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A measurement of spin correlation in tt[over ¯] production is presented using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb^{-1}. The correlation between the top and antitop quark spins is extracted from dilepton tt[over ¯] events by using the difference in th

This article presents measurements of the t-channel single top-quark ((t) over bart) and top-antiquark (_ t) total production cross sections sdtq_ and sd _ tq_, their ratio Rt sdtq_= sd _ tq_, and a measurement of the inclusive production cross section sdtq _ _ tq_ in proton-proton collisions at ffiffiffi ps = 7 TeV at the LHC. Differential cross sections for the tq and _ tq processes are measured

A search for an excess of events with multiple high transverse momentum objects including charged leptons and jets is presented, using 20.3 fb(-1) of proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a centre-of-mass energy of root s = 8 TeV. No excess of events beyond Standard Model expectations is observed. Using extra-dimensional models for blac

A search has been performed, using the full 20.3 fb(-1) data sample of 8 TeV proton-proton collisions collected in 2012 with the ATLAS detector at the LHC, for photons originating from a displaced vertex due to the decay of a neutral long-lived particle into a photon and an invisible particle. The analysis investigates the diphoton plus missing transverse momentum final state, and is therefore mos

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 root 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 excluded at the 95% confid

A novel technique to identify and split clusters created by multiple charged particles in the ATLAS pixel detector using a set of artificial neural networks is presented. Such merged clusters are a common feature of tracks originating from highly energetic objects, such as jets. Neural networks are trained using Monte Carlo samples produced with a detailed detector simulation. This technique repla

The paper presents studies of Bose-Einstein Correlations (BEC) for pairs of like-sign charged particles measured in the kinematic range [Formula: see text] 100 MeV and [Formula: see text] 2.5 in proton collisions at centre-of-mass energies of 0.9 and 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. The integrated luminosities are approximately 7 [Formula: see text]b[Formula: see te

Double-differential three-jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of [Formula: see text] using the ATLAS detector at the large hadron collider. The measurements are presented as a function of the three-jet mass [Formula: see text], in bins of the sum of the absolute rapidity separations between the three leading jets [Formula: see text]. In

This article reports on a search for dark matter pair production in association with bottom or top quarks in [Formula: see text] of [Formula: see text] collisions collected at [Formula: see text] TeV by the ATLAS detector at the LHC. Events with large missing transverse momentum are selected when produced in association with high-momentum jets of which one or more are identified as jets containing

This Letter presents a search at the LHC for s-channel single top-quark production in proton-proton collisions at a centre-of-mass energy of 8 TeV. The analyzed data set was recorded by the ATLAS detector and corresponds to an integrated luminosity of 20.3 fb(-1). Selected events contain one charged lepton, large missing transverse momentum and exactly two b-tagged jets. A multivariate event class

This Letter presents a search for new resonances decaying to final states with a vector boson produced in association with a high transverse momentum photon, V gamma, with V = W(-> l nu) or Z(-> l(+)l(-)), where l = mu or mu. The measurements use 20.3fb(-1) of proton-proton collision data at a center-of-mass energy of root s = 8 TeV recorded with the ATLAS detector. No deviations from the Standard

A search is conducted for non-resonant new phenomena in dielectron and dimuon final states, originating from either contact interactions or large extra spatial dimensions. The LHC 2012 proton-proton collision dataset recorded by the ATLAS detector is used, corresponding to 20 fb(-1) at root s = 8 TeV. The dilepton invariant mass spectrum is a discriminating variable in both searches, with the cont

The inclusive top quark pair (t (t) over tilde) production cross-section sigma(t (t) over bar) has been measured in proton-proton collisions at root s = 7 TeV and root s = 8 TeV with the ATLAS experiment at the LHC, using t (t) over bar events with an opposite-charge e mu pair in the final state. The measurement was performed with the 2011 7 TeV dataset corresponding to an integrated luminosity of

A measurement of the total pp cross section at the LHC at root s = 7 TeV is presented. In a special run with high-beta* beam optics, an integrated luminosity of 80 mu b(-1) was accumulated in order to measure the differential elastic cross section as a function of the Mandelstam momentum transfer variable t. The measurement is performed with the ALFA sub-detector of ATLAS. Using a fit to the diffe

This Letter reports the observation of a high transverse momentum Z -> b (b) over bar signal in proton-proton collisions at root s = 8TeVand the measurement of its production cross section. The data analysed were collected in 2012 with the ATLAS detector at the LHC and correspond to an integrated luminosity of 19.5 fb(-1). The Z -> b (b) over bar decay is reconstructed from a pair of b-tagged jets

A search for new charged massive gauge bosons, called W', is performed with the ATLAS detector at the LHC, in proton-proton collisions at a centre-of-mass energy of root s = 8 TeV, using a dataset corresponding to an integrated luminosity of 20.3 fb(-1). This analysis searches for W' bosons in the W' -> t (b) over tilde decay channel in final states with electrons or muons, using a multivariate me

A search for resonant WZ production in the l nu l'l' (l, l' = e, mu) decay channel using 20.3 fb(-1) of root s = 8 TeV pp collision data collected by the ATLAS experiment at LHC is presented. No significant deviation from the Standard Model prediction is observed and upper limits on the production cross sections of WZ resonances from an extended gauge model W' and from a simplified model of heavy

Measurements of charged-particle fragmentation functions of jets produced in ultra-relativistic nuclear collisions can provide insight into the modification of parton showers in the hot, dense medium created in the collisions. ATLAS has measured jets in root S-NN = 2.76 TeV Pb+Pb collisions at the LHC using a data set recorded in 2011 with an integrated luminosity of 0.14 nb(-1). Jets were reconst

This paper reports on a search for narrow resonances in diboson production in the [Formula: see text] final state using [Formula: see text] collision data corresponding to an integrated luminosity of [Formula: see text] fb[Formula: see text] collected at [Formula: see text] TeV with the ATLAS detector at the Large Hadron Collider. No significant excess of data events over the Standard Model expect

This paper presents cross sections for the production of a [Formula: see text] boson in association with jets, measured in proton-proton collisions at [Formula: see text] with the ATLAS experiment at the large hadron collider. With an integrated luminosity of [Formula: see text], this data set allows for an exploration of a large kinematic range, including jet production up to a transverse momentu