Advanced search    

Search: authors:"G. Aad"

356 papers found.
Use AND, OR, NOT, +word, -word, "long phrase", (parentheses) to fine-tune your search.

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...

Addendum to ‘Measurement of the \(t\bar{t}\) production cross-section using \(e\mu \) events with b-tagged jets in pp collisions at \(\sqrt{s}\) = 7 and 8 \(\,\mathrm{TeV}\) with the ATLAS detector’

The ATLAS measurement of the inclusive top quark pair (\(t\bar{t}\)) cross-section \(\sigma _{t\bar{t}}\) in proton–proton collisions at \(\sqrt{s}=8\) \(\,\mathrm{TeV}\) has been updated using the final 2012 luminosity calibration. The updated cross-section result is: $$\begin{aligned} \sigma _{t\bar{t}}= 242.9\pm 1.7\pm 5.5\pm 5.1\pm 4.2\,\mathrm pb, \end{aligned}$$where 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...

Test of CP invariance in vector-boson fusion production of the Higgs boson using the Optimal Observable method in the ditau decay channel with the ATLAS detector

A test of CP invariance in Higgs boson production via vector-boson fusion using the method of the Optimal Observable is presented. The analysis exploits the decay mode of the Higgs boson into a pair of \(\tau \) leptons and is based on 20.3 \(\mathrm{fb}^{-1}\) of proton–proton collision data at \(\sqrt{s}\) = 8 \(\,\mathrm{TeV}\) collected by the ATLAS experiment at the LHC...

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...

Performance of pile-up mitigation techniques for jets in \(pp\) collisions at \(\sqrt{s}=8\) TeV using the ATLAS detector

The large rate of multiple simultaneous proton–proton interactions, or pile-up, generated by the Large Hadron Collider in Run 1 required the development of many new techniques to mitigate the adverse effects of these conditions. This paper describes the methods employed in the ATLAS experiment to correct for the impact of pile-up on jet energy and jet shapes, and for the presence...

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...

Measurement of total and differential W + W − production cross sections in proton-proton collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector and limits on anomalous triple-gauge-boson couplings

The production of W boson pairs in proton-proton collisions at \( \sqrt{s}=8 \) TeV is studied using data corresponding to 20.3 fb−1 of integrated luminosity collected by the ATLAS detector during 2012 at the CERN Large Hadron Collider. The W bosons are reconstructed using their leptonic decays into electrons or muons and neutrinos. Events with reconstructed jets are not included...

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...

The performance of the jet trigger for the ATLAS detector during 2011 data taking

The performance of the jet trigger for the ATLAS detector at the LHC during the 2011 data taking period is described. During 2011 the LHC provided proton–proton collisions with a centre-of-mass energy of 7 TeV and heavy ion collisions with a 2.76 TeV per nucleon–nucleon collision energy. The ATLAS trigger is a three level system designed to reduce the rate of events from the 40...

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...