8,217 research outputs found

    Model Independent Results for Heavy Quarkonium

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    We review a number of results for the spectrum and inclusive decays of heavy quarkonium systems which can be derived from QCD under well controlled approximations. They essentially follow from the hierarchy of scales in these systems, which can be efficiently exploited using non-relativistic effective field theories. In particular, we discuss under which conditions non-relativistic potential models emerge as effective theories of QCD.Comment: 15 pages. Invited brief revie

    The renormalization group for correlated scales: one-stage versus two-stage running

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    Nonrelativistic bound states have two low energy scales, a soft scale mu_S of order mv and an ultrasoft scale mu_U of order mv^2. In two-stage running, the soft and ultrasoft scales are lowered from m to mv, and then the ultrasoft scale is lowered from mv to mv^2. In one-stage running, the two scales are lowered in a correlated way using a subtraction velocity. We compare these two methods of summing logarithms and show that only the correlated running in velocity space of the one-stage method correctly reproduces the logarithms in non-relativistic bound states in QED. The argument for one-stage running is general, and should apply to any system with correlated scales.Comment: 9 pages, typos fixed, results and conclusions unchange

    Actualizing Communities of Practice (COPs) and Situated Learning for a Sustainable Eco-Village

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    An eco-village as defined by Robert Gilman is a “human-scale, full-featured settlement where you feel you know the others, and human activities are integrated with natural, biological systems.” Roland Mayerl argued that this maybe ideal, but there are huge challenges. He claims the challenges are at different levels—there is the physical layer that constitutes food production, animals, water and wastewater treatment. Other layers will be the built environment, the economic system and the governance in the village.This paper argues that one of the challenging layers is the human layer that was excluded in the modeling of many eco-village works. While there are many good models of an eco-village, sustainability will primarily be laid on the shoulders of the members of the community or the village for that matter. Sustainability should be espoused by the members of the eco-village. But how can sustainability be attained? What sustainability approach or strategy can be employed?“Communities of practice (COP) are formed by people who engage in a process of collective learning in a shared domain of human endeavor.“ (Wenger, 2004) COPs are concepts commonly applied in organizations and virtual communities. Using this approach together with periphery participation and situated learning, this paper presents a human-based model of a sustainable eco-village and some useful examples.The paper also argues that an eco-village necessitates the support of technology in enhancing and preserving the shared practices. Hence, use of social media deployed in the web is one of the recommended ways that also permit collective action among members of the eco-village

    Effective field theories for heavy quarkonium

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    We review recent theoretical developments in heavy quarkonium physics from the point of view of Effective Field Theories of QCD. We discuss Non-Relativistic QCD and concentrate on potential Non-Relativistic QCD. Our main goal will be to derive QCD Schr\"odinger-like equations that govern the heavy quarkonium physics in the weak and strong coupling regime. We also discuss a selected set of applications, which include spectroscopy, inclusive decays and electromagnetic threshold production.Comment: 162 pages, 30 figures, revised version, references added. Accepted for publication in Reviews of Modern Physic

    O'CIAO an object oriented programming model using CIAO Prolog

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    There have been several previous proposals for the integration of Object Oriented Programming features into Logic Programming, resulting in much support theory and several language proposals. However, none of these proposals seem to have made it into the mainstream. Perhaps one of the reasons for these is that the resulting languages depart too much from the standard logic programming languages to entice the average Prolog programmer. Another reason may be that most of what can be done with object-oriented programming can already be done in Prolog through the meta- and higher-order programming facilities that the language includes, albeit sometimes in a more cumbersome way. In light of this, in this paper we propose an alternative solution which is driven by two main objectives. The first one is to include only those characteristics of object-oriented programming which are cumbersome to implement in standard Prolog systems. The second one is to do this in such a way that there is minimum impact on the syntax and complexity of the language, i.e., to introduce the minimum number of new constructs, declarations, and concepts to be learned. Finally, we would like the implementation to be as straightforward as possible, ideally based on simple source to source expansions

    Brain–computer interface game applications for combined neurofeedback and biofeedback treatment for children on the autism spectrum

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    Individuals with Autism Spectrum Disorder (ASD) show deficits in social and communicative skills, including imitation, empathy, and shared attention, as well as restricted interests and repetitive patterns of behaviors. Evidence for and against the idea that dysfunctions in the mirror neuron system are involved in imitation and could be one underlying cause for ASD is discussed in this review. Neurofeedback interventions have reduced symptoms in children with ASD by self-regulation of brain rhythms. However, cortical deficiencies are not the only cause of these symptoms. Peripheral physiological activity, such as the heart rate, is closely linked to neurophysiological signals and associated with social engagement. Therefore, a combined approach targeting the interplay between brain, body and behavior could be more effective. Brain-computer interface applications for combined neurofeedback and biofeedback treatment for children with ASD are currently nonexistent. To facilitate their use, we have designed an innovative game that includes social interactions and provides neural- and body-based feedback that corresponds directly to the underlying significance of the trained signals as well as to the behavior that is reinforced

    Fermionic contributions to the three-loop static potential

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    We consider the three-loop corrections to the static potential which are induced by a closed fermion loop. For the reduction of the occurring integrals a combination of the Gr\"obner and Laporta algorithm has been used and the evaluation of the master integrals has been performed with the help of the Mellin-Barnes technique. The fermionic three-loop corrections amount to 2% of the tree-level result for top quarks, 8% for bottom quarks and 27% for the charm quark system.Comment: 12 pages, 3 figures, to appear in Phys. Lett.

    Leading Chiral Logarithms to the Hyperfine Splitting of the Hydrogen and Muonic Hydrogen

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    We study the hydrogen and muonic hydrogen within an effective field theory framework. We perform the matching between heavy baryon effective theory coupled to photons and leptons and the relevant effective field theory at atomic scales. This matching can be performed in a perturbative expansion in alpha, 1/m_p and the chiral counting. We then compute the O(m_{l_i}^3 alpha^5/m_p^2 x logarithms) contribution (including the leading chiral logarithms) to the Hyperfine splitting and compare with experiment. They can explain about 2/3 of the difference between experiment and the pure QED prediction when setting the renormalization scale at the rho mass. We give an estimate of the matching coefficient of the spin-dependent proton-lepton operator in heavy baryon effective theory.Comment: 17 pages, LaTeX, minor changes, one reference adde
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