The Electromagnetic Form Factor of the Kaon in the Light-Front Approach

The kaon electromagnetic form factor is calculated within a light-front constituent quark model (LFCQM). The electromagnetic components of the current are extracted from the Feynman triangle diagram within the light-front approach. We also obtain the electroweak decay constant and the charge radius for the kaon in the light-front approach. In this work, the kaon observables are calculated and a fairly good agreement is obtained with a very higher accuracy when compared with the experimental data.Comment: Paper with 4 pages, 1 figure, reference: XII HADRON PHYSICS Conference - to appear in AIP Conference Proceeding

Electromagnetic Structure of the Pion

In this work, we analyze the electromagnetic structure of the pion. We calculate its electromagnetic radius and electromagnetic form factor in low and intermediate momentum range. Such observables are determined by means of a theoretical model that takes into account the constituent quark and antiquark of the pion within the formalism of light-front field theory. In particular, we consider a nonsymmetrical vertex in this model, with which we calculate the electromagnetic form factor of the pion in an optimized way, so that we obtain a value closer to the experimental charge radius of the pion. The theoretical calculations are also compared with the most recent experimental data involving the pion electromagnetic form factor and the results show very good agreement.Comment: Paper with 4 pages, 1 figure, presented in XII HADRON PHYSICS Conference - to appear in AIP Conference Proceeding

Pion and kaon elastic form factors in a refined light-front model

Within the framework of light-front field theory, we reassess the electromagnetic form factors of the pion and kaon. Comparison with experiment is made for the full range of momentum transfer, q^2<0, including recent data. The light-front model's single regulator mass, m_R, of the \bar qq bound-state vertex function is initially adjusted to reproduce the weak decay constants, f_\pi\ and f_K, and both meson's charge radii, r_\pi\ and r_K. We study the behavior of these observables under variation of the quark masses and find an optimized parameter set, m_u=m_d, m_s and m_R, for which they are in sensibly better agreement with experiment than in a previous analysis; a feature also observed for the elastic form factors, in particular at small q^2. This model refinement is important in view of an extension to vector and heavy-light mesons.Comment: 5 pages, 8 figures; minor corrections, version published in PRC C86, 038202 (2012

Scaling properties of the Fermi-Ulam model

The chaotic low energy region (chaotic sea) of the Fermi-Ulam accelerator model is discussed within a scaling framework near the integrable to non-integrable transition. Scaling results for the average quantities (velocity, roughness, energy etc.) of the simplified version of the model are reviewed and it is shown that, for small oscillation amplitude of the moving wall, they can be described by scaling functions with the same characteristic exponents. New numerical results for the complete model are presented. The chaotic sea is also characterized by its Lyapunov exponents

Anomalous oriented attachment growth behavior on SnO2 nanocrystals

This work reports a detailed characterization of an anomalous oriented attachment behaviour for SnO2 nanocrystals. Our results evidenced an anisotropic growth for two identical 〈110〉 directions, which are equivalent according to the SnO2 crystallographic structure symmetry. A hypothesis is proposed to describe this behaviour

5-(3-Nitro­benz­yl)-1,3,4-thia­diazol-2-amine

In the title mol­ecule, C9H8N4O2S, the dihedral angle between the thia­diazole and benzene rings is 73.92 (8)° and the thia­diazole group S atom is orientated towards the benzene ring, the central S—C—C—C torsion angle being 45.44 (18)°. In the crystal, supra­molecular tapes mediated by N—H⋯N hydrogen bonds and comprising alternating eight-membered {⋯HNCN}2 and 10-membered {⋯HNH⋯NN}2 synthons are formed along [010]. The tapes are consolidated into a three-dimensional network by a combination of C—H⋯O, C—H⋯S and C—H⋯π inter­action

ANÃLISE DE MODELOS FUNCIONAIS EM PAISAGENS LITORÂNEAS

O objetivo principal é analisar o funcionamento e dinâmica do conjunto paisagístico da APA do Estuário do Rio Curu e seu entorno em relação aos fatores de influências naturais e antropogênicas. Para tanto, foi aplicada as concepções da Geoecologia das Paisagens, numa área entre os municípios de Paraipaba e Paracuru, litoral oeste do Estado do Ceará, com vista a esclarecer de que forma a paisagem está estruturada e quais as relações funcionais entre seus elementos. O modelo funcional evidencia as conexões da paisagem de níveis hierárquicos diferentes que se unem mediante a ação das relações laterais. Essa ação, confere a integraçãofuncional e o intercâmbio de energias e matéria que se produzem entre os diversos sistemas que compõem a paisagem estudada. Sobre a base de análise pode-se desenvolver ideias e recomendações para o uso sustentável de acordo com os princípios geoecológicos eficaz para as áreas litorâneas.AbstractThe main objective is to analyze the functioning and dynamics of landscape set of APA from Estuary of Curu River and its surroundings in relation to natural and anthropogenic influences factors. For both , the conceptions of Geoecology of Landscapes was applied in an area between the towns of Paraipaba and Paracuru, west coast of the state of Ceará, in order to clarify how the landscape is structured and what are the functional relationships between its elements. The functional model shows the connections of the landscape at different hierarchical levels who come together through the action of relations side. This action gives the functional integration and the exchange of energy and matter that are produced between the various systems that compose the landscape studied. About the basis of analysis can develop ideas and  recommendations for sustainable use in accordance with the geoecological principles effective for coastal areas

Inibição do catabolismo de citrato in vitro pelos ácidos DL-2-hidroxibutírico e 4-hidroxibutírico em córtex cerebral de ratos jovens

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