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Paul Jackson

Bio: Paul Jackson is an academic researcher from University of Adelaide. The author has contributed to research in topics: Large Hadron Collider & Higgs boson. The author has an hindex of 141, co-authored 1372 publications receiving 93464 citations. Previous affiliations of Paul Jackson include University of Rostock & Politehnica University of Bucharest.


Papers
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Georges Aad1, Alexander Kupco2, Peter Davison3, Samuel Webb4  +2904 moreInstitutions (215)
TL;DR: In this paper, a measurement of the complete set of angular coefficients A0−7 describing these distributions in the Z-boson Collins-Soper frame was presented, which correspond to 20.3 fb−1 of pp collisions at s=8 TeV, collected by the ATLAS detector at the CERN LHC.
Abstract: The angular distributions of Drell-Yan charged lepton pairs in the vicinity of the Z-boson mass peak probe the underlying QCD dynamics of Z-boson production. This paper presents a measurement of the complete set of angular coefficients A0−7 describing these distributions in the Z-boson Collins-Soper frame. The data analysed correspond to 20.3 fb−1 of pp collisions at s=8 TeV, collected by the ATLAS detector at the CERN LHC. The measurements are compared to the most precise fixed-order calculations currently available (O(αs2)) and with theoretical predictions embedded in Monte Carlo generators. The measurements are precise enough to probe QCD corrections beyond the formal accuracy of these calculations and to provide discrimination between different parton-shower models. A significant deviation from the (O(αs2)) predictions is observed for A0 − A2. Evidence is found for non-zero A5,6,7, consistent with expectations.[Figure not available: see fulltext.]

76 citations

Journal ArticleDOI
Georges Aad1, Brad Abbott2, Jalal Abdallah3, Ovsat Abdinov4  +2868 moreInstitutions (191)
TL;DR: A measurement of the average number of charged particles inside jets using 20.3 fb of data recorded with the ATLAS detector in dijet events using quark and gluon jet fractions and the resulting charged-particle multiplicity is compared to several models.
Abstract: The number of charged particles inside jets is a widely used discriminant for identifying the quark or gluon nature of the initiating parton and is sensitive to both the perturbative and non-pertur ...

76 citations

Journal ArticleDOI
TL;DR: The term "warlord" has become an ugly, detrimental expression, evoking brutality, racketeering and terrorism as mentioned in this paper, and the demonisation of the Taliban and the elevation of the former warlords of the opposition to the rather more grandiose sounding "Northern Alliance" implies that the term 'warlord' is synonymous with anarchy, violence and a breakdown in civilised values.
Abstract: Warlord is a label that currently besets us on all fronts. The 2001–2002 military action in Afghanistan is illustrative of the West's ambivalent view of armed factions in the developing world in general. The demonisation of the Taliban and the elevation of the former ‘warlords’ of the opposition to the rather more grandiose sounding ‘Northern Alliance’, at once formalising the hitherto informal nature of the warlord system, implies that the term ‘warlord’ is synonymous with anarchy, violence and a breakdown in civilised values. ‘Warlord’ has become an ugly, detrimental expression, evoking brutality, racketeering and terrorism. Analysts referring to violence across developing countries routinely refer to ‘new wars’ and ‘post-modern’ conflict, and yet the language used to describe these phenomena is usually pre-modern (medievalism, baronial rule, new feudalism). This article outlines some examples of historical warlords and draws out the common issues. In particular it emphasises the fact that warlords have...

76 citations

Journal ArticleDOI
Georges Aad1, Brad Abbott2, Jalal Abdallah3, Ovsat Abdinov4  +2846 moreInstitutions (191)
TL;DR: In this article, a search for direct pair production of the supersymmetric partner of the top quark, decaying via a scalar tau to a nearly massless gravitino, has been performed using 20 fb(-1) of proton-proton collision data at root s = 8 TeV.
Abstract: A search for direct pair production of the supersymmetric partner of the top quark, decaying via a scalar tau to a nearly massless gravitino, has been performed using 20 fb(-1) of proton-proton collision data at root s = 8 TeV. The data were collected by the ATLAS experiment at the LHC in 2012. Top squark candidates are searched for in events with either two hadronically decaying tau leptons, one hadronically decaying tau and one light lepton, or two light leptons. No significant excess over the Standard Model expectation is found. Exclusion limits at 95 % confidence level are set as a function of the top squark and scalar tau masses. Depending on the scalar tau mass, ranging from the 87 GeV LEP limit to the top squark mass, lower limits between 490 and 650 GeV are placed on the top squark mass within the model considered.

75 citations

Journal ArticleDOI
Georges Aad1, Brad Abbott2, J. Abdallah3, A. A. Abdelalim4  +3035 moreInstitutions (179)
TL;DR: In this article, the first measurement of the W + jets cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC with the ATLAS detector was reported.

75 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: In this paper, the authors examined the change in the goodness-of-fit index (GFI) when cross-group constraints are imposed on a measurement model and found that the change was independent of both model complexity and sample size.
Abstract: Measurement invariance is usually tested using Multigroup Confirmatory Factor Analysis, which examines the change in the goodness-of-fit index (GFI) when cross-group constraints are imposed on a measurement model. Although many studies have examined the properties of GFI as indicators of overall model fit for single-group data, there have been none to date that examine how GFIs change when between-group constraints are added to a measurement model. The lack of a consensus about what constitutes significant GFI differences places limits on measurement invariance testing. We examine 20 GFIs based on the minimum fit function. A simulation under the two-group situation was used to examine changes in the GFIs (ΔGFIs) when invariance constraints were added. Based on the results, we recommend using Δcomparative fit index, ΔGamma hat, and ΔMcDonald's Noncentrality Index to evaluate measurement invariance. These three ΔGFIs are independent of both model complexity and sample size, and are not correlated with the o...

10,597 citations

Journal ArticleDOI
01 Apr 1988-Nature
TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

9,929 citations