N=2\mathcal{N}=2 Supersymmetry with Central Charge: A Twofold Implementation

In this work, we analyze an extended $\mathcal{N}=2$ supersymmetry with central charge and develop its superspace formulation under two distinct viewpoints. Initially, in the context of classical mechanics, we discuss the introduction of deformed supersymmetric derivatives and their consequence on the deformation of one-dimensional non-linear sigma model. After that, considering a field-theoretical framework, we present an implementation of this superalgebra in two dimensions, such that one of the coordinates is related to the central charge. As an application, in this two-dimensional scenario, we consider topological (bosonic) configurations of a special self-coupled matter model and present a non-trivial fermionic solution.Comment: Accepted version in Advances in High Energy Physic

Coulomb's law modification driven by a logarithmic electrodynamics

We examine physical aspects for the electric version of a recently proposed logarithmic electrodynamics, for which the electric field of a point-like charge is finite at the origin. It is shown that this electrodynamics displays the vacuum birefringence phenomenon in the presence of external magnetic field. Afterwards we compute the lowest-order modification to the interaction energy by means of the gauge-invariant but path-dependent variables formalism. These are shown to result in a long-range ($1/r^3$-type) correction, in addition to a linear and another logarithmic correction, to the Coulomb potential.Comment: 4 pages. arXiv admin note: text overlap with arXiv:1709.0386

A 3-form Gauge Potential in 5D in connection with a Possible Dark Sector of 4D-Electrodynamics

We here propose a 5-dimensional {\bf Abelian gauge} model based on the mixing between a $U(1)$ potential and an Abelian 3-form field by means of a topological mass term. An extended covariant derivative is introduced to minimally couple a Dirac field to the $U(1)$ potential, while this same covariant derivative non-minimally couples the 3-form field to the charged fermion. A number of properties are discussed in 5D; in particular, the appearance of a topological fermionic current. A 4-dimensional reduced version of the model is investigated and, { \bf in addition to the $U(1)$ electric- and magnetic-sort of fields,} there emerges an extra set of electric- and magnetic-like fields which contribute a negative pressure and may be identified as a possible fraction of dark energy. The role of the topological fermionic current is also contemplated upon dimensional reduction from 5D to 4D. Other issues we present in 4 space-time dimensions are the emergence {\bf of a pseudo-scalar massive particle,} an extra massive neutral gauge boson,{\bf which we interpret as a kind of paraphoton}, and the calculation of spin- and velocity-dependent interparticle potentials associated to the exchange of the intermediate bosonic fields of the model.Comment: -- 30 pages -- L. P. R. Ospedal appears as a new co-author; modifications by inclusion of the gravitational sector and the attainment of a spin- and velocity-dependent potential as an application have been worked out in this Revised Versio

Planejamento de compras na construção civil baseado na curva ABC : um estudo de caso

Orientador : Prof. Marcell MacenoMonografia (especialização) - Universidade Federal do Paraná, Setor de Tecnologia, Curso de Especialização em Gestão de Suprimentos.Inclui referênciasResumo : O mundo dos negócios na indústria brasileira da construção civil tem se mostrado cada vez mais diversificado, complexo e exigente. Apesar de ainda existirem construtoras que não abracem a busca pela melhoria contínua, inovações nos processos produtivos e gerencias e por inovações nos seus produtos. A palavra chave neste século é mudança. Neste contexto, o presente artigo teve por objetivo apresentar uma proposta de melhoria do processo de aquisição de compras na construção civil, por meio da implantação de um planejamento estratégico embasado nos prazos de contratação, levando em consideração os produtos A da curva ABC e a compra proativa, sendo resultado de uma pesquisa exploratória, com aplicação prática caracterizando-se em um estudo de caso. Como resultado, o planejamento possibilitou otimizar os recursos financeiros alocados ao projeto, buscando a qualidade especificada com o melhor custo/ beneficio possível, contribuindo para a evidenciação do tema como fator importante a ser observado nos processos de aquisição das empresas.Abstract : The business world in Brazilian construction industry has proved increasingly diverse, complex and demanding, although there are still construction companies who do not embrace the seeking for continuous improvement, production and managerial innovation processes and innovations in its products. The keyword of this century is change. In this context, this article aims to present a proposal for improving the construction purchasing acquisition process, through the implementation of a strategic planning grounded in the deadline for contracting, taking into account the products A of the ABC analysis and the proactive purchasing, being the result of an exploratory research with practical application being characterized as a study case. As a result, the planning has enabled optimize the financial resources allocated to the project, seeking the specified quality at the best ost/benefit possible, contributing to the theme disclosure as an important factor to be observed in the companies’ acquisition process

The Montana Kaimin, May 14, 1918

Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/1478/thumbnail.jp

Investigations on Effective Electromagnetic and Gravitational Scenarios

The work aims effective and low-dimensional systems. Some different contexts involving gravitational and electromagnetic interactions are investigated. The electromagnetic one approaches bosonic and fermionic Effective Quantum Field Theories non-minimally coupled in three spacetime dimensions submitted to the expansion of Foldy-Wouthuysen Transformation, what generates (non-)relativistic corrections. A study of the effects of an external electromagnetic field derived from the Maxwell-Chern-Simons Electrodynamics on the obtained interactions are executed, as well as the impact produced by the dimensional reduction on expanded higher dimensional fermionic system in comparison to the low-dimensional one. In the scenario of gravitational effective model, scalar and fermionic particle scatterings reveal inter-particles interactions beyond monopole-monopole, leading to velocity and spin contributions, and the results are compared to a modified Electrodynamics effective model. A non-perturbative model resourcing to Casual Dynamics Triangulation data is adopted to serve as consistency check of the potentials resultants. Low-dimensional Maxwell-Higgs effective models with modified kinetic terms are studied, submitting them to a Bogomol'nyi prescription-type for calculation of inferior (non-trivial) bound energy and the self-dual equations. Vortex solutions for gauge field non-specified by an ansatz are achieved and their topological feature detailed

Considerations on the ModMax electrodynamics in the presence of an electric and magnetic background

The properties of the modified Maxwell electrodynamics (ModMax) are investigated in the presence of an external and uniform electromagnetic field. We expand the non-linear theory around an electromagnetic background up to second order in the propagating fields to obtain the permittivity and permeability tensors, the dispersion relations, the group velocity and the refractive index of the wave as functions of the uniform electric and magnetic fields. The case in which these background fields are perpendicular is analyzed. The birefringence phenomenon is discussed where the parameter of the non-linear theory has a fundamental role. We calculate the difference of the refractive indices as function of the ModMax parameter, and of the electric and magnetic fields. Finally, we compute the interaction energy for an axionic ModMax electrodynamics in the presence of an external magnetic background fields, within the framework of the gauge-invariant, but path-dependent variables formalism. Our results show that the interaction energy contains a linear term leading to the confinement of static probe charges.Comment: 10 pages, 2 figure

A Dirac-material-inspired non-linear electrodynamic model

We propose and study the properties of a non-linear electrodynamics that emerges inspired on the physics of Dirac materials. This new electrodynamic model is an extension of the one-loop corrected non-linear effective Lagrangian computed in the work of ref. [3]. In the particular regime of a strong magnetic and a weak electric field, it reduces to the photonic non-linear model worked out by the authors of ref. [3]. We pursue our investigation of the proposed model by analyzing properties of the permittivity and permeability tensors, the energy-momentum tensor and wave propagation effects in presence of a uniform magnetic background. It is shown that the electrodynamics here presented exhibits the vacuum birefringence phenomenon. Subsequently, we calculate the lowest-order modifications to the interaction energy, considering still the presence of a uniform external magnetic field. Our analysis is carried out within the framework of the gauge-invariant but path-dependent variables formalism. The calculation reveals a screened Coulomb-like potential with an effective electric charge that runs with the external magnetic field but, as expected for Dirac-type materials, the screening disappears whenever the external magnetic field is switched off.Comment: 9 pages, 3 figure