Why Pair Production Cures Covariance in the Light-Front?

We show that the light-front vacuum is not trivial, and the Fock space for positive energy quanta solutions is not complete. As an example of this non triviality we have calculated the electromagnetic current for scalar bosons in the background field method were the covariance is restored through considering the complete Fock space of solutions.In this work we construct the electromagnetic current operator for a system composed of two free bosons. The technique employed to deduce these operators is through the definition of global propagators in the light front when a background electromagnetic field acts on one of the particles.

Search for the Associated Production of a b Quark and a Neutral Supersymmetric Higgs Boson that Decays into tau Pairs

We report results from a search for production of a neutral Higgs boson in association with a b quark. We search for Higgs decays to tau pairs with one tau subsequently decaying to a muon and the other to hadrons. The data correspond to 2: 7 fb(-1) of p (p) over bar collisions recorded by the D0 detector at.. root s = 1.96 TeV. The data are found to be consistent with background predictions. The result allows us to exclude a significant region of parameter space of the minimal supersymmetric model.

Measurement of the production cross section for pairs of isolated photons in pp collisions at root s=7 TeV

The integrated and differential cross sections for the production of pairs of isolated photons is measured in proton-proton collisions at a centre-of-mass energy of 7TeV with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 36 pb(-1) is analysed. A next-to-leading-order perturbative QCD calculation is compared to the measurements. A discrepancy is observed for regions of the phase space where the two photons have an azimuthal angle difference Delta phi less than or similar to 2.8 rad.

Competition between suppression and production of Fermi acceleration

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Espaço geográfico, produção e movimento: uma reflexão sobre o conceito de circuito espacial produtivo

O propósito deste artigo é demonstrar a importância e a operacionalidade dos conceitos de circuito espacial produtivo e círculos de cooperação no espaço, num momento histórico em que as esferas da produção e da troca tornam-se geograficamente mais dispersas, fazendo da circulação uma prioridade e um campo de atuação estratégica de Estados e empresas. Procura-se alcançar esse objetivo em três passos: 1) elaboração de uma discussão teórica com base nos autores que propuseram e procuraram desenvolver os conceitos; 2) proposição de uma distinção entre circuito espacial produtivo e cadeia produtiva; 3) uma breve análise da produção agrícola moderna em áreas de fronteira agrícola no território brasileiro à luz dessa teoria.

R-parity-violating signals for chargino production at LEP II

We study chargino pair production at LEP II in supersymmetric models with spontaneously broken R-parity. We perform signal and background analyses, showing that a large region of the parameter space of these models can be probed through chargino searches at LEP II. In particular, we determine the attainable limits on the chargino mass as a function of the magnitude of the effective bilinear R-parity violation parameter ∈, demonstrating that LEP II is able to unravel the existence of charginos with masses almost up to their kinematical limit even in the case of R-parity violation. This requires the study of several final state topologies since the usual MSSM chargino signature is recovered as ∈ → 0. Moreover, for sufficiently large ∈ values, for which the chargino decay mode χ ± → τ ± J dominates, we find through a dedicated Monte Carlo analysis that the χ ± mass bounds are again very close to the kinematic limit. Our results establish the robustness of the chargino mass limit, in the sense that it is basically model-independent. They also show that LEP II can establish the existence of spontaneous R-parity violation in a large region of parameter space should charginos be produced. © 1999 Elsevier Science B.V.

Probing neutrino mass with multilepton production at the Tevatron in the simplest R-parity violation model

We analyse the production of multileptons in the simplest supergravity model with bilinear violation of R parity at the Fermilab Tevatron. Despite the small .R-parity violating couplings needed to generate the neutrino masses indicated by current atmospheric neutrino data, the lightest supersymmetric particle is unstable and can decay inside the detector. This leads to a phenomenology quite distinct from that of the R-parity conserving scenario. We quantify by how much the supersymmetric multilepton signals differ from the R-parity conserving expectations, displaying our results in the m0 ⊙ m1/2 plane. We show that the presence of bilinear R-parity violating interactions enhances the supersymmetric multilepton signals over most of the parameter space, specially at moderate and large m0. © SISSA/ISAS 2003.

Using state-space techniques to represent frequency dependent single-phase lines directly in time domain

This paper proposes to use a state-space technique to represent a frequency dependent line for simulating electromagnetic transients directly in time domain. The distributed nature of the line is represented by a multiple 1t section network made up of the lumped parameters and the frequency dependence of the per unit longitudinal parameters is matched by using a rational function. The rational function is represented by its equivalent circuit with passive elements. This passive circuit is then inserted in each 1t circuit of the cascade that represents the line. Because the system is very sparse, it is possible to use a sparsity technique to store only nonzero elements of this matrix for saving space and running time. The model was used to simulate the energization process of a 10 km length single-phase line. ©2008 IEEE.

Effect of plastic film mulch on the production of butterhead lettuce cultivars under protected cultivation

The study was performed in a greenhouse with the aim of evaluating the production of butterhead lettuce cultivars with and without plastic film mulch in the summer. The cultivars studied were 'Elisa', 'Lídia', 'Herman' and 'Luísa'. The experimental design was a split plot, in which the main plot was plastic film mulch (with or without black polyethylene film) and the subplots were the cultivars, with three repetitions. The seedlings were grown in Styrofoam trays of 288 cells and transplanted 25 days after seeding in a space of 25 × 25 cm. Harvests were carried out 45 days after transplanting and the following variables were determined: fresh and dry weights of the aerial part, number of leaves per plant, plant height and the longitudinal and transverse diameters of the plant. Significant differences were found only among the cultivars for the characteristics studied, with no cover × cultivar interaction. Fresh weight of the aerial part of 'Lídia' (270.9 g) was greater than that of 'Herman' (142.5 g), but did not differ from those of 'Luísa' (229.8 g) or 'Elisa' (204.8). The dry weight of the aerial part of 'Lídia' (12.4 g) differed statistically only with respect to that of 'Herman' (7.9 g). The cultivars 'Luísa' and 'Elisa' had an aerial part dry weight of 11.4 and 11.2 g, respectively. The number of leaves per plant of the cultivars 'Luísa' (45.1) and 'Elisa' (43.0) was higher than for 'Herman' (24.05), but did not differ from that of the cultivar 'Lídia' (39.5). The mean transverse and longitudinal diameters, as well as the mean height of the plants, showed that 'Lídia', 'Elisa' and 'Luísa' had the greatest values. The cultivars 'Lídia', 'Elisa' and 'Luísa' were the most productive and plastic film mulch had no effect on lettuce production under protected cultivation.

Population, social equity and changing production patterns

Includes bibliography

Redes e verticalidades como estratégias de uso do território por grandes empresas: o exemplo da EMBRAER S/A

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A produção social do espaço urbano em Londrina - PR: a valorização imobiliária e a reestruturação urbana

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fiscal Panorama of Latin America and the Caribbean 2015: Policy space and dilemmas. Executive Summary

The present document provides an up-to-date overview of public debt and fiscal space in the region. The main conclusions show that public debt levels are low in Latin America and high in the Caribbean. Overall, the region has enough fiscal space to apply countercyclical policies and boost production development and the fiscal management of non-renewable natural resources needs to be modernized. It explains that fiscal policy has a very limited impact on the distribution of disposable income and in a volatile macroeconomic environment, reforms should aim to strengthen personal income tax.

International technological dynamics in production sectors: An empirical analysis

A new methodology is proposed for evaluating the economic development opportunities associated with the different industries making up a country’s economic structure. To this end, neo-Schumpeterian concepts are used to reinterpret the tools afforded by the “product space” literature in an attempt to assess the technological pervasiveness and sophistication of different production sectors. The ultimate objective is to develop a description of today’s techno-productive paradigm and the differential role that the various sectors play in it. An analysis of export data from 113 countries and territories for 2005-2009 indicates that the key sectors in the world economy are: industrial machinery, scientific and medical instruments, and pharmaceuticals. The strong performance of sectors based on mature technologies suggests that key sectors originating in different stages in history can survive and overlap one another, much like geological strata, owing to the persistence of older technological systems.

A gênese do arquivo fotográfico de Sebastião Leme: uma leitura da acumulação

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)