7 research outputs found

    Measurement of the correlation between flow harmonics of different order in lead-lead collisions at √sNN = 2.76 TeV with the ATLAS detector

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    Correlations between the elliptic or triangular flow coefficients vm (m=2 or 3) and other flow harmonics vn (n=2 to 5) are measured using √sNN=2.76 TeV Pb+Pb collision data collected in 2010 by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 7 μb−1. The vm−vn correlations are measured in midrapidity as a function of centrality, and, for events within the same centrality interval, as a function of event ellipticity or triangularity defined in a forward rapidity region. For events within the same centrality interval, v3 is found to be anticorrelated with v2 and this anticorrelation is consistent with similar anticorrelations between the corresponding eccentricities, ε2 and ε3. However, it is observed that v4 increases strongly with v2, and v5 increases strongly with both v2 and v3. The trend and strength of the vm−vn correlations for n=4 and 5 are found to disagree with εm−εn correlations predicted by initial-geometry models. Instead, these correlations are found to be consistent with the combined effects of a linear contribution to vn and a nonlinear term that is a function of v22 or of v2v3, as predicted by hydrodynamic models. A simple two-component fit is used to separate these two contributions. The extracted linear and nonlinear contributions to v4 and v5 are found to be consistent with previously measured event-plane correlations

    Search for vectorlike B quarks in events with one isolated lepton, missing transverse momentum, and jets at √s = 8 TeV with the ATLAS detector

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    A search has been performed for pair production of heavy vectorlike down-type (B) quarks. The analysis explores the lepton-plus-jets final state, characterized by events with one isolated charged lepton (electron or muon), significant missing transverse momentum, and multiple jets. One or more jets are required to be tagged as arising from b quarks, and at least one pair of jets must be tagged as arising from the hadronic decay of an electroweak boson. The analysis uses the full data sample of pp collisions recorded in 2012 by the ATLAS detector at the LHC, operating at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb −1 . No significant excess of events is observed above the expected background. Limits are set on vectorlike B production, as a function of the B branching ratios, assuming the allowable decay modes are B → Wt/Zb/Hb. In the chiral limit with a branching ratio of 100% for the decay B → Wt, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 810 GeV (760 GeV). In the case where the vectorlike B quark has branching ratio values corresponding to those of an SU(2) singlet state, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 640 GeV (505 GeV). The same analysis, when used to investigate pair production of a colored, charge 5/3 exotic fermion T 5/3 , with subsequent decay T 5/3 → Wt, sets an observed (expected) 95% C.L. lower limit on the T 5/3 mass of 840 GeV (780 GeV)

    ATLAS Run 1 searches for direct pair production of third-generation squarks at the Large Hadron Collider

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    This paper reviews and extends searches for the direct pair production of the scalar supersymmetric partners of the top and bottom quarks in proton–proton collisions collected by the ATLAS collaboration during the LHC Run 1. Most of the analyses use 20 fb−1 of collisions at a centre-of-mass energy of s√=8 TeV, although in some case an additional 4.7 fb−1 of collision data at s√=7 TeV are used. New analyses are introduced to improve the sensitivity to specific regions of the model parameter space. Since no evidence of third-generation squarks is found, exclusion limits are derived by combining several analyses and are presented in both a simplified model framework, assuming simple decay chains, as well as within the context of more elaborate phenomenological supersymmetric models.An erratum to this article can be found at http://dx.doi.org/10.1140/epjc/s10052-016-3935-

    Promoting Research Activities and Management Reform in Universities : An Approach from Policy Sciences

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    Many commentators have insisted without empirical evidence that the heterogeneity of fuculty members promotes the research activities in universities. We have to examine whether or not this assertion would be valid and which element of heterogeneity may contribute to promoting research outputs. This article investigates the relationship between heterogeneity in educational background and research performance, then examines how the Science Research Grant has been allocated to faculties in economics. The result shows that the more heterogeneous faculty members are, the more the research outputs increase. The analysis also indicates that the research performance has been little considered in making decision for adoption while it has made significant effect on the amount of grant for the adopted subject

    Curriculum corruption? : On the place of subjects in secondary school curriculum making

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    The production of a W boson in association with a single charm quark is studied using 4.6 fb-1 of pp collision data at 1as = 7TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+-00.30 at Q2 = 1.9 GeV, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally the cross-section ratio \u3c3(W+ + c)/\u3c3(W- +c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s\u2013s quark asymmetry

    Physical activity during pregnancy through postpartum: A study of predictive and explanatory factors in a multi-ethnic population

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    The study objectives were to (a) describe steps and moderate-to-vigorous intensity physical activity (MVPA) from pregnancy and postpartum across ethnic groups, (b) test prognostic factors for early identification of pregnant women at risk of non-compliance with the guideline (=150 MVPA minutes/week), and (c) to explore the association between access to recreational areas and MVPA. Data originated from the Stork-Groruddalen Cohort Study (n=823). MVPA was monitored with a multi-sensor device in gestational week (GW) 15 and 28 and three months postpartum. Country of birth defined ethnicity. Data on access to recreational areas was obtained by geographic information systems and self-report. MVPA declined between GW 15 and 28, by which only 25% complied with the guideline. Four factors predicted guideline non-compliance (ethnic minority background, high body fat percentage, at least two previous births and few physically active friends). MVPA increased significantly for Western women between GW 28 and postpartum, while the increase was modest for ethnic minority women. Women with good access to recreational areas accumulated more MVPA minutes/day than women with limited access

    Aspects of neutron-spin echo spectroscopy at pulsed sources

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    The integrated elliptic flow of charged particles produced in Pb+Pb collisions at (Formula presented.)\ua0TeV\ua0has been measured with the ATLAS detector using data collected at the Large Hadron Collider. The anisotropy parameter, v2, was measured in the pseudorapidity range |\u3b7| 642.5 with the event-plane method. In order to include tracks with very low transverse momentum pT, thus reducing the uncertainty in v2 integrated over pT, a 1 \u3bcb-1 data sample recorded without a magnetic field in the tracking detectors is used. The centrality dependence of the integrated v2 is compared to other measurements obtained with higher pT thresholds. The integrated elliptic flow is weakly decreasing with |\u3b7|. The integrated v2 transformed to the rest frame of one of the colliding nuclei is compared to the lower-energy RHIC data
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