Effective Theories for 2+1 Dimensional Non-Abelian Topological Spin Liquids

In this work we propose an effective low-energy theory for a large class of 2+1 dimensional non-Abelian topological spin liquids whose edge states are conformal degrees of freedom with central charges corresponding to the coset structure $su(2)_k\oplus su(2)_{k'}/su(2)_{k+k'}$. For particular values of $k'$ it furnishes the series for unitary minimal and superconformal models. These gapped phases were recently suggested to be obtained from an array of one-dimensional coupled quantum wires. In doing so we provide an explicit relationship between two distinct approaches: quantum wires and Chern-Simons bulk theory. We firstly make a direct connection between the interacting quantum wires and the corresponding conformal field theory at the edges, which turns out to be given in terms of chiral gauged WZW models. Relying on the bulk-edge correspondence we are able to construct the underlying non-Abelian Chern-Simons effective field theory.Comment: 41 pages, 5 figures, typos corrected, references added, published versio

Probing the Effects of Lorentz-Symmetry Violating Chern-Simons and Ricci-Cotton Terms in Higher Derivative Gravity

The combined effects of the Lorentz-symmetry violating Chern-Simons and Ricci-Cotton actions are investigated for the Einstein-Hilbert gravity in the second order formalism modified by higher derivative terms, and their consequences on the spectrum of excitations are analyzed. We follow the lines of previous works and build up an orthonormal basis of operators that splits the fundamental fields according to their individual degrees of freedom. With this new basis, the attainment of the propagators is remarkably simplified and the identification of the physical and unphysical modes gets a new insight. Our conclusion is that the only tachyon- and ghost-free model is the Einstein-Hilbert action added up by the Chern-Simons term with a time-like vector of the type $v^{\mu} = (\mu,\vec{0})$. Spectral consistency imposes taht the Ricci-Cotton term must be switched off. We then infer that gravity with Lorentz-symmetry violation imposes a drastically different constraint on the background if compared to usual gauge theories whenever conditions for suppression of tachyons and ghosts are required.Comment: 15 pages. It coincides with the version published in Phys. Rev.

Preparação e avaliação de formulações termoplásticas com aditivos fotoluminescentes para aplicação em coberturas rígidas utilizadas na manutenção de redes energizadas

Orientadora: Profª. Drª. Marilda MunaroCoorientador: Prof. Dr. Edemir Luiz KowalskiDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia e Ciência dos Materiais - PIPE. Defesa: Curitiba, 19/08/2013Inclui referênciasÁrea de concentração: Engenharia e ciência de materiaisResumo: Nas grandes cidades Brasileiras o movimento de pedestres e veículos às vezes dificulta e até mesmo impede a realização dos serviços de manutenção com a rede energizada. Sendo assim, algumas concessionárias distribuidoras de energia elétrica vem realizando estudos para a viabilização do serviço de manutenção com a rede energizada no período noturno. Na manutenção com a rede energizada utilizam-se equipamentos de proteção individual (EPI's) e equipamentos de proteção coletiva (EPC's), que para aplicação noturna deveriam ter características fluorescentes e/ou fosforescentes para facilitar a localização e garantir a segurança dos eletricistas. Neste trabalho foram avaliadas as propriedades mecânicas e elétricas do polietileno de alta densidade com aditivos fosforescente e/ou fluorescente. Para a avaliação das propriedades mecânica foram realizados ensaios de tração mecânica, análise termodinâmica mecânica, onde foram obtidos os limites de resistência à tração e as relaxações observadas nos polímeros. Nos ensaios elétricos foram realizadas medidas de corrente de despolarização, resistividade superficial e volumétrica, tensão elétrica aplicada em corrente alternada, tensão de ruptura dielétrica e medida de corrente elétrica de despolarização termicamente estimulada. Os resultados obtidos mostraram que a inserção do aditivo fosforescente ou fluorescente no polietileno de alta densidade com aditivo antioxidante não compromete as características mecânicas e elétricas do polímero. E que as porcentagens de 2% e 8% de aditivo fotoluminescente podem ser aplicadas na confecção de EPC's, tais como as coberturas rígidas.Abstract: In large brazilian cities pedestrian movement and vehicle sometimes hinders and even prevents the realization of maintenance services to the network energized. Thus, some electricity distributors have been studying the feasibility of maintenance to the network energized at night. For maintenance services with the energized network are used personal protective equipment (PPE) and collective protective equipment (CPE), however for this application they should have features fluorescent and / or phosphorescent to facilitate the location and ensure the safety of electricians. In this work, the mechanical and electrical properties of high density polyethylene with additives phosphorescent and / or fluorescent were evaluated. For the evaluation of mechanical properties were performed tensile test, dynamic mechanical analysis, where the tensile strength limits and relaxations were obtained. In electrical tests were measured depolarization current, surface and volumetric resistivity, electric voltage alternating current, breakdown voltage and electric current measured thermally stimulated depolarization were measured. It was observed that the inclusion of fluorescent or phosphorescent additive in high density polyethylene with an antioxidant additive not changes significantly the mechanical and electrical characteristics of the polymer, and the percentages of 2 % and 8 % additive photoluminescent may be apply in the manufacture of these equipment