Observation of electroweak W±Z boson pair production in association with two jets in pp collisions at s=13 TeV with the ATLAS detector

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…

Search for high-mass dilepton resonances using 139 fb−1 of pp collision data collected at s=13 TeV with the ATLAS detector

A search for high-mass dielectron and dimuon resonances in the mass range of 250 GeV to 6 TeV is presented. The data were recorded by the ATLAS experiment in proton–proton collisions at a centre-of-mass energy of s=13 TeV during Run 2 of the Large Hadron Collider and correspond to an integrated luminosity of 139 fb −1 . A functional form is fitted to the dilepton invariant-mass distribution to model the contribution from background processes, and a generic signal shape is used to determine the significance of observed deviations from this background estimate. No significant deviation is observed and upper limits are placed at the 95% confidence level on the fiducial cross-section times bran…

Search for direct stau production in events with two hadronic τ -leptons in s=13  TeV pp collisions with the ATLAS detector

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…

Performance of the upgraded PreProcessor of the ATLAS Level-1 Calorimeter Trigger

The PreProcessor of the ATLAS Level-1 Calorimeter Trigger prepares the analogue trigger signals sent from the ATLAS calorimeters by digitising, synchronising, and calibrating them to reconstruct transverse energy deposits, which are then used in further processing to identify event features. During the first long shutdown of the LHC from 2013 to 2014, the central components of the PreProcessor, the Multichip Modules, were replaced by upgraded versions that feature modern ADC and FPGA technology to ensure optimal performance in the high pile-up environment of LHC Run 2. This paper describes the features of the newMultichip Modules along with the improvements to the signal processing achieved.

Search for a right-handed gauge boson decaying into a high-momentum heavy neutrino and a charged lepton in pp collisions with the ATLAS detector at s=13 TeV

A search for a right-handed gauge boson WR, decaying into a boosted right-handed heavy neutrino NR, in the framework of Left-Right Symmetric Models is presented. It is based on data from proton–proton collisions with a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the Large Hadron Collider during the years 2015, 2016 and 2017, corresponding to an integrated luminosity of 80 fb$^{−1}$. The search is performed separately for electrons and muons in the final state. A distinguishing feature of the search is the use of large-radius jets containing electrons. Selections based on the signal topology result in smaller background compared to the expected signal. No significant d…

Search for the Higgs boson decays H → ee and H → eμ in pp collisions at s=13TeV with the ATLAS detector

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 ...

Observation and Measurement of Forward Proton Scattering in Association with Lepton Pairs Produced via the Photon Fusion Mechanism at ATLAS

The observation of forward proton scattering in association with lepton pairs (eþe− þ p or μþμ− þ p) produced via photon fusion is presented. The scattered proton is detected by the ATLAS Forward Proton spectrometer, while the leptons are reconstructed by the central ATLAS detector. Proton-proton collision data recorded in 2017 at a center-of-mass energy of ffiffiffi s p ¼ 13 TeV are analyzed, corresponding to an integrated luminosity of 14.6 fb−1. A total of 57 (123) candidates in the ee þ p (μμ þ p) final state are selected, allowing the background-only hypothesis to be rejected with a significance exceeding 5 standard deviations in each channel. Proton-tagging techniques are introduced f…

Evidence for the production of three massive vector bosons with the ATLAS detector

A search for the production of three massive vector bosons in proton–proton collisions is performed using data at TeV recorded with the ATLAS detector at the Large Hadron Collider in the years 2015–2017, corresponding to an integrated luminosity of 79.8 fb−1. Events with two same-sign leptons ℓ (electrons or muons) and at least two reconstructed jets are selected to search for . Events with three leptons without any same-flavour opposite-sign lepton pairs are used to search for , while events with three leptons and at least one same-flavour opposite-sign lepton pair and one or more reconstructed jets are used to search for . Finally, events with four leptons are analysed to search for and .…

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 detector

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. …

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 ATLAS detector

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 …

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

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…

40(th) EASD Annual Meeting of the European Association for the Study of Diabetes : Munich, Germany, 5-9 September 2004

Search for heavy long-lived multicharged particles in proton-proton collisions at s=13  TeV using the ATLAS detector

A search for heavy long-lived multicharged particles is performed using the ATLAS detector at the LHC. Data with an integrated luminosity of 36.1 fb(-1) collected in 2015 and 2016 from proton-proto ...

Combination of searches for heavy resonances decaying into bosonic and leptonic final states using 36  fb−1 of proton-proton collision data at s=13  TeV with the ATLAS detector

Searches for new heavy resonances decaying into different pairings of W, Z, or Higgs bosons, as well as dirffiffiffiectly into leptons, are presented using a data sample corresponding to 36.1 fb(-1 ...

Addressing Patients Mobility through a Dynamic Performance Management perspective: the case of Sicily

Al giorno d'oggi molte regioni italiane sperimentano il fenomeno della mobilità sanitaria passiva, consistente nella tendenza dei loro residenti a rivolgersi ad altri sistemi sanitari regionali, spesso caratterizzati da miglior reputazione, per ricevere assistenza sanitaria. Poiché il Servizio Sanitario Italiano (SSN) è pubblico e regionalizzato, ogni governo regionale ha la responsabilità di prestare assistenza sanitaria ai propri residenti, garantendo al contempo ad ogni cittadino la libertà di essere curato fuori dalla propria giurisdizione, e compensando le regioni di destinazione per i servizi sanitari resi ai non residenti. Nonostante tale diritto di scelta sia un punto di forza del S…

Measurement of prompt photon production in sNN=8.16 TeV p + Pb collisions with ATLAS

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…

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=13 TeV with the ATLAS detector

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 ...

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 detector

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…