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142 papers found.
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Measurements of top quark spin observables in \( t\overline{t} \) events using dilepton final states in \( \sqrt{s}=8 \) TeV pp collisions with the ATLAS detector

Measurements of top quark spin observables in \( t\overline{t} \) events are presented based on 20.2 fb−1 of \( \sqrt{s}=8 \) TeV proton-proton collisions recorded with the ATLAS detector at the LHC. The analysis is performed in the dilepton final state, characterised by the presence of two isolated leptons (electrons or muons). There are 15 observables, each sensitive to a...

Measurements of charge and CP asymmetries in b-hadron decays using top-quark events collected by the ATLAS detector in pp collisions at \( \sqrt{s}=8 \) TeV

Same- and opposite-sign charge asymmetries are measured in lepton+jets \( t\overline{t} \) events in which a b-hadron decays semileptonically to a soft muon, using data corresponding to an integrated luminosity of 20.3 fb−1 from proton-proton collisions at a centre-of-mass energy of \( \sqrt{s}=8 \) TeV collected with the ATLAS detector at the Large Hadron Collider at CERN. The...

A measurement of the calorimeter response to single hadrons and determination of the jet energy scale uncertainty using LHC Run-1 pp-collision data with the ATLAS detector

A measurement of the calorimeter response to isolated charged hadrons in the ATLAS detector at the LHC is presented. This measurement is performed with 3.2 nb\(^{-1}\) of proton–proton collision data at \(\sqrt{s}=7\) \(\,\mathrm{TeV}\) from 2010 and 0.1 nb\(^{-1}\) of data at \(\sqrt{s}=8\) \(\,\mathrm{TeV}\) from 2012. A number of aspects of the calorimeter response to isolated...

Measurements of ψ(2S) and X(3872) → J/ψπ + π − production in pp collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector

Differential cross sections are presented for the prompt and non-prompt production of the hidden-charm states X(3872) and ψ(2S), in the decay mode J/ψπ + π −, measured using 11.4 fb−1 of pp collisions at \( \sqrt{s}=8 \) TeV by the ATLAS detector at the LHC. The ratio of cross-sections X(3872)/ψ(2S) is also given, separately for prompt and non-prompt components, as well as the...

Measurement of the \(b\overline{b}\) dijet cross section in pp collisions at \(\sqrt{s} = 7\) TeV with the ATLAS detector

The dijet production cross section for jets containing a b-hadron (b-jets) has been measured in proton–proton collisions with a centre-of-mass energy of \(\sqrt{s} = 7\) TeV, using the ATLAS detector at the LHC. The data used correspond to an integrated luminosity of \(\mathrm 4.2\,\text {fb}^{-1}\). The cross section is measured for events with two identified b-jets with a...

Search for squarks and gluinos in events with hadronically decaying tau leptons, jets and missing transverse momentum in proton–proton collisions at \(\sqrt{s}=13\) TeV recorded with the ATLAS detector

A search for supersymmetry in events with large missing transverse momentum, jets, and at least one hadronically decaying tau lepton has been performed using 3.2 fb\(^{-1}\) of proton–proton collision data at \(\sqrt{s}=13{\mathrm {\ TeV}}\) recorded by the ATLAS detector at the Large Hadron Collider in 2015. Two exclusive final states are considered, with either exactly one or...

Study of hard double-parton scattering in four-jet events in pp collisions at \( \sqrt{s}=7 \) TeV with the ATLAS experiment

Inclusive four-jet events produced in proton-proton collisions at a centre-of-mass energy of \( \sqrt{s}=7 \) TeV are analysed for the presence of hard double-parton scattering using data corresponding to an integrated luminosity of 37.3 pb−1, collected with the ATLAS detector at the LHC. The contribution of hard double-parton scattering to the production of four-jet events is...

Search for the Higgs boson produced in association with a W boson and decaying to four b-quarks via two spin-zero particles in pp collisions at 13 TeV with the ATLAS detector

This paper presents a dedicated search for exotic decays of the Higgs boson to a pair of new spin-zero particles, \(H \rightarrow aa\), where the particle a decays to b-quarks and has a mass in the range of 20–60 GeV. The search is performed in events where the Higgs boson is produced in association with a \(W\) boson, giving rise to a signature of a lepton (electron or muon...

Search for bottom squark pair production in proton–proton collisions at \(\sqrt{s}=13\) TeV with the ATLAS detector

The result of a search for pair production of the supersymmetric partner of the Standard Model bottom quark (\(\tilde{b}^{}_{1} \)) is reported. The search uses 3.2 fb\(^{-1}\)  of pp collisions at \(\sqrt{s}=13\) TeV collected by the ATLAS experiment at the Large Hadron Collider in 2015. Bottom squarks are searched for in events containing large missing transverse momentum and...

Search for minimal supersymmetric standard model Higgs Bosons H / A and for a \(Z^{\prime }\) boson in the \(\tau \tau \) final state produced in pp collisions at \(\sqrt{s}= 13\) TeV with the ATLAS detector

A search for neutral Higgs bosons of the minimal supersymmetric standard model (MSSM) and for a heavneutral \(Z^{\prime }\) boson is performed using a data sample corresponding to an integrated luminosity of 3.2 fb\(^{-1}\) from proton–proton collisions at \(\sqrt{s} = 13\)  \({\mathrm {TeV}}\) recorded by the ATLAS detector at the LHC. The heavy resonance is assumed to decay to...

Charged-particle distributions at low transverse momentum in \(\sqrt{s} = 13\) TeV pp interactions measured with the ATLAS detector at the LHC

Measurements of distributions of charged particles produced in proton–proton collisions with a centre-of-mass energy of 13 TeV are presented. The data were recorded by the ATLAS detector at the LHC and correspond to an integrated luminosity of 151 \(\upmu\text{b}^{-1}\). The particles are required to have a transverse momentum greater than 100 MeV and an absolute pseudorapidity...

Measurement of jet activity in top quark events using the eμ final state with two b-tagged jets in pp collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector

Measurements of the jet activity in \( t\overline{t} \) events produced in proton-proton collisions at \( \sqrt{s}=8 \) TeV are presented, using 20.3 fb−1 of data collected by the ATLAS experiment at the Large Hadron Collider. The events were selected in the dilepton eμ decay channel with two identified b-jets. The numbers of additional jets for various jet transverse momentum (p...

Search for resonances in diphoton events at \( \sqrt{s}=13 \) TeV with the ATLAS detector

Searches for new resonances decaying into two photons in the ATLAS experiment at the CERN Large Hadron Collider are described. The analysis is based on proton-proton collision data corresponding to an integrated luminosity of 3.2 fb−1 at \( \sqrt{s}=13 \) TeV recorded in 2015. Two searches are performed, one targeted at a spin-2 particle of mass larger than 500 GeV, using Randall...

Searches for heavy diboson resonances in pp collisions at \( \sqrt{s}=13 \) TeV with the ATLAS detector

Searches for new heavy resonances decaying to WW, WZ, and ZZ bosons are presented, using a data sample corresponding to 3.2 fb−1 of pp collisions at \( \sqrt{s}=13 \) TeV collected with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting ννqq, ℓνqq, ℓℓqq and qqqq final states are combined, searching for an arrow-width resonance with mass between 500 and 3000...

Dark matter interpretations of ATLAS searches for the electroweak production of supersymmetric particles in \( \sqrt{s}=8 \) TeV proton-proton collisions

A selection of searches by the ATLAS experiment at the LHC for the electroweak production of SUSY particles are used to study their impact on the constraints on dark matter candidates. The searches use 20 fb−1 of proton-proton collision data at \( \sqrt{s}=8 \) TeV. A likelihood-driven scan of a five-dimensional effective model focusing on the gaugino-higgsino and Higgs sector of...

Search for squarks and gluinos in final states with jets and missing transverse momentum at \(\sqrt{s}\) =13 \({\mathrm{TeV}}\) with the ATLAS detector

A search for squarks and gluinos in final states containing hadronic jets, missing transverse momentum but no electrons or muons is presented. The data were recorded in 2015 by the ATLAS experiment in \(\sqrt{s}=13~{\mathrm{TeV}}\) proton–proton collisions at the Large Hadron Collider. No excess above the Standard Model background expectation was observed in 3.2 \(\mathrm{fb}^{-1...

Measurements of inclusive and differential fiducial cross-sections of \(t\bar{t}\gamma \) production in leptonic final states at \(\sqrt{s}=13~\text {TeV}\) in ATLAS

Inclusive and differential cross-sections for the production of a top-quark pair in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 36.1 \(\text{ fb }^{-1}\), collected by the ATLAS detector at the LHC in 2015 and 2016 at a centre-of-mass energy of 13 \(\text {TeV}\). The measurements are performed in single...

Measurement of the ratio of cross sections for inclusive isolated-photon production in pp collisions at \( \sqrt{s} \) = 13 and 8 TeV with the ATLAS detector

Abstract The ratio of the cross sections for inclusive isolated-photon production in pp collisions at centre-of-mass energies of 13 and 8 TeV is measured using the ATLAS detector at the LHC. The integrated luminosities of the 13 TeV and 8 TeV datasets are 3.2 fb−1 and 20.2 fb−1, respectively. The ratio is measured as a function of the photon transverse energy in different regions...

Search for Higgs boson pair production in the \( b\overline{b}W{W}^{*} \) decay mode at \( \sqrt{s} \) = 13 TeV with the ATLAS detector

Abstract A search for Higgs boson pair production in the \( b\overline{b}W{W}^{*} \) decay mode is performed in the \( b\overline{b}\mathit{\ell \nu qq} \) final state using 36.1 fb−1 of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. No evidence of events beyond the background expectation is found...

Measurement of the four-lepton invariant mass spectrum in 13 TeV proton-proton collisions with the ATLAS detector

Abstract A measurement of the four-lepton invariant mass spectrum is made with the ATLAS detector, using an integrated luminosity of 36.1 fb−1 of proton-proton collisions at \( \sqrt{s} \) = 13 TeV delivered by the Large Hadron Collider. The differential cross-section is measured for events containing two same-flavour opposite-sign lepton pairs. It exhibits a rich structure, with...