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.

Search for new phenomena in events with same-charge leptons and b-jets in pp collisions at √s=13 TeV with the ATLAS detector

Abstract: A search for new phenomena in events with two same-charge leptons or three leptons and jets identified as originating from b-quarks in a data sample of 361 fb−1 of pp collisions at s√=13 TeV recorded by the ATLAS detector at the Large Hadron Collider is reported No significant excess is found and limits are set on vector-like quark, four-top-quark, and same-sign top-quark pair production The observed (expected) 95% CL mass limits for a vector-like T- and B-quark singlet are mT > 098 (099) TeV and mB > 100 (101) TeV respectively Limits on the production of the vector-like T5/3-quark are also derived considering both pair and single production; in the former case the lower limit on the mass of the T5/3-quark is (expected to be) 119 (121) TeV The Standard Model four-top-quark production cross-section upper limit is (expected to be) 69 (29) fb Constraints are also set on exotic four-top-quark production models Finally, limits are set on same-sign top-quark pair production The upper limit on uu → tt production is (expected to be) 89 (59) fb for a mediator mass of 1 TeV, and a dark-matter interpretation is also derived, excluding a mediator of 3 TeV with a dark-sector coupling of 10 and a coupling to ordinary matter above 031

Measurement of the inclusive electron spectrum in charmless semileptonic B decays near the kinematic end point and determination of |Vub|

Abstract: We present a measurement of the inclusive electron spectrum in B → X_ueν decays near the kinematic limit for B → X_ceν transitions, using a sample of 88 × 10^6 BB pairs recorded by the BABAR detector at the Υ (4S resonance. Partial branching fraction measurements are performed in five overlapping intervals of the electron momentum; for the interval of 2.0 – 2.6 GeV/c we obtain ΔB (B → X_ueν) = (0.572 ± 0.041_(stat) ± 0.065_(syst)) × 10^(−3). Combining this result with shape function parameters extracted from BABAR measurements of moments of the inclusive photon spectrum in B → X_sγ decays and moments of the hadron-mass and lepton-energy spectra in B → X_clν decays we determine │Vub|= (4.44 ± 0.25 + 0.4_( exp−0.38SF) ± 0.22_(theory)) × 10^(−3). Here the first error represents the combined statistical and systematic experimental uncertainties of the partial branching fraction measurement, the second error refers to the uncertainty of the determination of the shape function parameters, and the third error is due to theoretical uncertainties in the QCD calculations.

Explaining broadband adoption in rural Australia: modes of reflexivity and the morphogenetic approach

Abstract: Universal fast broadband is currently being implemented by the Australian government. It is the largest single project in Australia's history. Represented as a nation-building exercise by the government and many public and private promoters, it is vilified by others as a massive waste of taxpayers' money. Ultimately the target of successful universal availability will require that metropolitan installations subsidize rural adoption. The take-up of these facilities, particularly in regional and remote areas, constitutes a complex, multifactorial scenario in which political, personal, and organizational decisions are shaped by physical, cultural, economic, and ideological elements. Critical realism is proposed here as an aid for examining the complex reality of rural adoption for communities and small businesses in the regions. This article highlights the importance of considering individual reflexivity in explaining the adoption decision and potential adoption barriers.

Measurement of the tt¯Z and tt¯W cross sections in proton-proton collisions at √s=13 TeV with the ATLAS detector

Abstract: A measurement of the associated production of a top-quark pair (tt) with a vector boson (W, Z) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented, using 36.1 fb-1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. Events are selected in channels with two same- or opposite-sign leptons (electrons or muons), three leptons or four leptons, and each channel is further divided into multiple regions to maximize the sensitivity of the measurement. The ttZ and ttW production cross sections are simultaneously measured using a combined fit to all regions. The best-fit values of the production cross sections are σttZ=0.95±0.08stat±0.10syst pb and σttW=0.87±0.13stat±0.14syst pb in agreement with the Standard Model predictions. The measurement of the ttZ cross section is used to set constraints on effective field theory operators which modify the ttZ vertex.

Search for supersymmetry in events with four or more leptons in √s =13 TeV pp collisions with ATLAS

Abstract: Results from a search for supersymmetry in events with four or more charged leptons (electrons, muons and taus) are presented. The analysis uses a data sample corresponding to 36.1 fb-1 of proton-proton collisions delivered by the Large Hadron Collider at s=13 TeV and recorded by the ATLAS detector. Four-lepton signal regions with up to two hadronically decaying taus are designed to target a range of supersymmetric scenarios that can be either enriched in or depleted of events involving the production and decay of a Z boson. Data yields are consistent with Standard Model expectations and results are used to set upper limits on the event yields from processes beyond the Standard Model. Exclusion limits are set at the 95% confidence level in simplified models of general gauge mediated supersymmetry, where Higgsino masses are excluded up to 295 GeV. In R-parity-violating simplified models with decays of the lightest supersymmetric particle to charged leptons, lower limits of 1.46, 1.06, and 2.25 TeV are placed on wino, slepton and gluino masses, respectively. © 2018 CERN.

I and i

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 …

Evaluating Goodness-of-Fit Indexes for Testing Measurement Invariance

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...

Phd by thesis

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