0000000000055721

AUTHOR

Philip Patrick Allport

showing 41 related works from this author

Radiation hard monolithic CMOS sensors with small electrodes for High Luminosity LHC

2019

Abstract The upgrade of the tracking detectors for the High Luminosity-LHC (HL-LHC) requires the development of novel radiation hard silicon sensors. The development of Depleted Monolithic Active Pixel Sensors targets the replacement of hybrid pixel detectors with radiation hard monolithic CMOS sensors. We designed, manufactured and tested radiation hard monolithic CMOS sensors in the TowerJazz 180 nm CMOS imaging technology with small electrodes pixel designs. These designs can achieve pixel pitches well below current hybrid pixel sensors (typically 50 ×  50 μ m ) for improved spatial resolution. Monolithic sensors in our design allow to reduce multiple scattering by thinning to a total si…

Nuclear and High Energy PhysicsParticle tracking detectors ; Radiation-hard detectors ; Electronic detector readout concepts ; CMOS sensors ; Monolithic active pixel sensorsPhysics::Instrumentation and DetectorscostsRadiationElectronic detector readout concepts01 natural sciences7. Clean energy030218 nuclear medicine & medical imaging03 medical and health sciences0302 clinical medicinesemiconductor detector: pixelElectronic detector readout conceptCMOS sensorselectrode: designParticle tracking detectors0103 physical sciences[PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det]InstrumentationImage resolutionRadiation hardeningspatial resolutionradiation: damagePhysicsCMOS sensorsemiconductor detector: technologyMonolithic active pixel sensorPixelirradiation010308 nuclear & particles physicsbusiness.industrytracking detector: upgradeDetectorCMOS sensorParticle tracking detectorMonolithic active pixel sensorsUpgradeCERN LHC CollCMOSefficiencyOptoelectronicsbusinessperformanceRadiation-hard detectors
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Search for squarks and gluinos in final states with jets and missing transverse momentum using 36  fb−1 of s=13  TeV pp collision data with the ATLAS…

2018

A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing hadronic jets and missing transverse momentum, but no electrons or muons, is presented ...

PhysicsParticle physicsLarge Hadron ColliderMuon010308 nuclear & particles physicsHigh Energy Physics::LatticeNuclear TheoryHigh Energy Physics::PhenomenologyHadronElementary particleSupersymmetryElectron01 natural sciencesGluon0103 physical sciencesQuark–gluon plasmaHigh Energy Physics::ExperimentNuclear Experiment010306 general physicsPhysical Review D
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Search for top squarks decaying to tau sleptons in pp collisions at s=13  TeV with the ATLAS detector

2018

A search for direct pair production of top squarks in final states with two tau leptons, b-jets, and missing transverse momentum is presented. The analysis is based on proton-proton collision data ...

PhysicsParticle physics010308 nuclear & particles physicsAtlas detectorHigh Energy Physics::PhenomenologySupersymmetryCollision7. Clean energy01 natural sciencesPair production0103 physical sciencesTransverse momentumHigh Energy Physics::ExperimentNuclear Experiment010306 general physicsLeptonPhysical Review D
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Search for New Phenomena in Final States with Two Leptons and One or No b -Tagged Jets at s=13  TeV Using the ATLAS Detector

2021

A search for new phenomena is presented in final states with two leptons and one or no $b$-tagged jets. The event selection requires the two leptons to have opposite charge, the same flavor (electrons or muons), and a large invariant mass. The analysis is based on the full Run-2 proton-proton collision dataset recorded at a center-of-mass energy of $\sqrt{s} = 13$ TeV by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 139 fb$^{-1}$. No significant deviation from the expected background is observed in the data. A four-fermion contact interaction between two quarks ($b,s$) and two leptons ($ee$ or $\mu\mu$), inspired by the $B$-meson decay anomalies, is used as a…

QuarkPhysicsParticle physicsMuonLarge Hadron Collider010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyATLAS experimentGeneral Physics and AstronomyLambdaCoupling (probability)7. Clean energy01 natural sciences0103 physical sciencesHigh Energy Physics::ExperimentInvariant mass010306 general physicsLeptonPhysical Review Letters
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Observation of electroweak W±Z boson pair production in association with two jets in pp collisions at s=13 TeV with the ATLAS detector

2019

An observation of electroweak W±Z production in association with two jets in proton–proton collisions is presented. The data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016 at a centre-of-mass energy of s=13 TeV are used, corresponding to an integrated luminosity of 36.1fb−1 . Events containing three identified leptons, either electrons or muons, and two jets are selected. The electroweak production of W±Z bosons in association with two jets is measured with an observed significance of 5.3 standard deviations. A fiducial cross-section for electroweak production including interference effects and for a single leptonic decay mode is measured to be σWZjj−EW=0.57−0…

PhysicsNuclear and High Energy PhysicsParticle physicsMuonLuminosity (scattering theory)Large Hadron Collider010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyElectroweak interaction7. Clean energy01 natural sciencesPair productionmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesmedicineHigh Energy Physics::Experiment010306 general physicsLeptonBosonPhysics Letters B
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Search for dark matter in association with a Higgs boson decaying to two photons at s=13  TeV with the ATLAS detector

2017

A search for dark matter in association with a Higgs boson decaying to two photons is presented. This study is based on data collected with the ATLAS detector, corresponding to an integrated lumino ...

PhysicsParticle physicsPhotonLarge Hadron ColliderPhysics::Instrumentation and Detectors010308 nuclear & particles physicsAtlas detectorBranching fractionAtlas (topology)Physics beyond the Standard ModelHigh Energy Physics::PhenomenologyDark matter01 natural sciencesNuclear physics0103 physical sciencesHiggs bosonHigh Energy Physics::Experiment010306 general physicsPhysical Review D
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Measurements ofW±Zproduction cross sections inppcollisions ats=8  TeVwith the ATLAS detector and limits on anomalous gauge boson self-couplings

2016

This paper presents measurements of W(+/-)Z production in pp collisions at a center-of-mass energy of 8 TeV. The gauge bosons are reconstructed using their leptonic decay modes into electrons and m ...

PhysicsGauge bosonParticle physics010308 nuclear & particles physicsAtlas detectorHigh Energy Physics::PhenomenologyElectron01 natural sciencesNuclear physicsmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesW′ and Z′ bosonsmedicineHigh Energy Physics::ExperimentProduction (computer science)010306 general physicsPhysical Review D
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Dijet Resonance Search with Weak Supervision Using s=13  TeV pp Collisions in the ATLAS Detector

2020

This Letter describes a search for narrowly resonant new physics using a machine-learning anomaly detection procedure that does not rely on signal simulations for developing the analysis selection. Weakly supervised learning is used to train classifiers directly on data to enhance potential signals. The targeted topology is dijet events and the features used for machine learning are the masses of the two jets. The resulting analysis is essentially a three-dimensional search A→BC, for m_{A}∼O(TeV), m_{B},m_{C}∼O(100  GeV) and B, C are reconstructed as large-radius jets, without paying a penalty associated with a large trials factor in the scan of the masses of the two jets. The full run 2 sq…

PhysicsParticle physicsLarge Hadron ColliderPhysics beyond the Standard ModelHadronGeneral Physics and Astronomy01 natural sciencesStandard Modelmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesmedicineHigh Energy Physics::ExperimentProduction (computer science)Invariant mass010306 general physicsBosonPhysical Review Letters
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Searches for Higgs boson pair production in thehh→bbττ,γγWW*,γγbb,bbbbchannels with the ATLAS detector

2015

Searches for both resonant and nonresonant Higgs boson pair production are performed in the hh -> bb tau tau, gamma gamma WW* final states using 20.3 fb(-1) of pp collision data at a center-of-m ...

PhysicsNuclear and High Energy PhysicsParticle physics010308 nuclear & particles physicsScatteringAtlas detectorHigh Energy Physics::Phenomenology01 natural sciencesGamma gammaNuclear physicsmedicine.anatomical_structurePair productionAtlas (anatomy)0103 physical sciencesmedicineHiggs boson010306 general physicsMinimal Supersymmetric Standard ModelPhysical Review D
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Search for trilepton resonances from chargino and neutralino pair production in s=13  TeV pp collisions with the ATLAS detector

2021

A search is performed for the electroweak pair production of charginos and associated production of a chargino and neutralino, each of which decays through an $R$-parity-violating coupling into a lepton and a $W$, $Z$, or Higgs boson. The trilepton invariant-mass spectrum is constructed from events with three or more leptons, targeting chargino decays that include an electron or muon and a leptonically decaying $Z$ boson. The analyzed dataset corresponds to an integrated luminosity of 139 fb$^{-1}$ of proton-proton collision data produced by the Large Hadron Collider at a center-of-mass energy of $\sqrt{s}$ = 13 TeV and collected by the ATLAS experiment between 2015 and 2018. The data are f…

PhysicsParticle physicsLarge Hadron Collider010308 nuclear & particles physicsPhysics beyond the Standard ModelHigh Energy Physics::PhenomenologySupersymmetry01 natural sciences7. Clean energyChargino0103 physical sciencesNeutralinoHiggs bosonHigh Energy Physics::Experiment010306 general physicsMinimal Supersymmetric Standard ModelLeptonPhysical Review D
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Measurement of the Inelastic Proton-Proton Cross Section at s=13  TeV with the ATLAS Detector at the LHC

2016

This Letter presents a measurement of the inelastic proton-proton cross section using 60  μb^{-1} of pp collisions at a center-of-mass energy sqrt[s] of 13 TeV with the ATLAS detector at the LHC. Inelastic interactions are selected using rings of plastic scintillators in the forward region (2.07 10^{-6}, where M_{X} is the larger invariant mass of the two hadronic systems separated by the largest rapidity gap in the event. In this ξ range the scintillators are highly efficient. For diffractive events this corresponds to cases where at least one proton dissociates to a system with M_{X}>13  GeV. The measured cross section is compared with a range of theoretical predictions. When extrapolated…

PhysicsLarge Hadron ColliderProton010308 nuclear & particles physicsHadronGeneral Physics and Astronomy01 natural sciencesNuclear physicsCross section (physics)medicine.anatomical_structureAtlas (anatomy)0103 physical sciencesmedicineHigh Energy Physics::ExperimentInvariant massRapidity010306 general physicsEnergy (signal processing)Physical Review Letters
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Search for the Production of a Long-Lived Neutral Particle Decaying within the ATLAS Hadronic Calorimeter in Association with a Z Boson from pp Colli…

2019

This Letter presents a search for the production of a long-lived neutral particle (Zd) decaying within the ATLAS hadronic calorimeter, in association with a standard model (SM) Z boson produced via an intermediate scalar boson, where Z→+ (=e, μ). The data used were collected by the ATLAS detector during 2015 and 2016 pp collisions with a center-of-mass energy of s=13 TeV at the Large Hadron Collider and correspond to an integrated luminosity of 36.1±0.8 fb-1. No significant excess of events is observed above the expected background. Limits on the production cross section of the scalar boson times its decay branching fraction into the long-lived neutral particle are derived as a function of …

PhysicsParticle physicsLarge Hadron ColliderBranching fractionHadronGeneral Physics and AstronomyScalar boson01 natural sciences0103 physical sciencesHiggs bosonHigh Energy Physics::ExperimentNeutron010306 general physicsNeutral particleBosonPhysical Review Letters
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Search for resonances in the mass distribution of jet pairs with one or two jets identified as b-jets in proton–proton collisions at s=13 TeV with th…

2016

Searches for high-mass resonances in the dijet invariant mass spectrum with one or two jets identified as $b$-jets are performed using an integrated luminosity of $3.2$ fb$^{-1}$ of proton--proton collisions with a centre-of-mass energy of $\sqrt{s}=13$ TeV recorded by the ATLAS detector at the Large Hadron Collider. No evidence of anomalous phenomena is observed in the data, which are used to exclude, at 95% credibility level, excited $b^{*}$ quarks with masses from 1.1 TeV to 2.1 TeV and leptophobic $Z'$ bosons with masses from 1.1 TeV to 1.5 TeV. Contributions of a Gaussian signal shape with effective cross sections ranging from approximately 0.4 to 0.001 pb are also excluded in the mass…

QuarkPhysicsNuclear and High Energy PhysicsParticle physicsLarge Hadron ColliderProtonMass distribution010308 nuclear & particles physicsAstrophysics::High Energy Astrophysical PhenomenaHigh Energy Physics::Phenomenology01 natural sciencesLuminosityNuclear physicsmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesmedicinePhysics::Accelerator PhysicsHigh Energy Physics::ExperimentInvariant mass010306 general physicsBosonPhysics Letters B
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Search for heavy resonances decaying to a photon and a hadronically decaying Z/W/H boson in pp collisions at s=13  TeV with the ATLAS detector

2018

This Letter presents a search for the production of new heavy resonances decaying into a Higgs boson and a photon using proton-proton collision data at √ s = 13     TeV collected by the ATLAS detector at the LHC. The data correspond to an integrated luminosity of 139     fb − 1 . The analysis is performed by reconstructing hadronically decaying Higgs boson ( H → b ¯ b ) candidates as single large-radius jets. A novel algorithm using information about the jet constituents in the center-of-mass frame of the jet is implemented to identify the two b quarks in the single jet. No significant excess of events is observed above the expected background. Upper limits are set on the production cross-s…

PhysicsQuarkParticle physicsTop quarkPhotonLarge Hadron Collider010308 nuclear & particles physicsBranching fractionHigh Energy Physics::PhenomenologyParton01 natural sciences0103 physical sciencesHiggs bosonHigh Energy Physics::Experiment010306 general physicsBosonPhysical Review D
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Search for new phenomena in dijet events using 37  fb−1 of pp collision data collected at s=13  TeV with the ATLAS detector

2017

Dijet events are studied in the proton-proton collision dataset recorded at root s = 13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to integrated lumino ...

PhysicsParticle physicsLarge Hadron ColliderPhysics::Instrumentation and Detectors010308 nuclear & particles physicsAtlas detectorHigh Energy Physics::PhenomenologyCollision01 natural sciencesNuclear physicsAngular distributionmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesmedicinePhysics::Accelerator PhysicsHigh Energy Physics::ExperimentNuclear Experiment010306 general physicsPhysical Review D
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Measurement of the suppression and azimuthal anisotropy of muons from heavy-flavor decays in Pb+Pb collisions at sNN=2.76 TeV with the ATLAS detector

2018

ATLAS measurements of the production of muons from heavy-flavor decays in root s(NN) = 2.76 TeV Pb+Pb collisions and root s = 2.76 TeV pp collisions at the LHC are presented. Integrated luminositie ...

PhysicsLarge Hadron ColliderMuonPhysics::Instrumentation and Detectors010308 nuclear & particles physicsAtlas detectorHigh Energy Physics::PhenomenologyHadron01 natural sciencesAzimuthNuclear physicsmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesmedicinePhysics::Accelerator PhysicsHigh Energy Physics::ExperimentAngular dependenceNuclear Experiment010306 general physicsAnisotropyPhysical Review C
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Measurements of spin correlation in top-antitop quark events from proton-proton collisions ats=7  TeVusing the ATLAS detector

2014

Measurements of spin correlation in top quark pair production are presented using data collected with the ATLAS detector at the LHC with proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 4.6 fb(-1). Events are selected in final states with two charged leptons and at least two jets and in final states with one charged lepton and at least four jets. Four different observables sensitive to different properties of the top quark pair production mechanism are used to extract the correlation between the top and antitop quark spins. Some of these observables are measured for the first time. The measurements are in good agreement with the Stan…

QuarkPhysicsNuclear and High Energy PhysicsParticle physicsTop quarkLarge Hadron Collider010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyTevatron01 natural sciences7. Clean energyBottom quarkNuclear physicsPair production0103 physical sciencesHigh Energy Physics::Experiment010306 general physicsLeptonBosonPhysical Review D
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Search for direct stau production in events with two hadronic τ -leptons in s=13  TeV pp collisions with the ATLAS detector

2020

A search for the direct production of the supersymmetric partners of τ -leptons (staus) in final states with two hadronically decaying τ -leptons is presented. The analysis uses a dataset of p p collisions corresponding to an integrated luminosity of 139     fb − 1 , recorded with the ATLAS detector at the Large Hadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected Standard Model background is observed. Limits are derived in scenarios of direct production of stau pairs with each stau decaying into the stable lightest neutralino and one τ -lepton in simplified models where the two stau mass eigenstates are degenerate. Stau masses from 120 GeV to 390…

PhysicsParticle physicsLarge Hadron Collider010308 nuclear & particles physicsHigh Energy Physics::PhenomenologySupersymmetry7. Clean energy01 natural sciencesStandard ModelMassless particlePair productionmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesNeutralinomedicineHigh Energy Physics::Experiment010306 general physicsLeptonPhysical Review D
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Search for Higgs andZBoson Decays toϕγwith the ATLAS Detector

2016

A search for the decays of the Higgs and Z bosons to a ϕ meson and a photon is performed with a pp collision data sample corresponding to an integrated luminosity of 2.7  fb^{-1} collected at sqrt[s]=13  TeV with the ATLAS detector at the LHC. No significant excess of events is observed above the background, and 95% confidence level upper limits on the branching fractions of the Higgs and Z boson decays to ϕγ of 1.4×10^{-3} and 8.3×10^{-6}, respectively, are obtained.

PhysicsParticle physicsLarge Hadron ColliderLuminosity (scattering theory)Meson010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyElectroweak interactionGeneral Physics and AstronomyPhi meson01 natural sciencesNuclear physicsmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesmedicineHiggs bosonHigh Energy Physics::Experiment010306 general physicsBosonPhysical Review Letters
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Measurement of the correlation between the polar angles of leptons from top quark decays in the helicity basis ats=7  TeVusing the ATLAS detector

2016

A measurement of the correlations between the polar angles of leptons from the decay of pair-produced t and (t) over bar quarks in the helicity basis is reported, using proton-proton collision data collected by the ATLAS detector at the LHC. The dataset corresponds to an integrated luminosity of 4.6 fb(-1) at a center-of-mass energy of root s = 7 TeV collected during 2011. Candidate events are selected in the dilepton topology with large missing transverse momentum and at least two jets. The angles theta(1) and theta(2) between the charged leptons and the direction of motion of the parent quarks in the t (t) over bar rest frame are sensitive to the spin information, and the distribution of …

PhysicsQuarkTop quarkParticle physics010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyPartonRest frame7. Clean energy01 natural sciencesHelicityNuclear physicsPair production0103 physical sciencesHigh Energy Physics::ExperimentHelicity basis010306 general physicsLeptonPhysical Review D
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Longitudinal Flow Decorrelations in Xe+Xe Collisions at sNN=5.44  TeV with the ATLAS Detector

2021

The first measurement of longitudinal decorrelations of harmonic flow amplitudes v_{n} for n=2-4 in Xe+Xe collisions at sqrt[s_{NN}]=5.44  TeV is obtained using 3  μb^{-1} of data with the ATLAS detector at the LHC. The decorrelation signal for v_{3} and v_{4} is found to be nearly independent of collision centrality and transverse momentum (p_{T}) requirements on final-state particles, but for v_{2} a strong centrality and p_{T} dependence is seen. When compared with the results from Pb+Pb collisions at sqrt[s_{NN}]=5.02  TeV, the longitudinal decorrelation signal in midcentral Xe+Xe collisions is found to be larger for v_{2}, but smaller for v_{3}. Current hydrodynamic models reproduce th…

PhysicsLarge Hadron ColliderAtlas detectorGeneral Physics and Astronomy01 natural sciencesNuclear physicsAmplitudemedicine.anatomical_structureFlow (mathematics)Atlas (anatomy)0103 physical sciencesTransverse momentumQuark–gluon plasmamedicine010306 general physicsPhysical Review Letters
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Search for supersymmetry in events with four or more leptons in s=13  TeV pp collisions with ATLAS

2018

Results from a search for supersymmetry in events with four or more charged leptons (electrons, muons and taus) are presented. The analysis uses a data sample corresponding to 36.1 fb-1 of proton-proton collisions delivered by the Large Hadron Collider at s=13 TeV and recorded by the ATLAS detector. Four-lepton signal regions with up to two hadronically decaying taus are designed to target a range of supersymmetric scenarios that can be either enriched in or depleted of events involving the production and decay of a Z boson. Data yields are consistent with Standard Model expectations and results are used to set upper limits on the event yields from processes beyond the Standard Model. Exclu…

PhysicsGluinoParticle physicsLarge Hadron Collider010308 nuclear & particles physicsPhysics beyond the Standard ModelHigh Energy Physics::PhenomenologySupersymmetry01 natural sciencesLightest Supersymmetric ParticleStandard Model0103 physical sciencesHigh Energy Physics::ExperimentHiggsino010306 general physicsLeptonPhysical Review D
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Observation of Centrality-Dependent Acoplanarity for Muon Pairs Produced via Two-Photon Scattering in Pb+Pb Collisions at sNN=5.02  TeV with the ATLA…

2018

This Letter presents a measurement of γγ→μ^{+}μ^{-} production in Pb+Pb collisions recorded by the ATLAS detector at the Large Hadron Collider at sqrt[s_{NN}]=5.02  TeV with an integrated luminosity of 0.49  nb^{-1}. The azimuthal angle and transverse momentum correlations between the muons are measured as a function of collision centrality. The muon pairs are produced from γγ through the interaction of the large electromagnetic fields of the nuclei. The contribution from background sources of muon pairs is removed using a template fit method. In peripheral collisions, the muons exhibit a strong back-to-back correlation consistent with previous measurements of muon pair production in ultrap…

PhysicsLarge Hadron ColliderMuonPhotonLuminosity (scattering theory)Physics::Instrumentation and Detectors010308 nuclear & particles physicsScatteringGeneral Physics and Astronomy01 natural sciencesAcoplanarityNuclear physicsPair production13. Climate action0103 physical sciencesPhysics::Accelerator PhysicsHigh Energy Physics::ExperimentImpact parameterNuclear Experiment010306 general physicsPhysical Review Letters
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CP Properties of Higgs Boson Interactions with Top Quarks in the tt¯H and tH Processes Using H→γγ with the ATLAS Detector

2020

A study of the charge conjugation and parity (CP) properties of the interaction between the Higgs boson and top quarks is presented. Higgs bosons are identified via the diphoton decay channel (H→γγ), and their production in association with a top quark pair (tt[over ¯]H) or single top quark (tH) is studied. The analysis uses 139  fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of sqrt[s]=13  TeV with the ATLAS detector at the Large Hadron Collider. Assuming a CP-even coupling, the tt[over ¯]H process is observed with a significance of 5.2 standard deviations. The measured cross section times H→γγ branching ratio is 1.64_{-0.36}^{+0.38}(stat)_{-0.14}^{+0.17}(sys) …

PhysicsQuarkTop quarkParticle physicsLarge Hadron ColliderBranching fractionGeneral Physics and AstronomyParity (physics)7. Clean energy01 natural sciences0103 physical sciencesHiggs bosonCP violationHigh Energy Physics::ExperimentNuclear Experiment010306 general physicsBosonPhysical Review Letters
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Measurement of Azimuthal Anisotropy of Muons from Charm and Bottom Hadrons in pp Collisions at s=13  TeV with the ATLAS Detector

2020

The elliptic flow of muons from the decay of charm and bottom hadrons is measured in pp collisions at sqrt[s]=13  TeV using a data sample with an integrated luminosity of 150  pb^{-1} recorded by the ATLAS detector at the LHC. The muons from heavy-flavor decay are separated from light-hadron decay muons using momentum imbalance between the tracking and muon spectrometers. The heavy-flavor decay muons are further separated into those from charm decay and those from bottom decay using the distance-of-closest-approach to the collision vertex. The measurement is performed for muons in the transverse momentum range 4-7 GeV and pseudorapidity range |η|<2.4. A significant nonzero elliptic anisotro…

PhysicsMuonLarge Hadron ColliderPhysics::Instrumentation and DetectorsHigh Energy Physics::PhenomenologyElliptic flowHadronGeneral Physics and Astronomy01 natural sciencesNuclear physicsPseudorapidity0103 physical sciencesQuark–gluon plasmaPhysics::Accelerator PhysicsHigh Energy Physics::ExperimentRapidityImpact parameterNuclear Experiment010306 general physicsPhysical Review Letters
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Search for bottom-squark pair production in pp collision events at s=13  TeV with hadronically decaying τ -leptons, b -jets, and missing transverse m…

2021

A search for pair production of bottom squarks in events with hadronically decaying τ-leptons, b-tagged jets, and large missing transverse momentum is presented. The analyzed dataset is based on proton-proton collisions at s=13 TeV delivered by the Large Hadron Collider and recorded by the ATLAS detector from 2015 to 2018, and corresponds to an integrated luminosity of 139 fb-1. The observed data are compatible with the expected Standard Model background. Results are interpreted in a simplified model where each bottom squark is assumed to decay into the second-lightest neutralino χ 20 and a bottom quark, with χ 20 decaying into a Higgs boson and the lightest neutralino χ 10. The search focu…

PhysicsParticle physicsLarge Hadron Collider010308 nuclear & particles physicsPhysics beyond the Standard ModelHigh Energy Physics::Phenomenology01 natural sciencesBottom quarkStandard ModelPair production0103 physical sciencesNeutralinoHiggs bosonHigh Energy Physics::Experiment010306 general physicsLeptonPhysical Review D
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Search for the Higgs boson decays H → ee and H → eμ in pp collisions at s=13TeV with the ATLAS detector

2020

Searches for the Higgs boson decays H -> ee and H -> e mu are performed using data corresponding to an integrated luminosity of 139 fb(-1) collected with the ATLAS detector in pp collisions a ...

PhysicsNuclear and High Energy PhysicsParticle physicsLuminosity (scattering theory)Physics::Instrumentation and Detectors010308 nuclear & particles physicsAtlas detectorHigh Energy Physics::Phenomenology7. Clean energy01 natural sciencesSearch for the Higgs bosonmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesHiggs bosonmedicineHigh Energy Physics::Experiment010306 general physicsPhysics Letters B
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Search for invisible Higgs boson decays in vector boson fusion at s=13TeV with the ATLAS detector

2019

We report a search for Higgs bosons that are produced via vector boson fusion and subsequently decay into invisible particles. The experimental signature is an energetic jet pair with invariant mass of O(1)TeV and O(100)GeV missing transverse momentum. The analysis uses 36.1 fb −1 of pp collision data at s=13TeV recorded by the ATLAS detector at the LHC. In the signal region the 2252 observed events are consistent with the background estimation. Assuming a 125GeV scalar particle with Standard Model cross sections, the upper limit on the branching fraction of the Higgs boson decay into invisible particles is 0.37 at 95% confidence level where 0.28 was expected. This limit is interpreted in H…

PhysicsNuclear and High Energy PhysicsParticle physicsLarge Hadron Collider010308 nuclear & particles physicsBranching fractionHigh Energy Physics::PhenomenologyScalar boson01 natural sciences7. Clean energyStandard ModelVector boson0103 physical sciencesHiggs bosonHigh Energy Physics::ExperimentInvariant mass010306 general physicsBosonPhysics Letters B
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Measurement of the tt¯ production cross section in the τ+jets final state in pp collisions at s=8  TeV using the ATLAS detector

2017

A measurement of the inclusive pp -> t (t) over bar + X production cross section in the tau + jets final state using only the hadronic decays of the tau lepton is presented. The measurement is p ...

PhysicsTop quarkParticle physicsLarge Hadron Collider010308 nuclear & particles physicsAtlas detectorHigh Energy Physics::PhenomenologyHadron01 natural sciencesNuclear physicsPair production0103 physical sciencesHiggs bosonHigh Energy Physics::ExperimentResummation010306 general physicsLeptonPhysical Review D
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Search for a heavy charged boson in events with a charged lepton and missing transverse momentum from pp collisions at s=13  TeV with the ATLAS detec…

2019

A search for a heavy charged-boson resonance decaying into a charged lepton (electron or muon) and a neutrino is reported. A data sample of 139  fb−1 of proton-proton collisions at √s=13  TeV collected with the ATLAS detector at the LHC during 2015–2018 is used in the search. The observed transverse mass distribution computed from the lepton and missing transverse momenta is consistent with the distribution expected from the Standard Model, and upper limits on the cross section for pp→W′→lν are extracted (l=e or μ). These vary between 1.3 pb and 0.05 fb depending on the resonance mass in the range between 0.15 and 7.0 TeV at 95% confidence level for the electron and muon channels combined. …

PhysicsParticle physicsGauge bosonLarge Hadron ColliderMuon010308 nuclear & particles physicsHigh Energy Physics::Phenomenology01 natural sciencesPair production0103 physical sciencesTransverse massHigh Energy Physics::ExperimentNeutrino010306 general physicsLeptonBosonPhysical Review D
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Test of CP invariance in vector-boson fusion production of the Higgs boson in the H → ττ channel in proton–proton collisions at s=13TeV with the ATLA…

2020

A test of CP invariance in Higgs boson production via vector-boson fusion is performed in the H → ττ decay channel. This test uses the Optimal Observable method and is carried out using 36.1 fb−1 of √s = 13 TeV proton–proton collision data collected by the ATLAS experiment at the LHC. Contributions from CP-violating interactions between the Higgs boson and electroweak gauge bosons are described by an effective field theory, in which the parameter ˜ d governs the strength of CP violation. No sign of CP violation is observed in the distributions of the Optimal Observable, and ˜ d is constrained to the interval [−0.090, 0.035] at the 68% confidence level (CL), compared to an expected interval …

PhysicsNuclear and High Energy PhysicsGauge bosonParticle physicsLarge Hadron Collider010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyATLAS experimentElectroweak interaction01 natural sciencesVector bosonStandard Model0103 physical sciencesHiggs bosonCP violationHigh Energy Physics::Experiment010306 general physicsPhysics Letters B
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Search for Heavy Higgs Bosons Decaying into Two Tau Leptons with the ATLAS Detector Using pp Collisions at s=13  TeV

2020

A search for heavy neutral Higgs bosons is performed using the LHC Run 2 data, corresponding to an integrated luminosity of 139  fb^{-1} of proton-proton collisions at sqrt[s]=13  TeV recorded with the ATLAS detector. The search for heavy resonances is performed over the mass range 0.2-2.5 TeV for the τ^{+}τ^{-} decay with at least one τ-lepton decaying into final states with hadrons. The data are in good agreement with the background prediction of the standard model. In the M_{h}^{125} scenario of the minimal supersymmetric standard model, values of tanβ>8 and tanβ>21 are excluded at the 95% confidence level for neutral Higgs boson masses of 1.0 and 1.5 TeV, respectively, where tanβ is the…

PhysicsParticle physicsLarge Hadron ColliderHigh Energy Physics::PhenomenologyGeneral Physics and Astronomy01 natural sciences7. Clean energyStandard Modelmedicine.anatomical_structurePair productionAtlas (anatomy)0103 physical sciencesmedicineHiggs bosonHigh Energy Physics::Experiment010306 general physicsLeptonMinimal Supersymmetric Standard ModelBosonPhysical Review Letters
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Observation of Electroweak Production of a Same-Sign W Boson Pair in Association with Two Jets in pp Collisions at s=13  TeV with the ATLAS Detector

2019

This Letter presents the observation and measurement of electroweak production of a same-sign W boson pair in association with two jets using 36.1  fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of sqrt[s]=13  TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed in the detector fiducial phase-space region, defined by the presence of two same-sign leptons, electron or muon, and at least two jets with a large invariant mass and rapidity difference. A total of 122 candidate events are observed for a background expectation of 69±7 events, corresponding to an observed signal significance of 6.5 standard deviations. The measured fiducial s…

PhysicsParticle physicsLarge Hadron ColliderMuonElectroweak interactionGeneral Physics and Astronomy01 natural sciences0103 physical sciencesHigh Energy Physics::ExperimentRapidityInvariant massNuclear Experiment010306 general physicsEnergy (signal processing)BosonLeptonPhysical Review Letters
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Measurements of tt¯ differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pp collisions at s=13  TeV usin…

2018

Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and t (t) over bar system kinematic observables using proton-proton collis ...

Quantum chromodynamicsQuarkPhysicsTop quarkParticle physics010308 nuclear & particles physicsHigh Energy Physics::LatticeHigh Energy Physics::PhenomenologyNuclear TheoryHadronStrong interactionPerturbative QCDObservable01 natural sciencesmedicine.anatomical_structureAtlas (anatomy)0103 physical sciencesPhysics::Atomic and Molecular ClustersmedicineHigh Energy Physics::Experiment010306 general physicsPhysical Review D
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Search for Dark Matter Produced in Association with a Dark Higgs Boson Decaying into W±W∓ or ZZ in Fully Hadronic Final States from s=13  TeV pp Coll…

2021

Several extensions of the Standard Model predict the production of dark matter particles at the LHC. An uncharted signature of dark matter particles produced in association with VV=W^{±}W^{∓} or ZZ pairs from a decay of a dark Higgs boson s is searched for using 139  fb^{-1} of pp collisions recorded by the ATLAS detector at a center-of-mass energy of 13 TeV. The s→V(qq[over ¯])V(qq[over ¯]) decays are reconstructed with a novel technique aimed at resolving the dense topology from boosted VV pairs using jets in the calorimeter and tracking information. Dark Higgs scenarios with m_{s}>160  GeV are excluded.

PhysicsParticle physicsTop quarkLarge Hadron ColliderHigh Energy Physics::PhenomenologyDark matterGeneral Physics and Astronomy01 natural sciences7. Clean energyGalaxyStandard ModelHidden sector0103 physical sciencesHiggs bosonHigh Energy Physics::Experiment010306 general physicsBosonPhysical Review Letters
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Search for the standard model Higgs boson produced in association with a vector boson and decaying into a tau pair inppcollisions ats=8  TeVwith the …

2016

A search for the standard model Higgs boson produced in association with a vector boson with the decay H -> tau tau is presented. The data correspond to 20.3 fb(-1) of integrated luminosity from proton-proton collisions at root s = 8 TeV recorded by the ATLAS experiment at the LHC during 2012. The data agree with the background expectation, and 95% confidence-level upper limits are placed on the cross section of this process. The observed (expected) limit, expressed in terms of the signal strength mu= sigma/sigma(SM) for m(H) = 125 GeV, is mu < 5.6 (3.7). The measured value of the signal strength is mu = 2.3 +/- 1.6.

PhysicsParticle physicsLarge Hadron Collider010308 nuclear & particles physicsAtlas (topology)Atlas detectorATLAS experimentSigma01 natural sciencesVector bosonNuclear physicsMassless particle0103 physical sciencesHiggs bosonHigh Energy Physics::Experiment010306 general physicsPhysical Review D
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Measurement of prompt photon production in sNN=8.16 TeV p + Pb collisions with ATLAS

2019

The inclusive production rates of isolated, prompt photons in p+Pb collisions at sNN=8.16 TeV are studied with the ATLAS detector at the Large Hadron Collider using a dataset with an integrated luminosity of 165 nb −1 recorded in 2016. The cross-section and nuclear modification factor RpPb are measured as a function of photon transverse energy from 20 GeV to 550 GeV and in three nucleon–nucleon centre-of-mass pseudorapidity regions, (−2.83,−2.02) , (−1.84,0.91) , and (1.09,1.90) . The cross-section and RpPb values are compared with the results of a next-to-leading-order perturbative QCD calculation, with and without nuclear parton distribution function modifications, and with expectations b…

PhysicsNuclear and High Energy PhysicsPhotonLarge Hadron Collider010308 nuclear & particles physicsScatteringPerturbative QCDParton7. Clean energy01 natural sciencesNuclear physicsDistribution functionPseudorapidity0103 physical sciencesHigh Energy Physics::ExperimentRapidityNuclear Experiment010306 general physicsPhysics Letters B
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Measurement of the production cross section for a Higgs boson in association with a vector boson in the H → WW⁎ → ℓνℓν channel in pp collisions at s=…

2019

A measurement of the Higgs boson production cross sections via associated WH and ZH production using H -> WW* -> l nu l nu decays, where l stands for either an electron or a muon, is presente ...

PhysicsNuclear and High Energy PhysicsParticle physicsLarge Hadron ColliderMuonPhysics::Instrumentation and Detectors010308 nuclear & particles physicsAtlas detectorHigh Energy Physics::PhenomenologyElectron01 natural sciencesVector boson0103 physical sciencesHiggs bosonHigh Energy Physics::Experiment010306 general physicsPhysics Letters B
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Search for low-mass resonances decaying into two jets and produced in association with a photon using pp collisions at s=13 TeV with the ATLAS detect…

2019

A search is performed for localised excesses in dijet mass distributions of low-dijet-mass events produced in association with a high transverse energy photon. The search uses up to 79.8 fb−1 of LHC proton–proton collisions collected by the ATLAS experiment at a centre-of-mass energy of 13 TeV during 2015–2017. Two variants are presented: one which makes no jet flavour requirements and one which requires both jets to be tagged as b-jets. The observed mass distributions are consistent with multi-jet processes in the Standard Model. The data are used to set upper limits on the production cross-section for a benchmark Z′ model and, separately, on generic Gaussian-shape contributions to the mas…

PhysicsNuclear and High Energy PhysicsPhotonLarge Hadron Collider010308 nuclear & particles physicsAtlas detectorAtlas (topology)ATLAS experiment7. Clean energy01 natural sciencesNuclear physicsTransverse plane0103 physical sciencesHigh Energy Physics::Experiment010306 general physicsLow MassPhysics Letters B
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Latest Developments and Results of Radiation Tolerance CMOS Sensors with Small Collection Electrodes

2020

The development of radiation hard Depleted Monolithic Active Pixel Sensors (DMAPS) targets the replacement of hybrid pixel detectors to meet radiation hardness requirements of at least 1.5e16 1 MeV neq/cm2 for the HL-LHC and beyond. DMAPS were designed and tested in the TJ180 nm TowerJazz CMOS imaging technology with small electrodes pixel designs. This technology reduces costs and provides granularity of 36.4x36.4 um2 with low power operation (1 uW/pixel), low noise of ENC < 20 e-, a small collection electrode (3 um) and fast signal response within 25 ns bunch crossing. This contribution will present the latest developments after the MALTA and Mini-MALTA sensors. It will illustrate the imp…

noiseParticle tracking detectors ; Radiation-hard detectors ; Electronic detector readout concepts ; CMOS sensors ; Monolithic active pixel sensorsMaterials science010308 nuclear & particles physicsbusiness.industryintegrated circuitelectrode01 natural sciencesCMOSRadiation toleranceefficiency0103 physical sciencesElectrodeHardware_INTEGRATEDCIRCUITSelectronics: readoutOptoelectronicssemiconductor detector[PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det]Detectors and Experimental Techniquescontrol system010306 general physicsbusiness
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Two-particle azimuthal correlations in photonuclear ultraperipheral Pb+Pb collisions at 5.02 TeV with ATLAS

2021

We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina, YerPhI, Armenia, ARC, Australia, BMWFW and FWF, Austria, ANAS, Azerbaijan, SSTC, Belarus, CNPq and FAPESP, Brazil, NSERC, NRC, and CFI, Canada, CERN and ANID, Chile, CAS, MOST, and NSFC, China, COLCIENCIAS, Colombia, MSMT CR, MPO CR, and VSC CR, Czech Republic, DNRF and DNSRC, Denmark, IN2P3-CNRS and CEA-DRF/IRFU, France, SRNSFG, Georgia, BMBF, HGF, and MPG, Germany, GSRT, Greece, RGC and Hong Kong SAR, China, ISF and Benoziyo Center, Israel, INFN, Italy, MEXT and JSPS, Japan, CNR…

Systemgap [rapidity]heavy ion: scattering:Kjerne- og elementærpartikkelfysikk: 431 [VDP]Performanceangular correlation: long-rangeHadronMonte Carlo method01 natural sciencesHigh Energy Physics - ExperimentSubatomär fysikHigh Energy Physics - Experiment (hep-ex)PpCollisionscorrelation function: two-particleSubatomic Physics[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex]Nuclear Experiment (nucl-ex)Nuclear ExperimentNuclear Experimentcalorimeter: forward spectrometerSettore FIS/01Physicsangular correlation: two-particletwo-particle [correlation function]Large Hadron Collider4. EducationATLAS experimentHeavy-Ion CollisionsMonte Carlo [numerical calculations]ATLASCalorimeterforward spectrometer [calorimeter]CERN LHC Coll:Nuclear and elementary particle physics: 431 [VDP]medicine.anatomical_structureMultiplicityflowPseudorapidityDistributionsLhcnumerical calculations: Monte CarloParticle Physics - Experimentcharged particle: tracks530 PhysicscollectiveFOS: Physical sciencesLHC ATLAS High Energy Physicstransverse momentum[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]Relativistic heavy ionscharged particle: multiplicityNuclear physicsmultiplicity [charged particle]scattering [heavy ion]Atlas (anatomy)long-range [angular correlation]0103 physical sciencesmedicineFluctuationsNuclear Physics - Experimentddc:5305020 GeV-cms/nucleonHigh Energy Physicsperipheral010306 general physicshadron hadron: interactioninteraction [hadron hadron]LHC; Particle Physics; Photonuclear interactionstwo-particle [angular correlation]tracks [charged particle]010308 nuclear & particles physicsFísicaDetectorMultiplicity (mathematics)boundary conditionrapidity: gapcorrelationExperimental High Energy Physicsexperimental resultsModelPhysical Review C
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