Navegando por Autor "SIMAS, Fabiano de Carvalho"

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    Armadilhamento de Campos de Spin-0 em um Anel imerso em (3,1) dimensões
    (Universidade Federal do Maranhão, 2011-08-29) SIMAS, Fabiano de Carvalho; SANTOS FILHO, Adalto Rodrigues Gomes dos; 136440738-80; http://lattes.cnpq.br/9485040610659823
    In this work we consider rings constructed with a scalar field ϕ with radial symmetry embedded in the (3, 1) Minkowski spacetime. Such topological defects have radius and thickness related to the energy density and can be attained from a lagrangian density explicitly dependent with the distance,which can be interpreted as an effective theory from a more fundamental model. Neglecting the backreaction on a weak scalar field Φ coupled with the strong field ϕ, a standard mode decomposition leads to a standard action for one-dimensional Klein-Gordon fields living along the ring axis and a two-dimensional Schr¨odinger-like equation, describing massive spin-0 particles. A specific choice of the coupling between the scalar fields Φ and ϕ is able to transform the Schr¨odinger-like equation in a one-dimensional form depending on the radial distance. The interaction is compatible with a repulsive character of the core of the ring and with the presence of resonances around the ring radius. The presence of tachyonic and physical modes are described in a phase space diagram, which is confronted with the numerical analysis of the massive modes. It is found that, for the scale of rings considered, larger radius favor the localization process, and for small radius the leaking of the massive modes is compatible with a repulsive interaction acting between the rings walls and the massive spin-0 particles.
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    Vórtices BPS no modelo de Maxwell- CP(2) com estrutura interna
    (Universidade Federal do Maranhão, 2019-04-23) ANDRADE, João Luís Brandão; SANTOS, Carlos Eduardo da Hora; 943294943-53; http://lattes.cnpq.br/3418148094049270; SANTOS, Carlos Eduardo da Hora; 943294943-53; http://lattes.cnpq.br/3418148094049270; SIFUENTES, Rodolfo Alván Casana; http://lattes.cnpq.br/6508618435773438; SIMAS, Fabiano de Carvalho; http://lattes.cnpq.br/1410695036306945
    In this dissertation, I present the original BPS vortices (Bogomol'nyi-Prasad-Sommer)eld) inherent in a gauge model Maxwell-CP(2) from the general scenario CP (N-1) (in which N = 3, with N corresponding to the number of components of the CP (2) field), when subjected to the presence of an additional, real and neutral scalar field. Then, focusing on radially symmetrical structures, we construct a first-order structure for the model, using the Bogomol'nyi procedure. From the minimization of the total energy, we obtain general expressions for the minimum energy of the model, whose value has an extra contribution due to the presence of the neutral field, and for the respective first order equations (BPS equations), in which both the minimum energy while the BPS equations depend directly on the functional structure of the dielectric function. The introduction of the scalar field, which interacts with the electromagnetic sector via an unusual dielectric function, produces significant modifications in the shape of the resulting BPS vortices, such changes being understood as the manifestation of internal structures originated by the presence of the additional neutral field.