Making publics visible through digital traces has recently generated interest by practitioners of public engagement and scholars within the field of digital methods. This paper presents an experiment in moving such methods into critical proximity with political practice and discusses how digital visualizations of topical debates become appropriated by actors and hardwired into existing ecologies of publics and politics. Through an experiment in rendering a specific data-public visible, it shows how the interplay between diverse conceptions of the public as well (...) as the specific platforms and data invoked, resulted in a situated affordance-space that allowed specific renderings take shape, while disadvantaging others. Furthermore, it argues that several accepted tropes in the literatures of digital methods ended up being problematic guidelines in this space. Among these is the prescription to shown heterogeneity by pushing back at established media logics. (shrink)

Digital social analytics is a subset of Big Data methods that is used to understand the social environment in which people and organizations have to act. This paper presents an analysis of eight projects that are experimenting with the use of these methods for various purposes. It shows that two specific technological features influence the work with such methods in all the cases. The first concerns the need to distribute choices about the structure of data to third-party actors and the (...) second concerns the need to balance machine intelligence and human intuition when automating the analysis. These features set specific conditions for knowledge production, and the paper identifies two opposite approaches for engaging with each of these conditions. These features and approaches are finally combined into a two-dimensional affordance space that illustrates how there is flexibility in the way project leaders interact with the features of the data environment. It thereby also shows how digital social analytics come to have different affordances for different projects. (shrink)

This paper presents an analysis of interviews, focus groups and workshops with employees in the technical administration in the municipality of Copenhagen in the year after it won a prestigious Smart City award. The administration is interpreted as a ‘most likely’ to succeed in translating the idealised version of the smart city into a workable bureaucratic practice. Drawing on the work of Orlikowski and Gash, the empirical analysis identifies and describes two incongruent ‘technological frames’ that illustrates different ways of making (...) sense of data and the smart city within this single organisational unit. One is called the experimentalist’s credo and it is characterised by inspiration from the development of an Internet of Things as well as a readiness to learn from the open source community in software development. The other is called the data-owners vocation and it is characterised by a more situated approach that interprets data as strategic and political. It is argued that the existence of these frames provides two insights relevant for the literature on smart cities. First, they illustrate that one should be careful not to reify the smart city as a phenomenon that can be criticised in generic terms. Second, they suggest that even if there exists a transition toward the implementation of a technocratic smart city paradigm across public administrations, this paradigm is not unique in its focus on markets and evidence in governance. (shrink)

The era of ‘big data’ studies and computational social science has recently given rise to a number of realignments within and beyond the social sciences, where otherwise distinct data formats – digital, numerical, ethnographic, visual, etc. – rub off and emerge from one another in new ways. This article chronicles the collaboration between a team of anthropologists and sociologists, who worked together for one week in an experimental attempt to combine ‘big’ transactional and ‘small’ ethnographic data formats. Our collaboration is (...) part of a larger cross-disciplinary project carried out at the Danish Technical University, where high-resolution transactional data from smartphones allows for recordings of social networks amongst a freshman class. With a parallel deployment of ethnographic fieldwork among the DTU students, this research set-up raises a number of questions concerning how to assemble disparate ‘data-worlds’ and to what epistemological and political effects? To address these questions, a specific social event – a lively student party – was singled out from the broader DTU dataset. Our experimental collaboration used recordings of Bluetooth signals between students’ phones to visualize the ebb and flow of social intensities at the DTU party, juxtaposing these with ethnographic field-notes on shifting party atmospheres. Tracing and reflecting on the process of combining heterogeneous data, the article offers a concrete case of how a ‘stitching together’ of digital and ethnographic data-worlds might take place. (shrink)

Berg, J. Buñuels dagdröm.--Bergström, L. Pessimismens konsekvenser.--Furberg, M. Möjliga teser hos Johannes Climacus.--Halldén, S. Teckenrelationen och språkreglernas juridik.--Hedenius, I. Ett argument mot den rättsfilosofiska domstolsrealismen.--Mates, B. Om Platons argument "den tredje människan."--Marc-Wogau, K. Kant om lögnen.--Næss, A. Om filosofiske projekter som forener empirisk semantikk og metafysisk spekulasjon.--Ofstad, H. Får nazister lettere magesår enn humanister?--Prawitz, D. Om moraliska och logiska satsers sanning.--Stenius, E. Om Descartes' psykofysiska modell.--Tranøy, K. E. Filosofenes etiske ansvar.--Wright, G. H. von. En filosof ser på filosofien.

ABSTRACT‘Green’ concerns about nature, the environment or the climate have traditionally been juxtaposed with concerns about economic growth or job creation. Recently, however, a new type of conflict has appeared, in which different green concerns, for instance regarding mitigation of climate change and protection of landscape qualities, seem to collide. These environmental conflicts have so far received little scholarly attention. This article addresses the issue by a study of national and in particular local news media discussion on the construction of (...) wind turbines in Denmark, bringing together research traditions from environmental communication, discourse analysis, and place studies. Analytically, the study employs the notion of topos as the key meaning unit, referring to the premises upon which an argument is based. In addition to the empirical findings, the study points to methodological potential of the concept of topos to integrate qualitative and quantitative approaches within a discourse studie... (shrink)

We report general and consensus results of a survey administered to a defined population of economic science academics in Mexico. Our results include insights on economic opinions, scientific aspects of economics, scientific activities, countries' economic performances and methodological orientation. Our outcomes show areas of consensus which, at least partially, are consistent with findings in previous studies. Comparisons between our results and those of other studies suggest that consensus could be constant over time and that economics academics in Mexico seems to (...) show similar levels of skepticism about the importance of rationality assumption as those in other latitudes. (shrink)

The deadly attacks on a public meeting and on a Jewish citizen in Copenhagen in February 2015 have given rise to a vast amount of public discussion and interpretation of the events themselves, their background, their causes, their significance, and their repercussions. During these discussions, various conceptions of publicness and public space have been articulated. Indeed, one may view the killings as a ‘critical discourse moment’ in which a range of discourses have been employed to help interpret, understand, and deal (...) with what happened. In several of these discourses, conceptions of publicness play a central part. This article sets out to investigate the conceptions of publicness that were articulated in the Danish public spheres following the attacks. The article maps out some of the key different and partly contradictory notions of publicness that the reactions to the killings brought to the fore. The investigation thus focuses on the articulation of normative expectations and ideals of public spheres, on the limitations and restrictions that were acknowledged, and on the main societal problems and national contexts to which publicness was viewed as related. The analysis will cover national newspapers and center on the discursive resources of the media elite in early responses to the attacks, for example in editorials, or comments by writers, academics, debaters, and intellectuals. (shrink)

Martha Nussbaum’s capabilities approach is today one of the most influential theories of justice. In her earlier works on the capabilities approach, Nussbaum only applies it to humans, but in later works she extends the capabilities approach to include sentient animals. Contrary to Nussbaum’s own view, some scholars, for example, David Schlosberg, Teea Kortetmäki and Daniel L. Crescenzo, want to extend the capabilities approach even further to include collective entities, such as species and ecosystems. Though I think we have strong (...) reasons for preserving ecosystems and species within the capabilities approach, there are several problems with ascribing capabilities to them, especially if we connect it with the view that species and ecosystems are subjects of justice. These problems are partly a consequence of the fact that an ascription of capabilities to species and ecosystems needs to be based on an overlapping consensus between different comprehensive doctrines, in accordance with the framework of political liberalism on which the capabilities approach builds. First, the ascription of capabilities to species and ecosystems presupposes the controversial standpoint that they are objectively existing entities. Second, the ascription of capabilities to ecosystems and species and the view that they are subjects of justice is justified by claiming that they have integrity and agency, but these characteristics have different meanings when applied to collective entities and humans, respectively. Third, the view that species and ecosystems are subjects of justice seems to require the controversial assumption that they have interests of their own, which differ from the interests of the sentient beings that are part of them. However, even if we do not ascribe capabilities to species and ecosystems and regard them as subjects of justice, there are still strong reasons to protect them within the capabilities approach, as the preservation of ecosystems and species is an important precondition for many human and animal capabilities. (shrink)

Essai sur l'évolution de la pensée du philosophe, et de son approche du concept d'égalité, égalité intellectuelle, égalité politique et égalité sensible. Electre 2018.

The appeal to expert opinion is an argument form that uses the verdict of an expert to support a position or hypothesis. A previous scheme-based treatment of the argument form is formalized within a Bayesian network that is able to capture the critical aspects of the argument form, including the central considerations of the expert's expertise and trustworthiness. We propose this as an appropriate normative framework for the argument form, enabling the development and testing of quantitative predictions as to how (...) people evaluate this argument, suggesting that such an approach might be beneficial to argumentation research generally. We subsequently present two experiments as an example of the potential for future research in this vein, demonstrating that participants' quantitative ratings of the convincingness of a proposition that has been supported with an appeal to expert opinion were broadly consistent with the predictions of the Bayesian model. (shrink)

J. L. Austin's claim that language ‘used not seriously’ is ‘parasitic’ upon ‘normal use’ has proved a puzzle to literary scholars, who have often taken this to mean that they are not allowed to apply the insights of speech-act theory to their own object of research. This article explores how, when read together, Michel Serres’ definition of the parasite as a ‘thermal exciter’ and Deleuze's concept of ‘minor literature’ bring out the hidden potential inherent in Austin's claim. More specifically, the (...) article argues that Austin's reference to literature as a parasitic entity might become a promising conceptual gift, allowing us to generate a new model for approaching the world-shaping potential of literary texts. (shrink)

This paper is a discussion of the concept ‘student active forms of learning’. It aims not at conclusions, but at a perspicuous representation—a map for future navigation and understanding of the concept. From the perspective of philosophy of education, I characterize and discuss issues relating to student active learning in the paper. The context for my discussion is higher education. Further, I contrast student active learning to a form of learning that is allegedly passive, the lecture, which traditionally is the (...) main form of learning in higher education. I proceed by assessing arguments in favor of the two forms by way of a philosophical analysis, a main component of which is transparent exposition. Positive conclusions are not the main concern, but rather to demonstrate possibilities. Still, two results of the discussions in the paper are noteworthy: ‘student active learning’ is a weak construct, it being too general or even contradictory; the lecture is not passive, and a student-centered education, consequently, should not be construed as a dismissal of lecturing. (shrink)

Linkage of population-based administrative data is a valuable tool for combining detailed individual-level information from different sources for research. While not a substitute for classical studies based on primary data collection, analyses of linked administrative data can answer questions that require large sample sizes or detailed data on hard-to-reach populations, and generate evidence with a high level of external validity and applicability for policy making. There are unique challenges in the appropriate research use of linked administrative data, for example with (...) respect to bias from linkage errors where records cannot be linked or are linked together incorrectly. For confidentiality and other reasons, the separation of data linkage processes and analysis of linked data is generally regarded as best practice. However, the ‘black box’ of data linkage can make it difficult for researchers to judge the reliability of the resulting linked data for their required purposes. This article aims to provide an overview of challenges in linking administrative data for research. We aim to increase understanding of the implications of the data linkage environment and privacy preservation; the linkage process itself and linkage quality and potential bias in linked data. We draw on examples from a number of countries to illustrate a range of approaches for data linkage in different contexts. (shrink)

In the present study we investigated the stability and malleability of cadets’ definitions of success (mastery and performance goal orientations) contextualized within a certain motivational climate (mastery and performance climates). Based on data from three military academies, the results revealed that cadets’ goal orientations and their perceptions of the motivational climate remained relatively stable throughout the two years of study across three time-points. We also found that a mastery climate predicted individual mastery orientation, and that a performance climate predicted individual (...) performance orientation. These findings contribute to achievement goal theory by clarifying the importance of considering goal orientation contextualized within a certain motivational climate over time. Implications for future research and practice are discussed. (shrink)

Går det an å kunne mer enn man har lært? Finnes det ferdigheter og kompetanser som er generelle? Kategorien «generell kompetanse» i Nasjonalt kvalifikasjonsrammeverk for livslang læring forutsetter at svarene på disse spørsmålene er «ja». I denne artikkelen argumenterer jeg for at svaret ikke er så enkelt.

Bayesian probability has recently been proposed as a normative theory of argumentation. In this article, we provide a Bayesian formalisation of the ad Hitlerum argument, as a special case of the ad hominem argument. Across three experiments, we demonstrate that people's evaluation of the argument is sensitive to probabilistic factors deemed relevant on a Bayesian formalisation. Moreover, we provide the first parameter-free quantitative evidence in favour of the Bayesian approach to argumentation. Quantitative Bayesian prescriptions were derived from participants' stated subjective (...) probabilities (Experiments 1 and 2), as well as from frequency information explicitly provided in the experiment (Experiment 3). Participants' stated evaluations of the convincingness of the argument were well matched to these prescriptions. (shrink)

“One who elects to serve mankind by taking the law into his own hands thereby demonstrates his conviction that his own ability to determine policy is superior to democratic decision making. [Defendants’] professed unselfish motivation, rather than a justification, actually identifies a form of arrogance which organized society cannot tolerate.” Those were the words of Justice Harris L. Hartz at the sentencing hearing of three nuns convicted of trespassing and vandalizing government property to demonstrate against U.S. foreign policy. Citizens engaging (...) in civil disobedience are indeed at times accused of being arrogant because they apparently think their own political judgment is superior to that of the democratic majority. This paper examines and evaluates the claim that dissenters are epistemically arrogant. Contrary to the dominant viewpoint in the literature, I argue that epistemic arrogance involves inflating the epistemic worth of one’s view. Indeed, the most plausible charge against civil dissenters consists of two claims: (A) civil dissenters have a higher degree of rational certainty in P than is warranted, and (B) civil dissenters use a method of expression that requires a higher level of rational certainty than is warranted in the propositions that their political view is right and the injustice they fight is substantial. I argue that civil disobedience does not necessarily involve epistemic arrogance. Whether an act of civil disobedience evinces epistemic arrogance has to be determined on a case-by-case basis depending on the extent to which each dissenter lives up to (A) and (B). (shrink)

© 2016, CERN for the benefit of the.The luminosity determination for the ATLAS detector at the LHC during pp collisions at s= 8 TeV in 2012 is presented. The evaluation of the luminosity scale is performed using several luminometers, and comparisons between these luminosity detectors are made to assess the accuracy, consistency and long-term stability of the results. A luminosity uncertainty of δL/ L= ± 1.9 % is obtained for the 22.7fb-1 of pp collision data delivered to ATLAS at s= (...) 8 TeV in 2012. (shrink)

Emerging trends in the workforce point to the necessity of facilitating work lives that foster constructive and balanced relationships between professional and private spheres in order to retain employees. Drawing on the conservation of resources theory, we propose that motivational climate influence turnover intention through the facilitation of work–home spillover. Specifically, we argue that employees working in a perceived mastery climate are less likely to consider voluntarily leaving their employer because of increased positive—and reduced negative—work–home spillover experiences. We further argue (...) that employees working in a perceived performance climate are more likely to consider voluntarily leaving their employer because of reduced positive—and increased negative—work–home spillover experiences. In a cross-lagged survey of 1074 employees in a Norwegian financial-sector organization, we found that work–home spillover partly mediates the relationship between a perceived mastery climate and turnover intention. Specifically, mastery climates seem to facilitate positive—and reduce negative—spillover between the professional and private spheres, which in turn decreases employees’ turnover intention. We discuss implications for practice and future research. (shrink)

© 2017 CERN.A measurement of the inclusive pp→tt+X production cross section in the τ+jets final state using only the hadronic decays of the τ lepton is presented. The measurement is performed using 20.2 fb-1 of proton-proton collision data recorded at a center-of-mass energy of s=8 TeV with the ATLAS detector at the Large Hadron Collider. The cross section is measured via a counting experiment by imposing a set of selection criteria on the identification and kinematic variables of the reconstructed particles (...) and jets, and on event kinematic variables and characteristics. The production cross section is measured to be σtt=239±29 pb, which is in agreement with the measurements in other final states and the theoretical predictions at this center-of-mass energy. (shrink)

© 2017, CERN for the benefit of the ATLAS collaboration.A measurement of the calorimeter response to isolated charged hadrons in the ATLAS detector at the LHC is presented. This measurement is performed with 3.2 nb- 1 of proton–proton collision data at s=7 TeV from 2010 and 0.1 nb- 1 of data at s=8 TeV from 2012. A number of aspects of the calorimeter response to isolated hadrons are explored. After accounting for energy deposited by neutral particles, there is a 5% (...) discrepancy in the modelling, using various sets of Geant4 hadronic physics models, of the calorimeter response to isolated charged hadrons in the central calorimeter region. The description of the response to anti-protons at low momenta is found to be improved with respect to previous analyses. The electromagnetic and hadronic calorimeters are also examined separately, and the detector simulation is found to describe the response in the hadronic calorimeter well. The jet energy scale uncertainty and correlations in scale between jets of different momenta and pseudorapidity are derived based on these studies. The uncertainty is 2–5% for jets with transverse momenta above 2 TeV, where this method provides the jet energy scale uncertainty for ATLAS. (shrink)

© 2017, The Author.Differential cross sections are presented for the prompt and non-prompt production of the hidden-charm states X and ψ, in the decay mode J/ψπ+π−, measured using 11.4 fb−1 of pp collisions at s=8 TeV by the ATLAS detector at the LHC. The ratio of cross-sections X/ψ is also given, separately for prompt and non-prompt components, as well as the non-prompt fractions of X and ψ. Assuming independent single effective lifetimes for non-prompt X and ψ production gives RB=ℬ+any)ℬ→J/ψπ+π−)/ℬ+any)ℬ→J/ψπ+π−)=±0.08)×10−2 separating (...) short- and long-lived contributions, assuming that the short-lived component is due to Bc decays, gives RB = ± 0.11) × 10−2, with the fraction of non-prompt X produced via Bc decays for pT) > 10 GeV being ± 2 ± 5)%. The distributions of the dipion invariant mass in the X and ψ decays are also measured and compared to theoretical predictions.[Figure not available: see fulltext.]. (shrink)

© 2017, The Author.Same- and opposite-sign charge asymmetries are measured in lepton+jets tt¯ events in which a b-hadron decays semileptonically to a soft muon, using data corresponding to an integrated luminosity of 20.3 fb−1 from proton-proton collisions at a centre-of-mass energy of s=√8 TeV collected with the ATLAS detector at the Large Hadron Collider at CERN. The charge asymmetries are based on the charge of the lepton from the top-quark decay and the charge of the soft muon from the semileptonic (...) decay of a b-hadron and are measured in a fiducial region corresponding to the experimental acceptance. Four CP asymmetries are measured and are found to be compatible with zero and consistent with the Standard Model.[Figure not available: see fulltext.]. (shrink)

© 2016 The Author.The top quark mass is measured in the tt̄ → dileptonchannel using ATLAS data recorded in the year 2012 at the LHC. The data were taken at a proton-proton centre-of-mass energy of √s=8 TeV and correspond to an integrated luminosity of about 20.2fb-1. Exploiting the template method, and using the distribution of invariant masses of lepton-b-jetpairs, the top quark mass is measured to be mtop=172.99 ±0.41 ±0.74 GeV, with a total uncertainty of 0.84 GeV. Finally, acombination with (...) previous ATLAS mtop measurements from √s=7TeVdata in the tt̄ → dilepton and tt̄→lepton+jetschannels results in mtop=172.84 ±0.34 ±0.61 GeV, with a total uncertainty of 0.70 GeV. (shrink)

© 2016 The Author.This paper describes a measurement of the inclusive top quark pair production cross-section with a data sample of 3.2 fb−1of proton-proton collisions at a centre-of-mass energy of √s=13 TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron-muon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly (...) two b-tagged jets are counted and used to determine simultaneously σtt̄and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be: σtt̄ = 818±8 ± 27 ±19 ± 12 pb, where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented. (shrink)

© 2016 The Author.The production of W±Z events in proton–proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC. The collected data correspond to an integrated luminosity of 3.2 fb−1. The W±Z candidates are reconstructed using leptonic decays of the gauge bosons into electrons or muons. The measured inclusive cross section in the detector fiducial region for leptonic decay modes is σfid.W±Z→ℓʹ νℓℓ=63.2 ±3.2 ±2.6 ±1.5 fb. In comparison, the next-to-leading-order Standard Model (...) prediction is 53.4+3.6−2.8fb. The extrapolation of the measurement from the fiducial to the total phase space yields σtot.W±Z=50.6 ±2.6 ±2.0 ±0.9 ±1.2 pb, in agreement with a recent next-to-next-to-leading-order calculation of 48.2+1.1−1.0pb. The cross section as a function of jet multiplicity is also measured, together with the charge-dependent W+Z and W−Z cross sections and their ratio. (shrink)

© 2016, CERN for the benefit of the ATLAS collaboration.The algorithms used by the ATLAS Collaboration to reconstruct and identify prompt photons are described. Measurements of the photon identification efficiencies are reported, using 4.9 fb- 1 of pp collision data collected at the LHC at s=7 TeV and 20.3 fb- 1 at s=8 TeV. The efficiencies are measured separately for converted and unconverted photons, in four different pseudorapidity regions, for transverse momenta between 10 GeV and 1.5 TeV. The results from (...) the combination of three data-driven techniques are compared to the predictions from a simulation of the detector response, after correcting the electromagnetic shower momenta in the simulation for the average differences observed with respect to data. Data-to-simulation efficiency ratios used as correction factors in physics measurements are determined to account for the small residual efficiency differences. These factors are measured with uncertainties between 0.5% and 10% in 7 TeV data and between 0.5% and 5.6% in 8 TeV data, depending on the photon transverse momentum and pseudorapidity. (shrink)

© 2017, CERN for the benefit of the ATLAS collaboration.A measurement of the tt¯ Z and tt¯ W production cross sections in final states with either two same-charge muons, or three or four leptons is presented. The analysis uses a data sample of proton–proton collisions at s=13 TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015, corresponding to a total integrated luminosity of 3.2 fb- 1. The inclusive cross sections are extracted using likelihood fits to signal (...) and control regions, resulting in σtt¯Z= 0.9 ± 0.3 pb and σtt¯W= 1.5 ± 0.8 pb, in agreement with the Standard Model predictions. (shrink)

© 2017, The Author.A measurement of the ZZ production cross section in the ℓ−ℓ+ℓ′ −ℓ′ + and ℓ−ℓ+νν¯ channels in proton-proton collisions at s=8TeV at the Large Hadron Collider at CERN, using data corresponding to an integrated luminosity of 20.3 fb−1 collected by the ATLAS experiment in 2012 is presented. The fiducial cross sections for ZZ → ℓ−ℓ+ℓ′ −ℓ′ + and ZZ→ ℓ−ℓ+νν¯ are measured in selected phase-space regions. The total cross section for ZZ events produced with both Z bosons (...) in the mass range 66 to 116 GeV is measured from the combination of the two channels to be 7.3 ± 0.4 ± 0.3− 0.1− 0.2 pb, which is consistent with the Standard Model prediction of 6. 6− 0.6+ 0.7 pb. The differential cross sections in bins of various kinematic variables are presented. The differential event yield as a function of the transverse momentum of the leading Z boson is used to set limits on anomalous neutral triple gauge boson couplings in ZZ production.[Figure not available: see fulltext.]. (shrink)

© 2017, CERN for the benefit of the ATLAS collaboration.The production of two prompt J/ ψ mesons, each with transverse momenta pT> 8.5 GeV and rapidity |y| < 2.1, is studied using a sample of proton-proton collisions at s=8 TeV, corresponding to an integrated luminosity of 11.4 fb- 1 collected in 2012 with the ATLAS detector at the LHC. The differential cross-section, assuming unpolarised J/ ψ production, is measured as a function of the transverse momentum of the lower-pTJ/ ψ meson, (...) di-J/ ψpT and mass, the difference in rapidity between the two J/ ψ mesons, and the azimuthal angle between the two J/ ψ mesons. The fraction of prompt pair events due to double parton scattering is determined by studying kinematic correlations between the two J/ ψ mesons. The total and double parton scattering cross-sections are compared with predictions. The effective cross-section of double parton scattering is measured to be σeff= 6.3 ± 1.6 ± 1.0 mb. (shrink)

© 2017, The Author.Ratios of top-quark pair to Z-boson cross sections measured from proton-proton collisions at the LHC centre-of-mass energies of s=13 TeV, 8 TeV, and 7 TeV are presented by the ATLAS Collaboration. Single ratios, at a given s for the two processes and at different s for each process, as well as double ratios of the two processes at different s, are evaluated. The ratios are constructed using previously published ATLAS measurements of the tt¯ and Z-boson production cross (...) sections, corrected to a common phase space where required, and a new analysis of Z → ℓ+ℓ− where ℓ = e, μ at s=13 TeV performed with data collected in 2015 with an integrated luminosity of 3.2 fb−1. Correlations of systematic uncertainties are taken into account when evaluating the uncertainties in the ratios. The correlation model is also used to evaluate the combined cross section of the Z → e+e− and the Z → μ+μ− channels for each s value. The results are compared to calculations performed at next-to-next-to-leading-order accuracy using recent sets of parton distribution functions. The data demonstrate significant power to constrain the gluon distribution function for the Bjorken-x values near 0.1 and the light-quark sea for x < 0.02.[Figure not available: see fulltext.]. (shrink)

© 2017, The Author.Measurements of top quark spin observables in tt¯ events are presented based on 20.2 fb−1 of s=8 TeV proton-proton collisions recorded with the ATLAS detector at the LHC. The analysis is performed in the dilepton final state, characterised by the presence of two isolated leptons. There are 15 observables, each sensitive to a different coefficient of the spin density matrix of tt¯ production, which are measured independently. Ten of these observables are measured for the first time. All (...) of them are corrected for detector resolution and acceptance effects back to the parton and stable-particle levels. The measured values of the observables at parton level are compared to Standard Model predictions at next-to-leading order in QCD. The corrected distributions at stable-particle level are presented and the means of the distributions are compared to Monte Carlo predictions. No significant deviation from the Standard Model is observed for any observable.[Figure not available: see fulltext.]. (shrink)

© 2017, CERN for the benefit of the ATLAS collaboration.This paper presents a measurement of the polarisation of W bosons from tt¯ decays, reconstructed in events with one high-pT lepton and at least four jets. Data from pp collisions at the LHC were collected at s = 8 TeV and correspond to an integrated luminosity of 20.2 fb- 1. The angle θ∗ between the b-quark from the top quark decay and a direct W boson decay product in the W boson (...) rest frame is sensitive to the W boson polarisation. Two different W decay products are used as polarisation analysers: the charged lepton and the down-type quark for the leptonically and hadronically decaying W boson, respectively. The most precise measurement of the W boson polarisation via the distribution of cos θ∗ is obtained using the leptonic analyser and events in which at least two of the jets are tagged as b-quark jets. The fitted fractions of longitudinal, left- and right-handed polarisation states are F0=0.709±0.019, FL=0.299±0.015 and FR=-0.008±0.014, and are the most precisely measured W boson polarisation fractions to date. Limits on anomalous couplings of the Wtb vertex are set. (shrink)

© 2016 The AuthorA measurement of the total pp cross section at the LHC at s=8 TeV is presented. An integrated luminosity of 500 μb−1 was accumulated in a special run with high-β⋆ beam optics to measure the differential elastic cross section as a function of the Mandelstam momentum transfer variable t. The measurement is performed with the ALFA sub-detector of ATLAS. Using a fit to the differential elastic cross section in the −t range from 0.014 GeV2 to 0.1 GeV2 (...) to extrapolate t→0, the total cross section, σtot, is measured via the optical theorem to beσtot=96.07±0.18±0.85±0.31mb, where the first error is statistical, the second accounts for all experimental systematic uncertainties and the last is related to uncertainties in the extrapolation t→0. In addition, the slope of the exponential function describing the elastic cross section at small t is determined to be B=19.74±0.05±0.23GeV−2. (shrink)

© 2016, CERN for the benefit of the ATLAS collaboration.The dijet production cross section for jets containing a b-hadron has been measured in proton–proton collisions with a centre-of-mass energy of s=7 TeV, using the ATLAS detector at the LHC. The data used correspond to an integrated luminosity of 4.2fb-1. The cross section is measured for events with two identified b-jets with a transverse momentum pT> 20 GeV and a minimum separation in the η–ϕ plane of Δ R= 0.4. At least (...) one of the jets in the event is required to have pT> 270 GeV. The cross section is measured differentially as a function of dijet invariant mass, dijet transverse momentum, boost of the dijet system, and the rapidity difference, azimuthal angle and angular distance between the b-jets. The results are compared to different predictions of leading order and next-to-leading order perturbative quantum chromodynamics matrix elements supplemented with models for parton-showers and hadronization. (shrink)

© 2016 The Author.The production of Wboson pairs in association with one jet in pp collisions at √s = 8 TeV is studied using data corresponding to an integrated luminosity of 20.3 fb-1collected by the ATLAS detector during 2012 at the CERN Large Hadron Collider. The cross section is measured in a fiducial phase-space region defined by the presence of exactly one electron and one muon, missing transverse momentum and exactly one jet with a transverse momentum above 25 GeV and (...) a pseudorapidity of |η| <4.5. The leptons are required to have opposite electric charge and to pass transverse momentum and pseudorapidity requirements. The fiducial cross section is found to be σWWfid,1-jet= 136 ± 6 ± 14 ± 3 fb. In combination with a previous measurement restricted to leptonic final states with no associated jets, the fiducial cross section of WW production with zero or one jet is measured to be σWWfid,≤1-jet= 511 ±9 ±26 ±10 fb. The ratio of fiducial cross sections in final states with one and zero jets is determined to be 0.36 ±0.05. Finally, a total cross section extrapolated from the fiducial measurement of WW production with zero or one associated jet is reported. The measurements are compared to theoretical predictions and found in good agreement. (shrink)

© 2016The W boson angular distribution in events with high transverse momentum jets is measured using data collected by the ATLAS experiment from proton–proton collisions at a centre-of-mass energy s=8 TeV at the Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb−1. The focus is on the contributions to W+jets processes from real W emission, which is achieved by studying events where a muon is observed close to a high transverse momentum jet. At small angular separations, these contributions (...) are expected to be large. Various theoretical models of this process are compared to the data in terms of the absolute cross-section and the angular distributions of the muon from the leptonic W decay. (shrink)

© 2016, CERN for the benefit of the ATLAS collaboration.The result of a search for pair production of the supersymmetric partner of the Standard Model bottom quark is reported. The search uses 3.2 fb- 1 of pp collisions at s=13 TeV collected by the ATLAS experiment at the Large Hadron Collider in 2015. Bottom squarks are searched for in events containing large missing transverse momentum and exactly two jets identified as originating from b-quarks. No excess above the expected Standard Model (...) background yield is observed. Exclusion limits at 95 % confidence level on the mass of the bottom squark are derived in phenomenological supersymmetric R-parity-conserving models in which the b~1 is the lightest squark and is assumed to decay exclusively via b~1→bχ~10, where χ~10 is the lightest neutralino. The limits significantly extend previous results; bottom squark masses up to 800 GeV are excluded for the χ~10 mass below 360 GeV whilst differences in mass above 100 GeV between the b~1 and the χ~10 are excluded up to a b~1 mass of 500 GeV. (shrink)

© 2016 The AuthorA search for dark matter pair production in association with a Higgs boson decaying to a pair of bottom quarks is presented, using 3.2 fb−1of pp collisions at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the LHC. The decay of the Higgs boson is reconstructed as a high-momentum bb¯ system with either a pair of small-radius jets, or a single large-radius jet with substructure. The observed data are found to be consistent with (...) the expected backgrounds. Results are interpreted using a simplified model with a Z′gauge boson mediating the interaction between dark matter and the Standard Model as well as a two-Higgs-doublet model containing an additional Z′boson which decays to a Standard Model Higgs boson and a new pseudoscalar Higgs boson, the latter decaying into a pair of dark matter particles. (shrink)