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Measurements of inclusive jet production are performed in pp and Pb+Pb collisions at sqrt[s_{NN}]=2.76 TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 and 0.14 nb^{-1}, respectively. The jets are identified with the anti-k_{t} algorithm with R=0.4, and the spectra are measured over the kinematic range of jet transverse momentum 32
This paper reports a measurement of the W+b-jets (W+b+X and W+b (b) over bar +X) production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. These results are based on data corresponding to an integrated luminosity of 4.6 fb(-1), collected with the ATLAS detector. Cross-sections are presented as a function of jet multiplicity and of the transverse momentum
This Letter presents a search for quantum black-hole production using 20.3 fb(-1) of data collected with the ATLAS detector in pp collisions at the LHC at root s = 8 TeV. The quantum black holes are assumed to decay into a final state characterized by a lepton (electron or muon) and a jet. In either channel, no event with a lepton-jet invariant mass of 3.5 TeV or more is observed, consistent with
Measurements of the production of jets of particles in association with a Z boson in pp collisions at root s = 7 TeV are presented, using data corresponding to an integrated luminosity of 4.6 fb(-1) collected by the ATLAS experiment at the Large Hadron Collider. Inclusive and differential jet cross sections in Z events, with Z decaying into electron or muon pairs, are measured for jets with transv
This Letter presents measurements of the polarization of the top quark in top-antitop quark pair events, using 4: 7 fb(-1) of proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at root s = 7 TeV. Final states containing one or two isolated leptons ( electrons or muons) and jets are considered. Two measurements of alpha P-l, the product of the leptonic spin-a
This paper presents a search for a new heavy particle produced in association with a top or antitop quark. Two models in which the new heavy particle is a color singlet or a color triplet are considered, decaying, respectively, to (t)over-barq or tq, leading to a resonance within the t(t)over-bar + jets signature. The full 2011 ATLAS pp collision data set from the LHC (4.7 fb(-1)) is used to searc
The production of a W boson decaying to ev or mu v in association with a W or Z boson decaying to two jets is studied using 4.6 fb(-1) of proton-proton collision data at root s = 7 TeV recorded with the ATLAS detector at the LHC. The combined WW + WZ cross section is measured with a significance of 3.4 sigma and is found to be 68 +/- 7 (stat.) +/- 19 (syst.) pb, in agreement with the Standard Mode
A search is presented for dark matter pair production in association with a W or Z boson in pp collisions representing 20.3 fb(-1) of integrated luminosity at root s = 8 TeV using data recorded with the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet with the jet mass consistent with a W or Z boson, and with large missing transverse momentum are analyzed. The data are consi
This Letter presents a search for pair production of heavy down-type quarks decaying via b' -> Wt in the lepton + jets channel, as b'(b) over bar' -> W(-)tW(+)(t) over bar -> b (b) over barW(+)W(-)W(+)W- -> l(+/-) nu b (b) over barq (q) over barq (q) over barq ($) over barq. In addition to requiring exactly one lepton, large missing transverse momentum, and at least six jets, the invariant mass of
Charged-particle spectra obtained in Pb+Pb interactions at root s(NN) = 2.76TeV and pp interactions at root s(NN) = 2.76TeV with the ATLAS detector at the LHC are presented, using data with integrated luminosities of 0.15 nb(-1) and 4.2 pb(-1), respectively, in a wide transverse momentum (0.5 < p(T) < 150 GeV) and pseudorapidity (vertical bar eta vertical bar < 2) range. For Pb+Pb collisions, the
Results of a search for new phenomena in events with an energetic photon and large missing transverse momentum in proton-proton collisions at root s = 7 TeV are reported. Data collected by the ATLAS experiment at the LHC corresponding to an integrated luminosity of 4.6 fb(-1) are used. Good agreement is observed between the data and the standard model predictions. The results are translated into e
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 describes measurements of the sum of the transverse energy of particles as a function of particle pseudorapidity, eta, in proton-proton collisions at a centre-of-mass energy, root s = 7 TeV using the ATLAS detector at the Large Hadron Collider. The measurements are performed in the region \eta\ < 4.8 for two event classes: those requiring the presence of particles with a low transverse
Measurements of the branching ratios of top quark decays into leptons and jets using events with t (t) over bar ( top antitop) pairs are reported. Events were recorded with the ATLAS detector at the LHC in pp collisions at a center-of-mass energy of 7 TeV. The collected data sample corresponds to an integrated luminosity of 4.6 fb(-1). The measured top quark branching ratios agree with the Standar
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
Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb(-1) of pp collision data at root s = 7 TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from >= 6 to >= 9 jets. No evidence is foun
Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of TeV. The analysis is performed in the H -> gamma gamma decay channel using 20.3 fb(-1) of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assum
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
The ATLAS detector at the LHC is used to search for high-mass states, such as heavy charged gauge bosons (W'), decaying to a charged lepton (electron or muon) and a neutrino. Results are presented based on the analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.7 fb(-1). No excess beyond Standard Model expectations is observed. A W' with Seq
This letter reports the results of a search for top and bottom squarks from gluino pair production in 4.7 fb(-1) of pp collisions at root s = 7 TeV using the ATLAS detector at the LHC. The search is performed in events with large missing transverse momentum and at least three jets identified as originating from a b-quark. Exclusion limits are presented for a variety of gluino-mediated models with
