Spin-1 Particles with Light-Front Approach

For the vector sector, i.e, mesons with spin-1, the electromagnetic form factors and anothers observables are calculated with the light-front approach. However, the light-front quantum field theory have some problems, for example, the rotational symmetry breaking. We solve that problem added the zero modes contribuition to the matrix elements of the electromagnetic current, besides the valence contribuition. We found that among the four independent matrix elements of the plus component in the light-front helicity basis only the $0\to 0$ one carries zero mode contributions.Comment: 5 pages. 3 Figures, use latex and EPJ styl

Vacuum Polarization for a Massless Spin-1/2 Field in the Global Monopole Spacetime at Nonzero Temperature

In this paper we present the effects produced by the temperature in the renormalized vacuum expectation value of the zero-zero component of the energy-momentum tensor associated with massless left-handed spinor field in the pointlike global monopole spacetime. In order to develop this calculation we had to obtain the Euclidean thermal Green function in this background. Because the expression obtained for the thermal energy density cannot be expressed in a closed form, its explicit dependence on the temperature is not completely evident. So, in order to obtain concrete information about its thermal behavior, we develop a numerical analysis of our result in the high-temperature limit for specific values of the parameter $\alpha$ which codify the presence of the monopole.Comment: 22 pages, LaTex format, 5 figure

Medidas comparativas de eficiências aeroportuárias.

São encontradas na literatura algumas formas de medida de eficiência aeroportuária. É aqui apresentada uma nova abordagem baseada em Análise de Envoltório de Dados, que utiliza programação linear para calcular uma medida de eficiência comparada. São utilizados os dados encontrados na literatura e o estudo é dividido em dois conjuntos de avaliação: aeroportos brasileiros e aeroportos brasileiros em conjunto com aeroportos estrangeiros. Em ambos os casos, calculam-se as eficiências operacional, comercial (que considera as receitas não aeroportuárias) e global

Olympic ranking based on a zero sum gains DEA model.

It is usual to rank the participant countries in the Olympic Games in accordance with the number of medals they have won. An alternative ranking is suggested in this paper. This ranking is based on each country's ability to win medals in relation to its available resources. This is an efficiency that can be measured with the help of data envelopment analysis (DEA) for which two models exist: the traditional DEA model, that takes into account variable returns to scale, and a DEA model based on the premise that the sum of the gains is zero (constant sum of outputs). It is the latter that is developed in this paper

Análise de envoltória de dados para avaliação de eficiência e caracterização de tipologias em agricultura: um estudo de caso.

Este artigo usa Análise de Envoltória de Dados (DEA) para medir a eficiência de uma amostra de agricultores de Holambra, município do Estado de São Paulo

Verification of Magnitude and Phase Responses in Fixed-Point Digital Filters

In the digital signal processing (DSP) area, one of the most important tasks is digital filter design. Currently, this procedure is performed with the aid of computational tools, which generally assume filter coefficients represented with floating-point arithmetic. Nonetheless, during the implementation phase, which is often done in digital signal processors or field programmable gate arrays, the representation of the obtained coefficients can be carried out through integer or fixed-point arithmetic, which often results in unexpected behavior or even unstable filters. The present work addresses this issue and proposes a verification methodology based on the digital-system verifier (DSVerifier), with the goal of checking fixed-point digital filters w.r.t. implementation aspects. In particular, DSVerifier checks whether the number of bits used in coefficient representation will result in a filter with the same features specified during the design phase. Experimental results show that errors regarding frequency response and overflow are likely to be identified with the proposed methodology, which thus improves overall system's reliability

Nonplanar integrability at two loops

In this article we compute the action of the two loop dilatation operator on restricted Schur polynomials that belong to the su(2) sector, in the displaced corners approximation. In this non-planar large N limit, operators that diagonalize the one loop dilatation operator are not corrected at two loops. The resulting spectrum of anomalous dimensions is related to a set of decoupled harmonic oscillators, indicating integrability in this sector of the theory at two loops. The anomalous dimensions are a non-trivial function of the 't Hooft coupling, with a spectrum that is continuous and starting at zero at large N, but discrete at finite N.Comment: version to appear in JHE