| 1. |
- Mullier, G.A., et al.
(author)
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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 Formula Presented with the ATLAS experiment
- 2023
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In: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:1
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Journal article (peer-reviewed)abstract
- 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. © 2023 CERN, for the ATLAS Collaboration.
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| 2. |
- Mullier, G.A., et al.
(author)
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Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at √s = 13 TeV with the ATLAS detector
- 2023
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In: Journal of High Energy Physics. - : Springer Science and Business Media Deutschland GmbH. - 1029-8479 .- 1126-6708. ; 2023:6
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Journal article (peer-reviewed)abstract
- 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. [Figure not available: see fulltext.]. © 2023, The Author(s).
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| 3. |
- Mullier, G.A., et al.
(author)
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Measurements of jet observables sensitive to b -quark fragmentation in t t ¯ events at the LHC with the ATLAS detector
- 2022
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In: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 106:3
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Journal article (peer-reviewed)abstract
- 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 tt¯ events, and the associated set of charged-particle tracks is separated into those from the primary pp 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∗. © 2022 CERN.
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| 4. |
- Mullier, G.A., et al.
(author)
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Search for quantum black hole production in lepton + jet final states using proton-proton collisions at vs = 13 TeV with the ATLAS detector
- 2024
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In: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 109:3
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Journal article (peer-reviewed)abstract
- 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. © 2024 CERN, for the ATLAS Collaboration.
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| 5. |
- Mullier, G.A., et al.
(author)
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Measurements of Higgs bosons decaying to bottom quarks from vector boson fusion production with the ATLAS experiment at √s=13TeV
- 2021
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In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 81:6
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Journal article (peer-reviewed)abstract
- The paper presents a measurement of the Standard Model Higgs Boson decaying to b-quark pairs in the vector boson fusion (VBF) production mode. A sample corresponding to 126 fb - 1 of s=13TeV proton–proton collision data, collected with the ATLAS experiment at the Large Hadron Collider, is analyzed utilizing an adversarial neural network for event classification. The signal strength, defined as the ratio of the measured signal yield to that predicted by the Standard Model for VBF Higgs production, is measured to be 0.95-0.36+0.38 , corresponding to an observed (expected) significance of 2.6 (2.8) standard deviations from the background only hypothesis. The results are additionally combined with an analysis of Higgs bosons decaying to b-quarks, produced via VBF in association with a photon. © 2021, CERN for the benefit of the ATLAS collaboration.
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| 6. |
- G., Aad, et al.
(author)
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Measurement of the tt¯ production cross-section and lepton differential distributions in eμ dilepton events from pp collisions at √s=13TeV with the ATLAS detector
- 2020
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In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:6
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Journal article (peer-reviewed)abstract
- The inclusive top quark pair (tt¯) production cross-section σtt¯ has been measured in proton–proton collisions at s=13TeV, using 36.1 fb- 1 of data collected in 2015–2016 by the ATLAS experiment at the LHC. Using events with an opposite-charge eμ pair and b-tagged jets, the cross-section is measured to be: σtt¯=826.4±3.6(stat)±11.5(syst)±15.7(lumi)±1.9(beam)pb,where the uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, the integrated luminosity, and the LHC beam energy, giving a total uncertainty of 2.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. It is used to determine the top quark pole mass via the dependence of the predicted cross-section on mtpole, giving mtpole=173.1-2.1+2.0GeV. It is also combined with measurements at s=7TeV and s=8TeV to derive ratios and double ratios of tt¯ and Z cross-sections at different energies. The same event sample is used to measure absolute and normalised differential cross-sections as functions of single-lepton and dilepton kinematic variables, and the results are compared with predictions from various Monte Carlo event generators. © 2020, CERN for the benefit of the ATLAS collaboration.
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| 7. |
- Milstead, David A., et al.
(author)
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Search for dark matter in events with a hadronically decaying vector boson and missing transverse momentum in pp collisions at √s=13 TeV with the ATLAS detector
- 2018
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In: Journal of High Energy Physics. - : SPRINGER. - 1029-8479 .- 1126-6708. ; 2018:10
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Journal article (peer-reviewed)abstract
- A search for dark matter (DM) particles produced in association with a hadronically decaying vector boson is performed using pp collision data at a centre-of-mass energy of s=13 TeV corresponding to an integrated luminosity of 36.1 fb−1, recorded by the ATLAS detector at the Large Hadron Collider. This analysis improves on previous searches for processes with hadronic decays of W and Z bosons in association with large missing transverse momentum (mono-W/Z searches) due to the larger dataset and further optimization of the event selection and signal region definitions. In addition to the mono-W/Z search, the as yet unexplored hypothesis of a new vector boson Z′ produced in association with dark matter is considered (mono-Z′ search). No significant excess over the Standard Model prediction is observed. The results of the mono-W/Z search are interpreted in terms of limits on invisible Higgs boson decays into dark matter particles, constraints on the parameter space of the simplified vector-mediator model and generic upper limits on the visible cross sections for W/Z+DM production. The results of the mono-Z′ search are shown in the framework of several simplified-model scenarios involving DM production in association with the Z′ boson.[Figure not available: see fulltext.]. © 2018, The Author(s).
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| 8. |
- Mullier, G.A., et al.
(author)
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A search for the dimuon decay of the Standard Model Higgs boson with the ATLAS detector
- 2021
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 812
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Journal article (peer-reviewed)abstract
- A search for the dimuon decay of the Standard Model (SM) Higgs boson is performed using data corresponding to an integrated luminosity of 139 fb−1 collected with the ATLAS detector in Run 2 pp collisions at s=13 TeV at the Large Hadron Collider. The observed (expected) significance over the background-only hypothesis for a Higgs boson with a mass of 125.09 GeV is 2.0σ (1.7σ). The observed upper limit on the cross section times branching ratio for pp→H→μμ is 2.2 times the SM prediction at 95% confidence level, while the expected limit on a H→μμ signal assuming the absence (presence) of a SM signal is 1.1 (2.0). The best-fit value of the signal strength parameter, defined as the ratio of the observed signal yield to the one expected in the SM, is μ=1.2±0.6. © 2020 The Author(s)
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| 9. |
- Mullier, G.A., et al.
(author)
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Constraints on Higgs boson properties using W W∗(→ eνμν) j j production in 36.1 fb−1 of √s = 13 TeV pp collisions with the ATLAS detector
- 2022
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In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 82:7
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Journal article (peer-reviewed)abstract
- This article presents the results of two studies of Higgs boson properties using the W W∗(→ eνμν)j j final state, based on a dataset corresponding to 36.1fb−1of √s = 13 TeV proton–proton collisions recorded by the ATLAS experiment at the Large Hadron Collider. The first study targets Higgs boson production via gluon–gluon fusion and constrains the CP properties of the effective Higgs–gluon interaction. Using angular distributions and the overall rate, a value of tan(α) = 0.0 ± 0.4(stat.) ± 0.3(syst.) is obtained for the tangent of the mixing angle for CP-even and CP-odd contributions. The second study exploits the vector-boson fusion production mechanism to probe the Higgs boson couplings to longitudinally and transversely polarised Wand Z bosons in both the production and the decay of the Higgs boson; these couplings have not been directly constrained previously. The polarisation-dependent coupling strength scale factors are defined as the ratios of the measured polarisation-dependent coupling strengths to those predictedby the Standard Model, and are determined using rate and kinematic information to be aL = 0.91+0.10 −0.18(stat.)+0.09 −0.17(syst.)and aT = 1.2 ± 0.4(stat.)+0.2 −0.3(syst.). These coupling strengths are translated into pseudo-observables, resulting in κV V = 0.91+0.10 −0.18(stat.)+0.09 −0.17(syst.) and ϵV V = 0.13+0.28 −0.20(stat.)+0.08 −0.10(syst.). All results are consistent with the Standard Model predictions.
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| 10. |
- Mullier, G.A., et al.
(author)
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Measurement of the associated production of a Higgs boson decaying into b-quarks with a vector boson at high transverse momentum in pp collisions at s=13 TeV with the ATLAS detector
- 2021
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 816
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Journal article (peer-reviewed)abstract
- The associated production of a Higgs boson with a W or Z boson decaying into leptons and where the Higgs boson decays to a bb¯ pair is measured in the high vector-boson transverse momentum regime, above 250 GeV, with the ATLAS detector. The analysed data, corresponding to an integrated luminosity of 139 fb−1, were collected in proton–proton collisions at the Large Hadron Collider between 2015 and 2018 at a centre-of-mass energy of s=13 TeV. The measured signal strength, defined as the ratio of the measured signal yield to that predicted by the Standard Model, is 0.72−0.36 +0.39 corresponding to an observed (expected) significance of 2.1 (2.7) standard deviations. Cross-sections of associated production of a Higgs boson decaying into b quark pairs with a W or Z gauge boson, decaying into leptons, are measured in two exclusive vector boson transverse momentum regions, 250–400 GeV and above 400 GeV, and interpreted as constraints on anomalous couplings in the framework of a Standard Model effective field theory. © 2021 The Author
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