Search results for " rule"
showing 10 items of 628 documents
Electromagnetic mass difference of pions at low temperature
1999
We compute low temperature corrections to the electromagnetic mass difference of pions in the chiral limit. The computation is done in a model independent way in the framework of chiral perturbation theory, using the background field method and the hard thermal loop approximation. We also generalize at low temperature the sum rule of Das et al. We find that the mass difference between the charged and neutral pions decreases at low temperature $T$ with respect to the T=0 value. This is so in spite of the fact that charged particles always get a thermal correction to their masses of order $\sim eT$, where $e$ is the gauge coupling constant. Our result can be understood as a consequence of the…
Radiative muon capture and the value of gP in nuclei
1990
Abstract Radiative muon capture by nuclei is analyzed by means of sum rule techniques, providing a total photon yield calculated with RPA precision. The measured yields relative to the ordinary muon capture rate are well reproduced for the nuclei 12C, 16O and 40Ca using a value of the pseudoscalar weak coupling constant gP enhanced by only 25% with respect to its canonical value. Therefore, the large renormalization of gP claimed up to now must be reconsidered.
Pentaquark decay width in QCD sum rules
2005
In a diquark-diquark-antiquark picture of the pentaquark we study the decay $\Theta \rightarrow K^{+} n$ within the framework of QCD sum rules. After evaluation of the relevant three-point function, we extract the coupling $g_{\Theta nK}$ which is directly related to the pentaquark width. Restricting the decay diagrams to those with color exchange between the meson-like and baryon-like clusters reduces the coupling constant by a factor of four. Whereas a small decay width might be possible for a positive parity pentaquark, it seems difficult to explain the measured width for a pentaquark with negative parity.
Nine Rules of Engagement: Reflections on Reflexivity
2019
Wishing to be reflexive, to critically examine our assumptions, is easy. Doing it is less so. For researchers doing a study in their own professional field, it represents a particular challenge. In this essay, I explore this challenge using my own study as exemplar. I am researching workplace inclusion of workers with intellectual disability. As a professional, I have worked with and for people with intellectual disability for many years. The knowledge I bring to my inquiry – about the inabilities, vulnerabilities and needs ascribed to persons labelled thus – is deeply entrenched in common culture, as well as in my professional training. How can I handle this knowledge in my research? To wh…
The foundations of decision theory: An intuitive, operational approach with mathematical extensions
1985
A new axiomatic basis for the foundations of decision theory is introduced and its mathematical development outlined. The system combines direct intuitive operational appeal with considerable structural flexibility in the resulting mathematical framework.
Business Constraints Integration in a Search Engine Optimization Fuzzy Decision Support System
2017
The Internet has dramatically changed the way companies can reach their clients. Henceforth, to develop their business online, companies have to drive qualified traffic to their website. For this, their website must be visible in the first pages of search engine results. Search Engine Optimization (SEO) permits the improvement of the position of a website on the search engines results pages. However, the practice of SEO is complex, and results are uncertain, because search engines do not communicate much about their ranking methods. Moreover, this activity takes time, and requires the implementation of modifications that can alter the visual appearance of the webpages. This paper proposes a…
Rough Set Theory for Supporting Decision Making on Relevance in Browsing Multilingual Digital Resources
2017
Browsing digital library (DL) collections seems to pose a challenge for a user owning to the number of factors like for instance, operability of the system, interface readability or clarity, and retrieval efficiency directly related to it, or the number of digital items within the user’s domain. However, when it comes to searching for an item in a foreign language to the user, the number of the factors arises even more which translates proportionally to the growing number of clicks aimed to retrieve the target item. Such a procedure usually leads to disheartening the user from browsing the digital collections. Our study into the user’s behavior interacting with multilingual DL system is set…
Density gradient expansion of correlation functions
2013
We present a general scheme based on nonlinear response theory to calculate the expansion of correlation functions such as the pair-correlation function or the exchange-correlation hole of an inhomogeneous many-particle system in terms of density derivatives of arbitrary order. We further derive a consistency condition that is necessary for the existence of the gradient expansion. This condition is used to carry out an infinite summation of terms involving response functions up to infinite order from which it follows that the coefficient functions of the gradient expansion can be expressed in terms the local density profile rather than the background density around which the expansion is ca…
Los derechos fundamentales como normas jurídicas materiales en la teoría de Robert Alexy
2011
RESUMEN. La teoría de los derechos fundamentales de Robert Alexy se fundamenta en un concepto material de norma jurídica que es de carácter doble. Por un lado, se define por los rasgos propios de los principios, en consonancia con la idea de argumentación correcta. Pero, por otro lado, sigue teniendo peso la validez jurídica de las normas que contienen derechos fundamentales, consideradas como reglas constitucionales. Tal y como se argumenta en el trabajo, esta ambigüedad de la teoría de la norma de Alexy permite distintos acercamientos, positivistas y no positivistas, que es signo de su riqueza teórica. ABSTRACT. The theory of the civil rights of Robert Alexy is based on a material concept…
Taller de significados inéditos. Redefinición de conceptos siguiendo reglas lógicas
2017
Resumen: El Taller de significados ineditos esta concebido como una practica filosofica para generar nuevos significados mediante la redefinicion, siguiendo reglas logicas, de conceptos del lenguaje ordinario. A partir de unas simples reglas y de un vocabulario seleccionado, los alumnos son capaces de pensar el lenguaje y recrear la realidad, alumbrando significados originales como expresion de su creatividad e imaginacion. Junto a la mejora de la capacidad de definir —una de las operaciones basicas para articular el pensamiento—, el taller tambien puede servir para aprender a vincular conceptos e imagenes y para ejercitar el sentido critico, asi como para hacer uso del diccionario y las TI…