ORCID Profile
0000-0003-2483-6980
Current Organisation
University of Sussex
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Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2022
Publisher: Springer Science and Business Media LLC
Date: 28-09-2202
Publisher: Springer Science and Business Media LLC
Date: 29-06-2023
Abstract: A search is reported for excited τ -leptons and leptoquarks in events with two hadronically decaying τ -leptons and two or more jets. The search uses proton-proton ( pp ) collision data at $$ \\sqrt{s} $$ s = 13 TeV recorded by the ATLAS experiment during the Run 2 of the Large Hadron Collider in 2015–2018. The total integrated luminosity is 139 fb − 1 . The excited τ -lepton is assumed to be produced and to decay via a four-fermion contact interaction into an ordinary τ -lepton and a quark-antiquark pair. The leptoquarks are assumed to be produced in pairs via the strong interaction, and each leptoquark is assumed to couple to a charm or lighter quark and a τ -lepton. No excess over the background prediction is observed. Excited τ -leptons with masses below 2.8 TeV are excluded at 95% CL in scenarios with the contact interaction scale Λ set to 10 TeV. At the extreme limit of model validity where Λ is set equal to the excited τ -lepton mass, excited τ -leptons with masses below 4.6 TeV are excluded. Leptoquarks with masses below 1.3 TeV are excluded at 95% CL if their branching ratio to a charm quark and a τ -lepton equals 1. The analysis does not exploit flavour-tagging in the signal region.
Publisher: Springer Science and Business Media LLC
Date: 28-07-2021
DOI: 10.1140/EPJC/S10052-023-11837-9
Abstract: A determination of the jet energy scale is presented using proton–proton collision data with a centre-of-mass energy of $$\\sqrt{s}=13$$ s = 13 TeV, corresponding to an integrated luminosity of 140 fb $$^{-1}$$ - 1 collected using the ATLAS detector at the LHC. Jets are reconstructed using the ATLAS particle-flow method that combines charged-particle tracks and topo-clusters formed from energy deposits in the calorimeter cells. The anti- $$k_\\textrm{t}$$ k t jet algorithm with radius parameter $$R=0.4$$ R = 0.4 is used to define the jet. Novel jet energy scale calibration strategies developed for the LHC Run 2 are reported that lay the foundation for the jet calibration in Run 3. Jets are calibrated with a series of simulation-based corrections, including state-of-the-art techniques in jet calibration such as machine learning methods and novel in situ calibrations to achieve better performance than the baseline calibration derived using up to 81 fb $$^{-1}$$ - 1 of Run 2 data. The performance of these new techniques is then examined in the in situ measurements by exploiting the transverse momentum balance between a jet and a reference object. The b -quark jet energy scale using particle flow jets is measured for the first time with around 1% precision using $$\\gamma $$ γ +jet events.
Publisher: Springer Science and Business Media LLC
Date: 03-10-2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-11-2022
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-01-2022
Publisher: Elsevier BV
Date: 10-2020
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2020
Publisher: Springer Science and Business Media LLC
Date: 11-07-2023
Abstract: Measurements of transverse energy-energy correlations and their associated azimuthal asymmetries in multijet events are presented. The analysis is performed using a data s le corresponding to 139 fb − 1 of proton-proton collisions at a centre-of-mass energy of $$ \\sqrt{s} $$ s = 13 TeV, collected with the ATLAS detector at the Large Hadron Collider. The measurements are presented in bins of the scalar sum of the transverse momenta of the two leading jets and unfolded to particle level. They are then compared to next-to-next-to-leading-order perturbative QCD calculations for the first time, which feature a significant reduction in the theoretical uncertainties estimated using variations of the renormalisation and factorisation scales. The agreement between data and theory is good, thus providing a precision test of QCD at large momentum transfers Q . The strong coupling constant α s is extracted as a function of Q , showing a good agreement with the renormalisation group equation and with previous analyses. A simultaneous fit to all transverse energy-energy correlation distributions across different kinematic regions yields a value of $$ {\\alpha}_{\\textrm{s}}\\left({m}_Z\\right)=0.1175\\pm 0.0006{\\left(\\exp .\\right)}_{-0.0017}^{+0.0034}\\left(\\textrm{theo}.\\right) $$ α s m Z = 0.1175 ± 0.0006 exp . − 0.0017 + 0.0034 theo . , while the global fit to the asymmetry distributions yields $$ {\\alpha}_{\\textrm{s}}\\left({m}_Z\\right)=0.1185\\pm 0.0009{\\left(\\exp .\\right)}_{-0.0012}^{+0.0025}\\left(\\textrm{theo}.\\right) $$ α s m Z = 0.1185 ± 0.0009 exp . − 0.0012 + 0.0025 theo . .
Publisher: Springer Science and Business Media LLC
Date: 13-10-2023
Publisher: Elsevier BV
Date: 11-2023
Publisher: Springer Science and Business Media LLC
Date: 23-08-2023
Abstract: This paper describes a search for the single production of an up-type vector-like quark ( T ) decaying as T → Ht or T → Zt . The search utilises a dataset of pp collisions at $$ \\sqrt{s} $$ s = 13 TeV collected with the ATLAS detector during the 2015–2018 data-taking period of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb − 1 . Data are analysed in final states containing a single lepton with multiple jets and b -jets. The presence of boosted heavy resonances in the event is exploited to discriminate the signal from the Standard Model background. No significant excess above the Standard Model expectation is observed, and 95% CL upper limits are set on the production cross section of T quarks in different decay channels. The results are interpreted in several benchmark scenarios to set limits on the mass and universal coupling strength ( κ ) of the vector-like quark. For singlet T quarks, κ values above 0.53 are excluded for all masses below 2.3 TeV. At a mass of 1.6 TeV, κ values as low as 0.35 are excluded. For T quarks in the doublet scenario, where the production cross section is much lower, κ values above 0.72 are excluded for all masses below 1.7 TeV, and this exclusion is extended to κ above 0.55 for low masses around 1.0 TeV.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 03-2023
Publisher: Elsevier BV
Date: 11-2023
Publisher: American Physical Society (APS)
Date: 14-08-2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2023
Publisher: Springer Science and Business Media LLC
Date: 02-10-2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2023
Publisher: American Physical Society (APS)
Date: 16-10-2023
Publisher: Springer Science and Business Media LLC
Date: 26-09-2023
Publisher: Springer Science and Business Media LLC
Date: 08-2023
DOI: 10.1140/EPJC/S10052-023-11584-X
Abstract: This paper presents the muon momentum calibration and performance studies for the ATLAS detector based on the pp collisions data s le produced at $$\\sqrt{s}$$ s = 13 TeV at the LHC during Run 2 and corresponding to an integrated luminosity of 139 $${\\textrm{fb}}^{-1}$$ fb - 1 . An innovative approach is used to correct for potential charge-dependent momentum biases related to the knowledge of the detector geometry, using the $$Z\\rightarrow \\mu ^{+}\\mu ^{-}$$ Z → μ + μ - resonance. The muon momentum scale and resolution are measured using s les of $$J/\\psi \\rightarrow \\mu ^{+}\\mu ^{-}$$ J / ψ → μ + μ - and $$Z\\rightarrow \\mu ^{+}\\mu ^{-}$$ Z → μ + μ - events. A calibration procedure is defined and applied to simulated data to match the performance measured in real data. The calibration is validated using an independent s le of $$\\Upsilon \\rightarrow \\mu ^{+}\\mu ^{-}$$ Υ → μ + μ - events. At the Z $$(J/\\psi )$$ ( J / ψ ) peak, the momentum scale is measured with an uncertainty at the 0.05% (0.1%) level, and the resolution is measured with an uncertainty at the 1.5% (2%) level. The charge-dependent bias is removed with a dedicated in situ correction for momenta up to 450 GeV with a precision better than 0.03 $${\\textrm{TeV}}^{-1}$$ TeV - 1 .
Publisher: American Physical Society (APS)
Date: 09-08-2023
Publisher: Springer Science and Business Media LLC
Date: 23-01-2118
Publisher: Springer Science and Business Media LLC
Date: 12-06-2023
DOI: 10.1140/EPJC/S10052-023-11573-0
Abstract: This paper presents the observation of four-top-quark ( $$t\\bar{t}t\\bar{t}$$ t t ¯ t t ¯ ) production in proton-proton collisions at the LHC. The analysis is performed using an integrated luminosity of 140 $$\\hbox {fb}^{-1}$$ fb - 1 at a centre-of-mass energy of 13 TeV collected using the ATLAS detector. Events containing two leptons with the same electric charge or at least three leptons (electrons or muons) are selected. Event kinematics are used to separate signal from background through a multivariate discriminant, and dedicated control regions are used to constrain the dominant backgrounds. The observed (expected) significance of the measured $$t\\bar{t}t\\bar{t}$$ t t ¯ t t ¯ signal with respect to the standard model (SM) background-only hypothesis is 6.1 (4.3) standard deviations. The $$t\\bar{t}t\\bar{t}$$ t t ¯ t t ¯ production cross section is measured to be $$22.5^{+6.6}_{-5.5}$$ 22 . 5 - 5.5 + 6.6 fb, consistent with the SM prediction of $$12.0 \\pm 2.4$$ 12.0 ± 2.4 fb within 1.8 standard deviations. Data are also used to set limits on the three-top-quark production cross section, being an irreducible background not measured previously, and to constrain the top-Higgs Yukawa coupling and effective field theory operator coefficients that affect $$t\\bar{t}t\\bar{t}$$ t t ¯ t t ¯ production.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-07-2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2023
Publisher: Springer Science and Business Media LLC
Date: 31-07-2023
Abstract: A search for forward proton scattering in association with light-by-light scattering mediated by an axion-like particle is presented, using the ATLAS Forward Proton spectrometer to detect scattered protons and the central ATLAS detector to detect pairs of outgoing photons. Proton-proton collision data recorded in 2017 at a centre-of-mass energy of $$ \\sqrt{s} $$ s = 13 TeV were analysed, corresponding to an integrated luminosity of 14.6 fb − 1 . A total of 441 candidate events were selected. A search was made for a narrow resonance in the diphoton mass distribution, corresponding to an axion-like particle (ALP) with mass in the range 150–1600 GeV. No excess is observed above a smooth background. Upper limits on the production cross section of a narrow resonance are set as a function of the mass, and are interpreted as upper limits on the ALP production coupling constant, assuming 100% decay branching ratio into a photon pair. The inferred upper limit on the coupling constant is in the range 0.04–0.09 TeV − 1 at 95% confidence level.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2018
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2020
Publisher: American Physical Society (APS)
Date: 13-10-2023
Publisher: Elsevier BV
Date: 11-2023
Publisher: Springer Science and Business Media LLC
Date: 13-10-2023
Publisher: American Physical Society (APS)
Date: 11-10-2023
Publisher: Elsevier BV
Date: 11-2023
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jun Wu.