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Observation of four-top-quark production in the multilepton final state with th...
Castro, Nuno Filipe; Onofre, A.; ATLAS CollaborationThis paper presents the observation of four-top-quark (tt¯ tt¯) production in proton-proton collisions at the LHC. The analysis is performed using an integrated luminosity of 140 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 separ...
Search for new phenomena in multi-body invariant masses in events with at least...
Castro, Nuno Filipe; Onofre, A.; ATLAS CollaborationA search for resonances in events with at least one isolated lepton (e or μ) and two jets is performed using 139 fb −1 of s = 13 TeV proton–proton collision data recorded by the ATLAS detector at the LHC. Deviations from a smoothly falling background hypothesis are tested in three- and four-body invariant mass distributions constructed from leptons and jets, including jets identified as originating from bottom ...
Strong Constraints on Jet Quenching in Centrality-Dependent p+Pb Collisions at ...
Castro, Nuno Filipe; Onofre, A.; ATLAS CollaborationJet 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 p p and p + Pb collisions. In contrast, while jet quenching is observed in Pb +...
Search for a new scalar resonance in flavour-changing neutral-current top-quark...
Castro, Nuno Filipe; Onofre, A.; ATLAS CollaborationA search for flavour-changing neutral-current decays of a top quark into an up-type quark (either up or charm) and a light scalar particle X decaying into a bottom anti-bottom quark pair is presented. The search focuses on top-quark pair production where one top quark decays to qX, with X → bb¯ , and the other top quark decays according to the Standard Model, with the W boson decaying leptonically. The final st...
Inclusive-photon production and its dependence on photon isolation in pp collis...
Castro, Nuno Filipe; Onofre, A.; ATLAS CollaborationMeasurements of differential cross sections are presented for inclusive isolated-photon production in pp collisions at a centre-of-mass energy of 13 TeV provided by the LHC and using 139 fb −1 of data recorded by the ATLAS experiment. The cross sections are measured as functions of the photon transverse energy in different regions of photon pseudorapidity. The photons are required to be isolated by means of a f...
A search for new resonances in multiple final states with a high transverse mom...
Castro, Nuno Filipe; Onofre, A.; ATLAS CollaborationA generic search for resonances is performed with events containing a Z boson with transverse momentum greater than 100 GeV, decaying into e + e − or μ + μ −. The analysed data collected with the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider correspond to an integrated luminosity of 139 fb −1. Two invariant mass distributions are examined for a loca...
Roadmap on ferroelectric hafnia- and zirconia-based materials and devices
Silva, José Pedro Basto; Alcala, Ruben; Avci, Uygar E.; Barrett, Nick; Bégon-Lours, Laura; Borg, Mattias; Byun, Seungyong; Chang, Sou ChiFerroelectric hafnium and zirconium oxides have undergone rapid scientific development over the last decade, pushing them to the forefront of ultralow-power electronic systems. Maximizing the potential application in memory devices or supercapacitors of these materials requires a combined effort by the scientific community to address technical limitations, which still hinder their application. Besides their fav...
Observation of Single-Top-Quark Production in Association with a Photon Using t...
Castro, Nuno Filipe; Onofre, A.; ATLAS CollaborationThis Letter reports the observation of single top quarks produced together with a photon, which directly probes the electroweak coupling of the top quark. The analysis uses 139 fb^{-1} of 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. Requiring a photon with transverse momentum larger than 20 GeV and within the detector acceptance, the fiducial cross section...
Measurement of Suppression of Large-Radius Jets and Its Dependence on Substruct...
Castro, Nuno Filipe; Onofre, A.; ATLAS CollaborationThis letter presents a measurement of the nuclear modification factor of large-radius jets in Formula Presented Formula Presented collisions by the ATLAS experiment. The measurement is performed using Formula Presented and Formula Presented of Formula Presented and Formula Presented data, respectively. The large-radius jets are reconstructed with the anti-Formula Presented algorithm using a radius parameter of ...
Measurements of the suppression and correlations of dijets in Pb+Pb collisions ...
Castro, Nuno Filipe; Onofre, A.; ATLAS CollaborationStudies of the correlations of the two highest transverse momentum (leading) jets in individual Pb+Pb collision events can provide information about the mechanism of jet quenching by the hot and dense matter created in such collisions. In Pb+Pb and pp collisions at√sNN = 5.02 TeV, measurements of the leading dijet transverse momentum (pT) correlations are presented. Additionally, measurements in Pb+Pb collision...