b-tagged dijet invariant mass spectrum over a smoothly falling background. The background is estimated with an innovative data-driven method based on orthonormal functions. The observed b-tagged dijet invariant mass spectrum is compatible with the background-only hypothesis. Upper limits at 95% confidence level on a heavy vector-boson production cross section times branching ratio to a pair of b-quarks are derived.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, A. Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 845 forfattere av denne artikkelen] (2022). The ATLAS inner detector trigger performance in pp collisions at 13 TeV during LHC Run 2. European Physical Journal C. ISSN 1434-6044. 82(3). doi: 10.1140/epjc/s10052-021-09920-0. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 858 forfattere av denne artikkelen] (2022). Measurements of azimuthal anisotropies of jet production in Pb+ Pb collisions at sNN =5.02 TeV with the ATLAS detector. Physical Review C. ISSN 2469-9985. 105(6). doi: 10.1103/PhysRevC.105.064903. Fulltekst i vitenarkiv Vis sammendrag

  The azimuthal variation of jet yields in heavy-ion collisions provides information about the path-length dependence of the energy loss experienced by partons passing through the hot, dense nuclear matter known as the quark–gluon plasma. This paper presents the azimuthal anisotropy coefficients v2, v3, and v4 measured for jets in Pb+Pb collisions at √sNN=5.02 TeV using the ATLAS detector at the LHC. The measurement uses data collected in 2015 and 2018, corresponding to an integrated luminosity of 2.2 nb−1. The vn values are measured as a function of the transverse momentum of the jets between 71 and 398 GeV and the event centrality. A nonzero value of v2 is observed in all but the most central collisions. The value of v2 is largest for jets with lower transverse momentum, with values up to 0.05 in mid-central collisions. A smaller, nonzero value of v3 of approximately 0.01 is measured with no significant dependence on jet pT or centrality, suggesting that fluctuations in the initial state play a small but distinct role in jet energy loss. No significant deviation of v4 from zero is observed in the measured kinematic region.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, A. Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 901 forfattere av denne artikkelen] (2022). Observation of electroweak production of two jets in association with an isolated photon and missing transverse momentum, and search for a Higgs boson decaying into invisible particles at 13 TeV with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 82(2). doi: 10.1140/epjc/s10052-021-09878-z. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 864 forfattere av denne artikkelen] (2022). Search for single production of a vectorlike T quark decaying into a Higgs boson and top quark with fully hadronic final states using the ATLAS detector. Physical Review D. ISSN 2470-0010. 105(9). doi: 10.1103/PhysRevD.105.092012. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 909 forfattere av denne artikkelen] (2022). Search for Higgs bosons decaying into new spin-0 or spin-1 particles in four-lepton final states with the ATLAS detector with 139 fb⁻¹ of pp collision data at √s = 13 TeV. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2022(3). doi: 10.1007/JHEP03(2022)041. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 865 forfattere av denne artikkelen] (2022). Measurement of the nuclear modification factor for muons from charm and bottom hadrons in Pb+Pb collisions at 5.02 TeV with the ATLAS detector. Physics Letters B. ISSN 0370-2693. 829. doi: 10.1016/j.physletb.2022.137077. Fulltekst i vitenarkiv
• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Observation of WWW production in pp collisions at √s=13 TeV with the ATLAS detector. Physical Review Letters. ISSN 0031-9007. 129(6), s. 1–20. doi: 10.1103/PhysRevLett.129.061803. Fulltekst i vitenarkiv Vis sammendrag

  This Letter reports the observation of WWW production and a measurement of its cross section using 139  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. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from WWW production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive WWW production cross section is measured to be 820±100 (stat)±80 (syst)  fb, approximately 2.6 standard deviations from the predicted cross section of 511±18  fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy.

• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Measurement of Higgs boson decay into b-quarks in associated production with a top-quark pair in pp collisions at √S = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2022:97(6), s. 1–63. doi: 10.1007/JHEP06(2022)097. Fulltekst i vitenarkiv Vis sammendrag

  The associated production of a Higgs boson and a top-quark pair is measured in events characterised by the presence of one or two electrons or muons. The Higgs boson decay into a b-quark pair is used. 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 s√s = 13 TeV. The measured signal strength, defined as the ratio of the measured signal yield to that predicted by the Standard Model, is 0.35+0.36−0.340.35−0.34+0.36. This result is compatible with the Standard Model prediction and corresponds to an observed (expected) significance of 1.0 (2.7) standard deviations. The signal strength is also measured differentially in bins of the Higgs boson transverse momentum in the simplified template cross-section framework, including a bin for specially selected boosted Higgs bosons with transverse momentum above 300 GeV.

• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Direct constraint on the Higgs–charm coupling from a search for Higgs boson decays into charm quarks with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 82:717(8), s. 1–42. doi: 10.1140/epjc/s10052-022-10588-3. Fulltekst i vitenarkiv Vis sammendrag

  A search for the Higgs boson decaying into a pair of charm quarks is presented. The analysis uses proton–proton collisions to target the production of a Higgs boson in association with a leptonically decaying W or Z boson. The dataset delivered by the LHC at a centre-of-mass energy of and recorded by the ATLAS detector corresponds to an integrated luminosity of 139 \(\text{ fb}^{-1}\). Flavour-tagging algorithms are used to identify jets originating from the hadronisation of charm quarks. The analysis method is validated with the simultaneous measurement of WW, WZ and ZZ production, with observed (expected) significances of 2.6 (2.2) standard deviations above the background-only prediction for the \((W/Z)Z(\rightarrow c{\bar{c}})\) process and 3.8 (4.6) standard deviations for the \((W/Z)W(\rightarrow cq)\) process. The \((W/Z)H(\rightarrow c {\bar{c}})\) search yields an observed (expected) upper limit of 26 (31) times the predicted Standard Model cross-section times branching fraction for a Higgs boson with a mass of , corresponding to an observed (expected) constraint on the charm Yukawa coupling modifier \(|\kappa _c| < 8.5~(12.4)\), at the 95% confidence level. A combination with the ATLAS \((W/Z)H, H\rightarrow b{\bar{b}}\) analysis is performed, allowing the ratio \(\kappa _c / \kappa _b\) to be constrained to less than 4.5 at the 95% confidence level, smaller than the ratio of the b- and c-quark masses, and therefore determines the Higgs-charm coupling to be weaker than the Higgs-bottom coupling at the 95% confidence level.

• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Search for Higgs boson pair production in the two bottom quarks plus two photons final state in pp collisions at √s=13 TeV with the ATLAS detector. Physical Review D. ISSN 2470-0010. 106:052001(5), s. 1–35. doi: 10.1103/PhysRevD.106.052001. Fulltekst i vitenarkiv Vis sammendrag

  Searches are performed for nonresonant and resonant di-Higgs boson production in the b¯bγγ final state. The dataset used corresponds to an integrated luminosity of 139  fb−1 of proton–proton collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No excess above the expected background is found and upper limits on the di-Higgs boson production cross sections are set. A 95% confidence-level upper limit of 4.2 times the cross section predicted by the Standard Model is set on pp→HH nonresonant production, where the expected limit is 5.7 times the Standard Model predicted value. The expected constraints are obtained for a background hypothesis excluding pp→HH production. The observed (expected) constraints on the Higgs boson trilinear coupling modifier κλ are determined to be [−1.5,6.7] ([−2.4,7.7]) at 95% confidence level, where the expected constraints on κλ are obtained excluding pp→HH production from the background hypothesis. For resonant production of a new hypothetical scalar particle X (X→HH→b¯bγγ), limits on the cross section for pp→X→HH are presented in the narrow-width approximation as a function of mX in the range 251  GeV≤mX≤1000  GeV. The observed (expected) limits on the cross section for pp→X→HH range from 640 fb to 44 fb (391 fb to 46 fb) over the considered mass range.

• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Modelling and computational improvements to the simulation of single vector-boson plus jet processes for the ATLAS experiment. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2022(8), s. 1–61. doi: 10.1007/JHEP08(2022)089. Fulltekst i vitenarkiv Vis sammendrag

  This paper presents updated Monte Carlo configurations used to model the production of single electroweak vector bosons (W, Z/γ∗) in association with jets in proton-proton collisions for the ATLAS experiment at the Large Hadron Collider. Improvements pertaining to the electroweak input scheme, parton-shower splitting kernels and scale-setting scheme are shown for multi-jet merged configurations accurate to next-to-leading order in the strong and electroweak couplings. The computational resources required for these set-ups are assessed, and approximations are introduced resulting in a factor three reduction of the per-event CPU time without affecting the physics modelling performance. Continuous statistical enhancement techniques are introduced by ATLAS in order to populate low cross-section regions of phase space and are shown to match or exceed the generated effective luminosity. This, together with the lower per-event CPU time, results in a 50% reduction in the required computing resources compared to a legacy set-up previously used by the ATLAS collaboration. The set-ups described in this paper will be used for future ATLAS analyses and lay the foundation for the next generation of Monte Carlo predictions for single vector-boson plus jets production.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 893 forfattere av denne artikkelen] (2022). Measurement of the polarisation of single top quarks and antiquarks produced in the t-channel at √s = 13 TeV and bounds on the tWb dipole operator from the ATLAS experiment. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2022(11). doi: 10.1007/JHEP11(2022)040. Fulltekst i vitenarkiv Vis sammendrag

  A simultaneous measurement of the three components of the top-quark and top-antiquark polarisation vectors in t-channel single-top-quark production is presented. This analysis is based on data from proton–proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 139 fb−1, collected with the ATLAS detector at the LHC. Selected events contain exactly one isolated electron or muon, large missing transverse momentum and exactly two jets, one being b-tagged. Stringent selection requirements are applied to discriminate t-channel single-top-quark events from the background contributions. The top-quark and top-antiquark polarisation vectors are measured from the distributions of the direction cosines of the charged-lepton momentum in the top-quark rest frame. The three components of the polarisation vector for the selected top-quark event sample are Px′ = 0.01 ± 0.18, Py′ = −0.029 ± 0.027, Pz′ = 0.91 ± 0.10 and for the top-antiquark event sample they are Px′ = −0.02 ± 0.20, Py′ = −0.007 ± 0.051, Pz′ = 0.79 ± 0.16. Normalised differential cross-sections corrected to a fiducial region at the stable-particle level are presented as a function of the charged-lepton angles for top-quark and top-antiquark events inclusively and separately. These measurements are in agreement with Standard Model predictions. The angular differential cross-sections are used to derive bounds on the complex Wilson coefficient of the dimension-six O tW operator in the framework of an effective field theory. The obtained bounds are CtW ∈ [−0.9, 1.4] and CitW ∈ [−0.8, 0.2], both at 95% confidence level.

• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Measurements of Higgs boson production cross-sections in the H → τ+τ− decay channel in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2022(8), s. 1–81. doi: 10.1007/JHEP08(2022)175. Fulltekst i vitenarkiv Vis sammendrag

  Measurements of the production cross-sections of the Standard Model (SM) Higgs boson (H) decaying into a pair of τ-leptons are presented. The measurements use data collected with the ATLAS detector from pp collisions produced at the Large Hadron Collider at a centre-of-mass energy of s√ = 13 TeV, corresponding to an integrated luminosity of 139 fb−1. Leptonic (τ → ℓνℓντ) and hadronic (τ → hadrons ντ) decays of the τ-lepton are considered. All measurements account for the branching ratio of H → ττ and are performed with a requirement |yH| < 2.5, where yH is the true Higgs boson rapidity. The cross-section of the pp → H → ττ process is measured to be 2.94 ± 0.21(stat)+0.37−0.32(syst) pb, in agreement with the SM prediction of 3.17 ± 0.09 pb. Inclusive cross-sections are determined separately for the four dominant production modes: 2.65 ± 0.41(stat)+0.91−0.67(syst) pb for gluon-gluon fusion, 0.197 ± 0.028(stat)+0.032−0.026(syst) pb for vector-boson fusion, 0.115 ± 0.058(stat)+0.042−0.040(syst) pb for vector-boson associated production, and 0.033 ± 0.031(stat)+0.022−0.017(syst) pb for top-quark pair associated production. Measurements in exclusive regions of the phase space, using the simplified template cross-section framework, are also performed. All results are in agreement with the SM predictions.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 920 forfattere av denne artikkelen] (2022). Constraints on Higgs boson production with large transverse momentum using H →b b ¯ decays in the ATLAS detector. Physical Review D. ISSN 2470-0010. 105(9). doi: 10.1103/PhysRevD.105.092003. Fulltekst i vitenarkiv Vis sammendrag

  This paper reports constraints on Higgs boson production with transverse momentum above 1 TeV. The analyzed data from proton–proton collisions at a center-of-mass energy of 13 TeV were recorded with the ATLAS detector at the Large Hadron Collider from 2015 to 2018 and correspond to an integrated luminosity of 136  fb−1. Higgs bosons decaying into bb¯ are reconstructed as single large-radius jets recoiling against a hadronic system and are identified by the experimental signature of two b-hadron decays. The experimental techniques are validated in the same kinematic regime using the Z→bb¯ process. The 95% confidence-level upper limit on the cross section for Higgs boson production with transverse momentum above 450 GeV is 115 fb, and above 1 TeV it is 9.6 fb. The Standard Model cross section predictions for a Higgs boson with a mass of 125 GeV in the same kinematic regions are 18.4 fb and 0.13 fb, respectively.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, A. Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 864 forfattere av denne artikkelen] (2022). Determination of the parton distribution functions of the proton using diverse ATLAS data from pp collisions at √s=7 , 8 and 13 TeV. European Physical Journal C. ISSN 1434-6044. 82(5). doi: 10.1140/epjc/s10052-022-10217-z. Fulltekst i vitenarkiv Vis sammendrag

  This paper presents an analysis at next-to-next-to-leading order in the theory of quantum chromodynamics for the determination of a new set of proton parton distribution functions using diverse measurements in pp collisions at s√=7, 8 and 13 TeV, performed by the ATLAS experiment at the Large Hadron Collider, together with deep inelastic scattering data from ep collisions at the HERA collider. The ATLAS data sets considered are differential cross-section measurements of inclusive W± and Z/γ∗ boson production, W± and Z boson production in association with jets, tt¯ production, inclusive jet production and direct photon production. In the analysis, particular attention is paid to the correlation of systematic uncertainties within and between the various ATLAS data sets and to the impact of model, theoretical and parameterisation uncertainties. The resulting set of parton distribution functions is called ATLASpdf21.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 877 forfattere av denne artikkelen] (2022). A search for an unexpected asymmetry in the production of e⁺μ⁻ and e⁻μ⁺ pairs in proton–proton collisions recorded by the ATLAS detector at s=13 TeV. Physics Letters B. ISSN 0370-2693. 830. doi: 10.1016/j.physletb.2022.137106. Fulltekst i vitenarkiv
• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 49 forfattere av denne artikkelen] (2022). Measurements of jet observables sensitive to b-quark fragmentation in tt¯ events at the LHC with the ATLAS detector. Physical Review D. ISSN 2470-0010. 106:032008(3), s. 1–33. doi: 10.1103/PhysRevD.106.032008. Fulltekst i vitenarkiv Vis sammendrag

  Several observables sensitive to the fragmentation of b quarks into b hadrons are measured using 36 fb −1 of √s = 13 TeV proton-proton collision data collected with the ATLAS detector at the LHC. Jets containing b hadrons are obtained from a sample of dileptonic t ¯ t events, and the associated set of charged-particle tracks is separated into those from the primary p p interaction vertex and those from the displaced b -decay secondary vertex. This division is used to construct observables that characterize the longitudinal and transverse momentum distributions of the b hadron within the jet. The measurements have been corrected for detector effects and provide a test of heavy-quark-fragmentation modeling at the LHC in a system where the top-quark decay products are color connected to the proton beam remnants. The unfolded distributions are compared with the predictions of several modern Monte Carlo parton-shower generators and generator tunes, and a wide range of agreement with the data is observed, with p values varying from 5 × 10 − 4 to 0.98. These measurements complement similar measurements from e + e − collider experiments in which the b quarks originate from a color singlet Z / γ ∗ .

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, A. Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 842 forfattere av denne artikkelen] (2022). Constraints on Higgs boson properties using WW^∗(→ eνμν) jj production in 36.1^fb-1 of √s=13 TeV pp collisions with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 82(7). doi: 10.1140/epjc/s10052-022-10366-1. Fulltekst i vitenarkiv
• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Search for type-III seesaw heavy leptons in leptonic final states in pp collisions at √s=13 TeV with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 82:998, s. 1–30. doi: 10.1140/epjc/s10052-022-10785-0. Fulltekst i vitenarkiv Vis sammendrag

  A search for the pair production of heavy leptons as predicted by the type-III seesaw mechanism is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13 TeV, corresponding to 139fb−1139fb−1 of integrated luminosity recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. The analysis focuses on final states with three or four electrons or muons from the possible decays of new heavy leptons via intermediate electroweak bosons. No significant deviations above the Standard Model expectation are observed; upper and lower limits on the heavy lepton production cross-section and masses are derived respectively. These results are then combined for the first time with the ones already published by ATLAS using the channel with two leptons in the final state. The observed lower limit on the mass of the type-III seesaw heavy leptons combining two, three and four lepton channels together is 910 GeV at the 95% confidence level.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 893 forfattere av denne artikkelen] (2022). Search for resonant pair production of Higgs bosons in the b b ¯ b b ¯ final state using pp collisions at s =13 TeV with the ATLAS detector. Physical Review D. ISSN 2470-0010. 105(9). doi: 10.1103/PhysRevD.105.092002. Fulltekst i vitenarkiv Vis sammendrag

  A search for resonant Higgs boson pair production in the b¯bb¯b final state is presented. The analysis uses 126  fb−1–139  fb−1 of pp collision data at √s=13  TeV collected with the ATLAS detector at the Large Hadron Collider. The analysis is divided into two channels, targeting Higgs boson decays which are reconstructed as pairs of small-radius jets or as individual large-radius jets. Spin-0 and spin-2 benchmark signal models are considered, both of which correspond to resonant HH production via gluon-gluon fusion. The data are consistent with Standard Model predictions. Upper limits are set on the production cross section times branching ratio to Higgs boson pairs of a new resonance in the mass range from 251  GeV to 5  TeV.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, A. Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 906 forfattere av denne artikkelen] (2022). Measurement of the energy response of the ATLAS calorimeter to charged pions from W±→ τ±(→ π±ντ) ντ events in Run 2 data. European Physical Journal C. ISSN 1434-6044. 82(3). doi: 10.1140/epjc/s10052-022-10117-2. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 865 forfattere av denne artikkelen] (2022). Measurements of differential cross-sections in top-quark pair events with a high transverse momentum top quark and limits on beyond the Standard Model contributions to top-quark pair production with the ATLAS detector at √s = 13 TeV. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2022(6). doi: 10.1007/JHEP06(2022)063. Fulltekst i vitenarkiv Vis sammendrag

  Cross-section measurements of top-quark pair production where the hadronically decaying top quark has transverse momentum greater than 355 GeV and the other top quark decays into ℓνb are presented using 139 fb−1 of data collected by the ATLAS experiment during proton-proton collisions at the LHC. The fiducial cross-section at s√ = 13 TeV is measured to be σ = 1.267 ± 0.005 ± 0.053 pb, where the uncertainties reflect the limited number of data events and the systematic uncertainties, giving a total uncertainty of 4.2%. The cross-section is measured differentially as a function of variables characterising the tt¯ system and additional radiation in the events. The results are compared with various Monte Carlo generators, including comparisons where the generators are reweighted to match a parton-level calculation at next-to-next-to-leading order. The reweighting improves the agreement between data and theory. The measured distribution of the top-quark transverse momentum is used to search for new physics in the context of the effective field theory framework. No significant deviation from the Standard Model is observed and limits are set on the Wilson coefficients of the dimension-six operators OtG and O(8)tq, where the limits on the latter are the most stringent to date.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 866 forfattere av denne artikkelen] (2022). Search for neutral long-lived particles in pp collisions at √s = 13 TeV that decay into displaced hadronic jets in the ATLAS calorimeter. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2022(6). doi: 10.1007/JHEP06(2022)005. Fulltekst i vitenarkiv Vis sammendrag

  A search for decays of pair-produced neutral long-lived particles (LLPs) is presented using 139 fb−1 of proton-proton collision data collected by the ATLAS detector at the LHC in 2015–2018 at a centre-of-mass energy of 13 TeV. Dedicated techniques were developed for the reconstruction of displaced jets produced by LLPs decaying hadronically in the ATLAS hadronic calorimeter. Two search regions are defined for different LLP kinematic regimes. The observed numbers of events are consistent with the expected background, and limits for several benchmark signals are determined. For a SM Higgs boson with a mass of 125 GeV, branching ratios above 10% are excluded at 95% confidence level for values of c times LLP mean proper lifetime in the range between 20 mm and 10 m depending on the model. Upper limits are also set on the cross-section times branching ratio for scalars with a mass of 60 GeV and for masses between 200 GeV and 1 TeV.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, Abud Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 880 forfattere av denne artikkelen] (2022). Search for long-lived charginos based on a disappearing-track signature using 136 fb ^{- 1} of pp collisions at √s = 13 TeV with the ATLAS detector. European Physical Journal C. ISSN 1434-6044. 82(7). doi: 10.1140/epjc/s10052-022-10489-5. Fulltekst i vitenarkiv Vis sammendrag

  A search for long-lived charginos produced either directly or in the cascade decay of heavy prompt gluino states is presented. The search is based on proton–proton collision data collected at a centre-of-mass energy of s√ = 13 TeV between 2015 and 2018 with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 136 fb−1. Long-lived charginos are characterised by a distinct signature of a short and then disappearing track, and are reconstructed using at least four measurements in the ATLAS pixel detector, with no subsequent measurements in the silicon-microstrip tracking volume nor any associated energy deposits in the calorimeter. The final state is complemented by a large missing transverse-momentum requirement for triggering purposes and at least one high-transverse-momentum jet. No excess above the expected backgrounds is observed. Exclusion limits are set at 95% confidence level on the masses of the chargino and gluino for different chargino lifetimes. Chargino masses up to 660 (210) GeV are excluded in scenarios where the chargino is a pure wino (higgsino). For charginos produced during the cascade decay of a heavy gluino, gluinos with masses below 2.1 TeV are excluded for a chargino mass of 300 GeV and a lifetime of 0.2 ns.

• Aad, G.; Abbott, B.; Abbott, D.C.; Abud, A. Abed; Abeling, K. & Abhayasinghe, D.K. [Vis alle 2 923 forfattere av denne artikkelen] (2022). Measurement of the energy asymmetry in tt¯ j production at 13 TeV with the ATLAS experiment and interpretation in the SMEFT framework. European Physical Journal C. ISSN 1434-6044. 82(4). doi: 10.1140/epjc/s10052-022-10101-w. Fulltekst i vitenarkiv Vis sammendrag

  A measurement of the energy asymmetry in jet-associated top-quark pair production is presented using 139fb−1 of data collected by the ATLAS detector at the Large Hadron Collider during pp collisions at s√=13TeV. The observable measures the different probability of top and antitop quarks to have the higher energy as a function of the jet scattering angle with respect to the beam axis. The energy asymmetry is measured in the semileptonic tt¯ decay channel, and the hadronically decaying top quark must have transverse momentum above 350GeV . The results are corrected for detector effects to particle level in three bins of the scattering angle of the associated jet. The measurement agrees with the SM prediction at next-to-leading-order accuracy in quantum chromodynamics in all three bins. In the bin with the largest expected asymmetry, where the jet is emitted perpendicular to the beam, the energy asymmetry is measured to be −0.043±0.020, in agreement with the SM prediction of −0.037±0.003. Interpreting this result in the framework of the Standard Model effective field theory (SMEFT), it is shown that the energy asymmetry is sensitive to the top-quark chirality in four-quark operators and is therefore a valuable new observable in global SMEFT fits.

• Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abud, Adam Abed; Abeling, Kira & Abhayasinghe, Deshan Kavishka [Vis alle 51 forfattere av denne artikkelen] (2022). Two-particle Bose–Einstein correlations in pp collisions at √s=13 TeV measured with the ATLAS detector at the LHC. European Physical Journal C. ISSN 1434-6044. 82(7), s. 1–38. doi: 10.1140/epjc/s10052-022-10472-0. Fulltekst i vitenarkiv Vis sammendrag

  This paper presents studies of Bose–Einstein correlations (BEC) in proton–proton collisions at a centre-of-mass energy of 13 TeV, using data from the ATLAS detector at the CERN Large Hadron Collider. Data were collected in a special low-luminosity configuration with a minimum-bias trigger and a high-multiplicity track trigger, accumulating integrated luminosities of 151 μb−1 and 8.4 nb−1, respectively. The BEC are measured for pairs of like-sign charged particles, each with |η|<2.5, for two kinematic ranges: the first with particle pT>100 MeV and the second with particle pT>500 MeV. The BEC parameters, characterizing the source radius and particle correlation strength, are investigated as functions of charged-particle multiplicity (up to 300) and average transverse momentum of the pair (up to 1.5 GeV). The double-differential dependence on charged-particle multiplicity and average transverse momentum of the pair is also studied. The BEC radius is found to be independent of the charged-particle multiplicity for high charged-particle multiplicity (above 100), confirming a previous observation at lower energy. This saturation occurs independent of the transverse momentum of the pair.

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• Aad, G.; Abbott, B.; Abbott, D. C.; Abeling, K.; Abidi, S. H. & Aboulhorma, A. [Vis alle 2 906 forfattere av denne artikkelen] (2025). Erratum: Search for boosted diphoton resonances in the 10 to 70 GeV mass range using 138 fb−1 of 13 TeV pp collisions with the ATLAS detector. Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2025(12). doi: 10.1007/JHEP12(2025)143. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abbott, D.C.; Abeling, K.; Abidi, S.H. & Aboulhorma, A. [Vis alle 2 902 forfattere av denne artikkelen] (2023). Author Correction: A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery (Nature, (2022), 607, 7917, (52-59), 10.1038/s41586-022-04893-w). Nature. ISSN 0028-0836. 623(7985), s. E5–E5. doi: 10.1038/s41586-023-06248-5. Fulltekst i vitenarkiv
• Aaboud, M.; Aad, G.; Abbott, B.; Abdinov, O.; Abeloos, B. & Abidi, S.H. [Vis alle 2 903 forfattere av denne artikkelen] (2023). Erratum to: Search for exclusive Higgs and Z boson decays to ϕγ and ργ with the ATLAS detector (Journal of High Energy Physics, (2018), 2018, 7, (127), 10.1007/JHEP07(2018)127). Journal of High Energy Physics (JHEP). ISSN 1126-6708. 2023(12). doi: 10.1007/JHEP12(2023)158. Fulltekst i vitenarkiv
• Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R. & Abolins, M. [Vis alle 2 857 forfattere av denne artikkelen] (2022). Erratum to: Search for single top-quark production via flavour-changing neutral currents at 8 TeV with the ATLAS detector (The European Physical Journal C, (2016), 76, 2, (55), 10.1140/epjc/s10052-016-3876-4). European Physical Journal C. ISSN 1434-6044. 82(1). doi: 10.1140/epjc/s10052-021-09929-5. Fulltekst i vitenarkiv

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