2,968 research outputs found

    Charm-quark mass from weighted finite energy QCD sum rules

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    The running charm-quark mass in the MSˉ\bar{MS} scheme is determined from weighted finite energy QCD sum rules (FESR) involving the vector current correlator. Only the short distance expansion of this correlator is used, together with integration kernels (weights) involving positive powers of ss, the squared energy. The optimal kernels are found to be a simple {\it pinched} kernel, and polynomials of the Legendre type. The former kernel reduces potential duality violations near the real axis in the complex s-plane, and the latter allows to extend the analysis to energy regions beyond the end point of the data. These kernels, together with the high energy expansion of the correlator, weigh the experimental and theoretical information differently from e.g. inverse moments FESR. Current, state of the art results for the vector correlator up to four-loop order in perturbative QCD are used in the FESR, together with the latest experimental data. The integration in the complex s-plane is performed using three different methods, fixed order perturbation theory (FOPT), contour improved perturbation theory (CIPT), and a fixed renormalization scale μ\mu (FMUPT). The final result is mˉc(3 GeV)=1008 ± 26 MeV\bar{m}_c (3\, {GeV}) = 1008\,\pm\, 26\, {MeV}, in a wide region of stability against changes in the integration radius s0s_0 in the complex s-plane.Comment: A short discussion on convergence issues has been added at the end of the pape

    Study of moments of event shapes in e+e- annihilation using JADE data

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    Data from e+e- annihilation into hadrons collected by the JADE experiment at centre-of-mass energies between 14 GeV and 44 GeV were used to study moments of event shape distributions. The data were compared with Monte Carlo models and with predictions from QCD NLO order calculations. The strong coupling constant measured from the moments is alpha_S(M_Z) = 0.1286 +/- 0.0007 (stat) +/- 0.0011 (expt) +/- 0.0022 (had) +/- 0.0068 (theo), alpha_S(M_Z) = 0.1286 +/- 0.0072 (total error), consistent with the world average. However, systematic deficiencies in the QCD NLO order predictions are visible for some of the higher moments.Comment: JADE note 147 submitted as contributed paper to ICHEP 2004, corrected statistical error of 6 observable average and several typo

    Measurement of the Strong Coupling Constant alpha_S from the Four-Jet Rate in e+e- Annihilation using JADE data

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    Data from e+e- annihilation into hadrons collected by the JADE experiment at centre-of-mass energies between 14 GeV and 44 GeV were used to study the four-jet rate as a function of the Durham algorithm's resolution parameter y_cut. The four-jet rate was compared to a QCD NLO order calculations including NLLA resummation of large logarithms. The strong coupling constant measured from the four-jet rate is alpha_S(M_Z) = 0.1169 +/- 0.0004 (stat) +/- 0.0012 (expt) +/- 0.0021 (had) +/- 0.0007 (theo), alpha_S(M_Z) = 0.1169 +/- 0.0026 (total error) in agreement with the world average.Comment: JADE note 146 submitted as contributed paper to ICHEP 200

    Jobs and Productivity Growth in Global Value Chains:New Evidence for Twenty-five Low- and Middle-Income Countries

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    Using newly developed data, the evolution of job and productivity growth in global value chains (GVCs) is analyzed for 25 low- and middle-income countries. GVC jobs are found to be more productive than non-GVC jobs. Their share in the total labor force is small, in particular for low-income countries. Growth in GVC jobs varies widely across countries in the period 2000–2014. Part of this can be accounted for by differences in the type of consumer market served. A bigger part is accounted for by the speed with which countries expand activities within supply chains, measured by their shares in GVC value added. Expansion in GVCs is positively correlated with labor productivity across countries as well as over time within GVC

    A preliminary investigation of the potential for thermographic images to influence householders' understanding of home energy consumption

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    This paper explores the potential connections between the thermographic (infrared) imaging of domestic properties and the impact (on energy conservation behaviours) of showing householders infrared images of their homes. Infrared (IR) images, or thermographic imaging, as it has become known has been applied to the investigation of heat losses and other building related phenomena such as moisture penetration of roofs and failures in damp-proofing systems for a number of years. Recently it has been used by a wide range of public and private bodies to demonstrate the heat of a home in a visible format. This suggests a connection between the householder viewing an IR image and engaging in energy conservation behaviour, such as installing insulation. It is hypothesised that information presented in a manner which attracts the attention of the intended audience, being vivid, specific and personal, is more likely to achieve behaviour change (Stern, 1992). In this paper the evidence of the thermal characteristic of the dwelling (as shown within the thermographic image) will be compared with the householder’s reasoning process as prompted by viewing the images. The possible increase in energy saving behaviours and changes in related attitudes leading from this intervention will be investigated. Questions concerning the links between the householder’s reactions to the images and the possibility that this may facilitate a reduction in energy consumption will be discussed

    Managing change toward adaptive water management through social learning

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    The management of water resources is currently undergoing a paradigm shift toward a more integrated and participatory management style. This paper highlights the need to fully take into account the complexity of the systems to be managed and to give more attention to uncertainties. Achieving this requires adaptive management approaches that can more generally be defined as systematic strategies for improving management policies and practices by learning from the outcomes of previous management actions. This paper describes how the principles of adaptive water management might improve the conceptual and methodological base for sustainable and integrated water management in an uncertain and complex world. Critical debate is structured around four questions: (1) What types of uncertainty need to be taken into account in water management? (2) How does adaptive management account for uncertainty? (3) What are the characteristics of adaptive management regimes? (4) What is the role of social learning in managing change? Major transformation processes are needed because, in many cases, the structural requirements, e.g., adaptive institutions and a flexible technical infrastructure, for adaptive management are not available. In conclusion, we itemize a number of research needs and summarize practical recommendations based on the current state of knowledge

    eViz - Energy Visualisation for Carbon Reduction

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    Cross-Comparison of Climate Change adaptation Strategies Across Large River Basins in Europe, Africa and Asia

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    A cross-comparison of climate change adaptation strategies across regions was performed, considering six large river basins as case study areas. Three of the basins, namely the Elbe, Guadiana, and Rhine, are located in Europe, the Nile Equatorial Lakes region and the Orange basin are in Africa, and the Amudarya basin is in Central Asia. The evaluation was based mainly on the opinions of policy makers and water management experts in the river basins. The adaptation strategies were evaluated considering the following issues: expected climate change, expected climate change impacts, drivers for development of adaptation strategy, barriers for adaptation, state of the implementation of a range of water management measures, and status of adaptation strategy implementation. The analysis of responses and cross-comparison were performed with rating the responses where possible. According to the expert opinions, there is an understanding in all six regions that climate change is happening. Different climate change impacts are expected in the basins, whereas decreasing annual water availability, and increasing frequency and intensity of droughts (and to a lesser extent floods) are expected in all of them. According to the responses, the two most important drivers for development of adaptation strategy are: climate-related disasters, and national and international policies. The following most important barriers for adaptation to climate change were identified by responders: spatial and temporal uncertainties in climate projections, lack of adequate financial resources, and lack of horizontal cooperation. The evaluated water resources management measures are on a relatively high level in the Elbe and Rhine basins, followed by the Orange and Guadiana. It is lower in the Amudarya basin, and the lowest in the NEL region, where many measures are only at the planning stage. Regarding the level of adaptation strategy implementation, it can be concluded that the adaptation to climate change has started in all basins, but progresses rather slowl
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