Doutorado em Física

URI Permanente para esta coleção

http://repositorio.ufes.br/handle/10/17493

Nível: Doutorado
Ano de início: 2003
Conceito atual na CAPES: 4
Ato normativo: Parecer CES/CNE nº 487/2018, homologado pela Port. MEC 609, publicado no DOU em 18/03/2019.
Periodicidade de seleção: Semestral
Área(s) de concentração: Física
Url do curso: https://fisica.ufes.br/pt-br/pos-graduacao/PPGFis/detalhes-do-curso?id=1509

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Navegando Doutorado em Física por Autor "Alvarenga, Flavio Gimenes"

Agora exibindo 1 - 3 de 3
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    Modelos cosmológicos quânticos com fluido perfeito
    (Universidade Federal do Espírito Santo, 2018-10-25) Fracalossi, Raphael; Alvarenga, Flavio Gimenes; Gonçalves, Sergio Vitorino de Borba; Constantinidis, Clisthenis Ponce; Lourenço, José André; Lemos, Nivaldo Agostinho
    In this work, quantum cosmological models with perfect fluid are studied according to the canonical approach of Quantum Cosmology. The material content of the Universe is described by Schutz’s formalism, which is discussed in detail and used as a tool in order to solve the problem of absence of a time variable in theory. In this context, two models are constructed containing a stiff matter fluid. In the first one, a two-fluid model, stiff matter and radiation in a homogeneous and isotropic Universe described by FLRW metric. It is observed that the initial singularity in the classic model is apparently removed in the quantum approach. In the second, an anisotropic quantum cosmological model described by Kantowski-Sachs metric is discussed. As a result, it is found that although the Hamiltonian operator associated with the model is symmetric, the norm of wave function of Universe is time-dependent, implying loss of unitarity, reinforcing the existence of a pathology already verified in quantum cosmological model described by Bianchi I anisotropic metric.
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    Perturbações cosmológicas de origens quântica e clássica : oscilações no espectro de potência e o condensado de Bose-Einstein
    (Universidade Federal do Espírito Santo, 2014-09-24) Freitas, Rodolfo Camargo de; Gonçalves, Sergio Vitorino de Borba; Constantinidis, Clisthenis Ponce; Alvarenga, Flavio Gimenes; Martins, Gabriel Luchini; Monerat, Germano Amaral; Piattella, Oliver Fabio
    The relativistic perturbations of quantum origin are the “seeds” that evolved into the large scale structures throughout classical gravitational instabilities. We study the gauge invariant formalism for the cosmological perturbations and we apply into a two fields model, where one of them suffers a gain of mass, that causes a sharp turn in the fields trajectory, resulting in oscillations of the primordial power spectrum with amplitudes bounded by the observational data. We also study the structure formation within a dark matter model, where dark matter particles are described by a Bose-Einstein condensate
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    Quantização do modelo de Jackiw-Teitelboim no gauge temporal via o formalismo de laços
    (Universidade Federal do Espírito Santo, 2009-06-30) Lourenço, José André; Constantinidis, Clisthenis Ponce; Piguet, Olivier; Franco, Daniel Heber Theodoro; Alvarenga, Flavio Gimenes; Sotkov, Galen Mihaylov; Pinto Neto, Nelson; Constantinidis, Clisthenis Ponce; Piguet, Olivier
    In this work we study the Jackiw-Teitelboim model (JT model), as a model that has the structure of a topological theory of the BF type. In two dimensional space-time, gravitation can be seen as a gauge theory characterized by the Poincaré group ISO(1, 1). As this group, doesn't admit an invariant and nondegenerate quadratic form, the JT model is based on the (Anti)- de Sitter group (A)dS , the group SO(2, 1), which contains the Lorentz group as a subgroup and corresponds to a gravitation theory with a cosmological constant. We see then, that the (A)dS group, taken as a gauge group, contains naturally the di eomorphism symmetry. In this line we investigate the canonical formulation of the JT model in order to quantize it through the formalism of loop quantum gravity (LQG). Following Dirac's program of canonical quantization applied to the loop formalism, we obtain a quantum con guration space starting from the Bohr compacti cation of the real line, we build the respective kinematic Hilbert space and we de ne in a consistent way the volume operator. Finally, we treat the dynamics of the model at the quantum level through the implementation of the constraints originating from the classical theory of the JT model in the temporal gauge in an appropriate Hilbert space.