We present a novel approach to distributional-only, fully unsupervised, POS tagging, based on an adaptation of the EM algorithm for the estimation of a Gaussian mixture. In this approach, which we call Latent-Descript...
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This paper presents a novel approach to networked control systems (NCS) analysis and design that provides increased control performance for a set of control loops that exchange control data over the Controller Area Ne...
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This paper presents a novel approach to networked control systems (NCS) analysis and design that provides increased control performance for a set of control loops that exchange control data over the Controller Area Network (CAN). This is achieved by enabling the following functionality for each control loop: first, standard periodic messaging is guaranteed to ensure stability, and second, non-periodic additional messaging is added whenever the bus is idle in such a way that the aggregated control performance for all control loops is improved. The proposed approach, named Maximum Difference (MD) policy, is computable in a distributed manner, and is practically feasible (computationally efficient and CAN-implementable). We theoretically prove that the MD policy behaves better than static strategies. Simulation results complement the theoretical derivations and show that the MD policy outperforms static, random and Largest Error First policies.
The results of a search for pair production of the scalar partners of bottom quarks in 2.05 fb−1 of pp collisions at s=7 TeV using the ATLAS experiment are reported. Scalar bottom quarks are searched for in events w...
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The results of a search for pair production of the scalar partners of bottom quarks in 2.05 fb−1 of pp collisions at s=7 TeV using the ATLAS experiment are reported. Scalar bottom quarks are searched for in events with large missing transverse momentum and two jets in the final state, where both jets are identified as originating from a bottom quark. In an R-parity conserving minimal supersymmetric scenario, assuming that the scalar bottom quark decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits are obtained in the b˜1−χ˜10 mass plane such that for neutralino masses below 60 GeV scalar bottom masses up to 390 GeV are excluded.
The χb(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider at s=7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 ...
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The χb(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider at s=7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb−1, these states are reconstructed through their radiative decays to Υ(1S,2S) with Υ→μ+μ−. In addition to the mass peaks corresponding to the decay modes χb(1P,2P)→Υ(1S)γ, a new structure centered at a mass of 10.530±0.005(stat)±0.009(syst) GeV is also observed, in both the Υ(1S)γ and Υ(2S)γ decay modes. This structure is interpreted as the χb(3P) system.
This Letter describes a model-independent search for the production of new resonant states in photon+jet events in 2.11 fb−1 of proton-proton collisions at s=7 TeV. We compare the photon+jet mass distribution to a b...
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This Letter describes a model-independent search for the production of new resonant states in photon+jet events in 2.11 fb−1 of proton-proton collisions at s=7 TeV. We compare the photon+jet mass distribution to a background model derived from data and find consistency with the background-only hypothesis. Given the lack of evidence for a signal, we set 95% credibility level limits on generic Gaussian-shaped signals and on a benchmark excited-quark (q*) model, excluding 2 TeV Gaussian resonances with cross section times branching fraction times acceptance times efficiency near 5 fb and excluding q* masses below 2.46 TeV, respectively.
A measurement of the ZZ production cross section in proton-proton collisions at s=7 TeV using data corresponding to an integrated luminosity of 1.02 fb−1 recorded by the ATLAS experiment at the LHC is presented. Twe...
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A measurement of the ZZ production cross section in proton-proton collisions at s=7 TeV using data corresponding to an integrated luminosity of 1.02 fb−1 recorded by the ATLAS experiment at the LHC is presented. Twelve events containing two Z boson candidates decaying to electrons and/or muons are observed, with an expected background of 0.3±0.3(stat)−0.3+0.4(syst) events. The cross section measured in a phase-space region with good detector acceptance and for dilepton masses within the range 66 to 116 GeV is σZZ→ℓ+ℓ−ℓ+ℓ−fid=19.4−5.2+6.3(stat)−0.7+0.9(syst)±0.7(lumi) fb. The resulting total cross section for on-shell ZZ production, σZZtot=8.5−2.3+2.7(stat)−0.3+0.4(syst)±0.3(lumi) pb, is consistent with the standard model expectation of 6.5−0.2+0.3 pb calculated at the next-to-leading order in QCD. Limits on anomalous neutral triple gauge boson couplings are derived.
A search for new phenomena in tt¯ events with large missing transverse momentum in proton-proton collisions at a center-of-mass energy of 7 TeV is presented. The measurement is based on 1.04 fb−1 of data collect...
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A search for new phenomena in tt¯ events with large missing transverse momentum in proton-proton collisions at a center-of-mass energy of 7 TeV is presented. The measurement is based on 1.04 fb−1 of data collected with the ATLAS detector at the LHC. Contributions to this final state may arise from a number of standard model extensions. The results are interpreted in terms of a model where new top-quark partners are pair produced and each decay to an on-shell top (or antitop) quark and a long-lived undetected neutral particle. The data are found to be consistent with standard model expectations. A limit at 95% confidence level is set excluding a cross section times branching ratio of 1.1 pb for a top-partner mass of 420 GeV and a neutral particle mass less than 10 GeV. In a model of exotic fourth generation quarks, top-partner masses are excluded up to 420 GeV and neutral particle masses up to 140 GeV.
A search for the Higgs boson has been performed in the H→WW(*)→ℓ+νℓ−ν¯ channel (ℓ=e/μ) with an integrated luminosity of 2.05 fb−1 of pp collisions at s=7 TeV collected with the ATLAS detector at the Large ...
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A search for the Higgs boson has been performed in the H→WW(*)→ℓ+νℓ−ν¯ channel (ℓ=e/μ) with an integrated luminosity of 2.05 fb−1 of pp collisions at s=7 TeV collected with the ATLAS detector at the Large Hadron Collider. No significant excess of events over the expected background is observed and limits on the Higgs boson production cross section are derived for a Higgs boson mass in the range 110 GeV
A search is presented for production of a heavy up-type quark (t′) together with its antiparticle, assuming subsequent decay to a W boson and a b quark, t′t¯′→W+bW−b¯. The search is based on 1.04 fb−1 o...
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A search is presented for production of a heavy up-type quark (t′) together with its antiparticle, assuming subsequent decay to a W boson and a b quark, t′t¯′→W+bW−b¯. The search is based on 1.04 fb−1 of proton-proton collisions at s=7 TeV collected by the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in the lepton+jets final state, characterized by a high transverse momentum isolated electron or muon, high missing transverse momentum, and at least three jets. No significant excess of events above the background expectation is observed. A 95% C.L. lower limit of 404 GeV is set for the mass of the t′ quark.
A measurement of spin correlation in tt¯ production is reported using data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 2.1 fb−1. Candidate events are selected in th...
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A measurement of spin correlation in tt¯ production is reported using data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 2.1 fb−1. Candidate events are selected in the dilepton topology with large missing transverse energy and at least two jets. The difference in azimuthal angle between the two charged leptons in the laboratory frame is used to extract the correlation between the top and antitop quark spins. In the helicity basis the measured degree of correlation corresponds to Ahelicity=0.40−0.08+0.09, in agreement with the next-to-leading-order standard model prediction. The hypothesis of zero spin correlation is excluded at 5.1 standard deviations.
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