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303 papers found.
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Search for direct top squark pair production in events with a Higgs or Z boson, and missing transverse momentum in \( \sqrt{s}=13 \) TeV pp collisions with the ATLAS detector

A search for direct top squark pair production resulting in events with either a same-flavour opposite-sign dilepton pair with invariant mass compatible with a Z boson or a pair of jets compatible with a Standard Model (SM) Higgs boson (h) is presented. Requirements on the missing transverse momentum, together with additional selections on leptons, jets, jets identified as ...

Fiducial, total and differential cross-section measurements of t-channel single top-quark production in pp collisions at 8 TeV using data collected by the ATLAS detector

Detailed measurements of t-channel single top-quark production are presented. They use 20.2 fb\(^{-1}\) of data collected by the ATLAS experiment in proton–proton collisions at a centre-of-mass energy of 8 TeV at the LHC. Total, fiducial and differential cross-sections are measured for both top-quark and top-antiquark production. The fiducial cross-section is measured with a ...

Jet reconstruction and performance using particle flow with the ATLAS Detector

This paper describes the implementation and performance of a particle flow algorithm applied to 20.2 fb\(^{-1}\) of ATLAS data from 8 TeV proton–proton collisions in Run 1 of the LHC. The algorithm removes calorimeter energy deposits due to charged hadrons from consideration during jet reconstruction, instead using measurements of their momenta from the inner tracker. This improves ...

Measurements of electroweak \(Wjj \) production and constraints on anomalous gauge couplings with the ATLAS detector

Measurements of the electroweak production of a W boson in association with two jets at high dijet invariant mass are performed using \(\sqrt{s} =\) 7 and 8 \(\text {TeV}\) proton–proton collision data produced by the Large Hadron Collider, corresponding respectively to 4.7 and 20.2 fb\(^{-1}\) of integrated luminosity collected by the ATLAS detector. The measurements are sensitive ...

Topological cell clustering in the ATLAS calorimeters and its performance in LHC Run 1

The reconstruction of the signal from hadrons and jets emerging from the proton–proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In ...

Studies of Zγ production in association with a high-mass dijet system in pp collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector

The production of a Z boson and a photon in association with a high-mass dijet system is studied using 20.2 fb−1 of proton-proton collision data at a centre-of-mass energy of \( \sqrt{s}=8 \) TeV recorded with the ATLAS detector in 2012 at the Large Hadron Collider. Final states with a photon and a Z boson decaying into a pair of either electrons, muons, or neutrinos are analysed. ...

Measurement of multi-particle azimuthal correlations in pp, p + Pb and low-multiplicity Pb + Pb collisions with the ATLAS detector

Multi-particle cumulants and corresponding Fourier harmonics are measured for azimuthal angle distributions of charged particles in \(pp\) collisions at \(\sqrt{s}\) = 5.02 and 13 TeV and in \(p\) + Pb collisions at \(\sqrt{s_{_\text {NN}}}\) = 5.02 TeV, and compared to the results obtained for low-multiplicity \(\mathrm{Pb}~+~\mathrm{Pb}\) collisions at \(\sqrt{s_{_\text {NN}}}\) ...

Search for dark matter at \(\sqrt{s}=13~\mathrm{TeV}\) in final states containing an energetic photon and large missing transverse momentum with the ATLAS detector

Results of a search for physics beyond the Standard Model in events containing an energetic photon and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. As the number of events observed in data, corresponding to an integrated luminosity of 36.1 fb\(^{-1}\) of proton–proton collisions at a centre-of-mass energy of ...

Precision measurement and interpretation of inclusive \(W^+\) , \(W^-\) and \(Z/\gamma ^*\) production cross sections with the ATLAS detector

High-precision measurements by the ATLAS Collaboration are presented of inclusive \(W^+ \rightarrow \ell ^+\nu \), \(W^- \rightarrow \ell ^-\bar{\nu }\) and \(Z/\gamma ^* \rightarrow \ell \ell \) (\(\ell =e,\mu \)) Drell–Yan production cross sections at the LHC. The data were collected in proton–proton collisions at \(\sqrt{s} = 7\,\text {TeV}\) with an integrated luminosity of ...

Measurements of the production cross section of a \(Z\) boson in association with jets in pp collisions at \(\sqrt{s} = 13\) TeV with the ATLAS detector

Measurements of the production cross section of a \(Z\) boson in association with jets in proton–proton collisions at \(\sqrt{s} = 13\) TeV are presented, using data corresponding to an integrated luminosity of 3.16 fb\(^{-1}\) collected by the ATLAS experiment at the CERN Large Hadron Collider in 2015. Inclusive and differential cross sections are measured for events containing a ...

Measurement of jet fragmentation in Pb+Pb and pp collisions at \(\sqrt{{s_\mathrm{NN}}} = 2.76\) TeV with the ATLAS detector at the LHC

The distributions of transverse momentum and longitudinal momentum fraction of charged particles in jets are measured in Pb+Pb and pp collisions with the ATLAS detector at the LHC. The distributions are measured as a function of jet transverse momentum and rapidity. The analysis utilises an integrated luminosity of 0.14 nb\(^{-1}\) of Pb+Pb data and 4.0 pb\(^{-1}\) of pp data ...

Measurements of top-quark pair differential cross-sections in the \(e\mu \) channel in pp collisions at \(\sqrt{s} = 13\) TeV using the ATLAS detector

This article presents measurements of \(t\bar{t}\) differential cross-sections in a fiducial phase-space region, using an integrated luminosity of 3.2 fb\(^{-1}\) of proton–proton data at a centre-of-mass energy of \(\sqrt{s} = 13\) TeV recorded by the ATLAS experiment at the LHC in 2015. Differential cross-sections are measured as a function of the transverse momentum and absolute ...

Performance of the ATLAS trigger system in 2015

During 2015 the ATLAS experiment recorded \(3.8\,{\mathrm{fb}}^{-1}\) of proton–proton collision data at a centre-of-mass energy of \(13\,{\mathrm{TeV}}\). The ATLAS trigger system is a crucial component of the experiment, responsible for selecting events of interest at a recording rate of approximately 1 kHz from up to 40 MHz of collisions. This paper presents a short overview of ...

Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of \(\sqrt{s} = 8\) TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide ...

Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using \( \sqrt{s}=8 \) TeV proton-proton collision data

A search for squarks and gluinos in final states containing high-p T jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in \( \sqrt{s}=8 \) TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and ...

Search for new particles in events with one lepton and missing transverse momentum in pp collisions at \( \sqrt{s} \) = 8 TeV with the ATLAS detector

This paper presents a search for new particles in events with one lepton (electron or muon) and missing transverse momentum using 20.3 fb−1 of proton-proton collision data at \( \sqrt{s} \) = 8 TeV recorded by the ATLAS experiment at the Large Hadron Collider. No significant excess beyond Standard Model expectations is observed. A W ′ with Sequential Standard Model couplings is ...

Measurement of the production cross-section of ψ(2S) → J/ψ(→μ + μ − )π + π − in pp collisions at \( \sqrt{s} \) = 7 TeV at ATLAS

The prompt and non-prompt production cross-sections for ψ(2S) mesons are measured using 2.1 fb−1 of pp collision data at a centre-of-mass energy of 7 TeV recorded by the ATLAS experiment at the LHC. The measurement exploits the ψ(2S) → J/ψ(→ μ + μ − )π + π − decay mode, and probes ψ(2S) mesons with transverse momenta in the range 10 ≤ p T 100 GeV and rapidity |y| 2.0. The results ...

Electron reconstruction and identification efficiency measurements with the ATLAS detector using the 2011 LHC proton–proton collision data

Many of the interesting physics processes to be measured at the LHC have a signature involving one or more isolated electrons. The electron reconstruction and identification efficiencies of the ATLAS detector at the LHC have been evaluated using proton–proton collision data collected in 2011 at \(\sqrt{s}= 7\) TeV and corresponding to an integrated luminosity of 4.7 fb \(^{-1}\) . ...

Performance of algorithms that reconstruct missing transverse momentum in \(\sqrt{s}\) = 8 TeV proton–proton collisions in the ATLAS detector

The reconstruction and calibration algorithms used to calculate missing transverse momentum (\(E_{\text {T}}^{\text {miss}}\) ) with the ATLAS detector exploit energy deposits in the calorimeter and tracks reconstructed in the inner detector as well as the muon spectrometer. Various strategies are used to suppress effects arising from additional proton–proton interactions, called ...

Measurement of jet activity produced in top-quark events with an electron, a muon and two b-tagged jets in the final state in pp collisions at \(\sqrt{s}=13\) TeV with the ATLAS detector

Measurements of jet activity in top-quark pair events produced in proton–proton collisions are presented, using 3.2 fb\(^{-1}\) of pp collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS experiment at the Large Hadron Collider. Events are chosen by requiring an opposite-charge \(e\mu \) pair and two b-tagged jets in the final state. The normalised differential ...