Massless Scalar Field
Mostrando 1-12 de 12 artigos, teses e dissertações.
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1. Effective cosmology a la Brans-Dicke with a non-minimally coupling massive inflaton field interacting with minimally coupling massless field
We discuss an effective cosmology a la Brans-Dicke with two interacting scalar fields: a non-minimally coupling massive inflaton Higgs-like scalar field Φ interacting with a minimally coupling massless scalar field χ. Several features are observed and discussed in some details.
Brazilian Journal of Physics. Publicado em: 2010-09
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2. Sobre alguns efeitos quânticos no espaço-tempo de Schwarzschild-de Sitter
In this dissertation we investigate some aspects related with normal modes for scalar fields perturbations of a Schwarzshild-de Sitter black hole. The role played by the cosmological constant A on the reflection and transmission coefficients is studied and analyzed. We also study the Casimir energy density for a massless scalar field confined between two nea
Publicado em: 2009
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3. Espalhamento e absorção de campos bosônicos por buracos negros estáticos e análogos / Scattering and absorption of bosonic fields by static blach holes and analogues
Nesta tese apresentamos a análise da absorção e do espalhamento de partículas não massivas de spins 0 e 1 por buracos negros de Schwarzschild, assim como a absorção e espalhamento por análogos acústicos destes buracos negros. Apresentamos também a análise da absorção e do espalhamento do campo escalar não massivo por buracos negros de Reissner-
Publicado em: 2009
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4. Seção de choque de absorção de buracos negros de Schwarzschild e de buracos acústicos canônicos / Section of shock of absorption of black holes of Schwarzschild and of canonical acoustic holes
In this dissertation we compute the absorption cross section of Schwarzschild black holes for the massless scalar and electromagnetic fields. We also compute the absorption cross section of canonical acoustic holes for sound waves. We use a numerical method to obtain the results in arbitrary frequencies. We also obtain analytic expressions for the low- and h
Publicado em: 2008
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5. O efeito Casimir dinâmico e decoerência
In this thesis we first demonstrate that the inevitable action of the environment can be substantially weakened when considering appropriate nonstationary quantum systems. Beyond protecting quantum states against decoherence, an oscillating frequency can be engineered to make the system-reservoir coupling almost negligible. Differently from the program for e
Publicado em: 2008
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6. Numerical simulations of the gravitational collapse of a massless scalar field / Simulações numericas do colapso gravitacional de um campo escalar sem massa
Esta dissertação trata de um problema de colapso gravitacional do campo escalar sem massa com simetria esférica, de acordo com as equações de Einstein com acoplamento mínimo. Desenvolvemos algoritmos simples mas com ajuste automático de refinamento para obter soluções numéricas. O refinamento é necessário para descrever os fenômenos do colapso.
Publicado em: 2007
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7. An euclidean approach as a method to study the Unruh effect / Uma estratégia euclidiana para o estudo do efeito Unruh
This paper proposes a Euclidean strategy to understand the Unruh effect. On that ground we first study it for free massless scalar fields the way it is usually presented to pliysicists, which is closer to Unruhs original work [32]. Then we infer the effect from an algebraic perspective. We study the proprieties and definitions of KklS states in order to unde
Publicado em: 2007
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8. Decaimentos de neutrinos induzidos por escalares e aplicações a supernovas / Neutrinos decays via scalars and their applications to supernovas
In this work we study nonradiative decays of Majorona neutrinos, via massless bosons, in vacuum and matter. The considerate couplings between the neutrinos and the bosons were scalar and pseudoscalar. In particular we study the processes n i ® nj + c e n i ® n j + c (where is either scalar or pseudoscalar field). In vacuum, we calculate effective rates in
Publicado em: 2006
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9. Boundary conditions as mass generation mechanism for real scalar fields
We consider the effects of homogeneous Dirichlet's boundary conditions on two infinite parallel plane surfaces separated by some small distance a. We find that although spontaneous symmetry breaking does not occur for the theory of a massless, quartically self-interacting real scalar field, the theory becomes a theory of a massive scalar field.
Brazilian Journal of Physics. Publicado em: 2002-09
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10. Scalar field cosmology in three-dimensions
We study an analytical solution to the Einstein's equations in 2 + 1-dimensions. The space-time is dynamical and has a line symmetry. The matter content is a minimally coupled, massless, scalar field. Depending on the value of certain parameters, this solution represents three distinct space-times. The first one is at space-time. Then, we have a big bang mod
Braz. J. Phys.. Publicado em: 2001-09
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11. Critical Phenomena in Gravitational Collapse: The Studies So Far
Studies of black hole formation from gravitational collapse have revealed interesting non-linear phenomena at the threshold of black hole formation. In particular, in 1993 Choptuik studied the collapse of a massless scalar field with spherical symmetry and found some behaviour, which is quite similar to the critical phenomena well-known in Statistical Mechan
Brazilian Journal of Physics. Publicado em: 2001-06
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12. Self-adjointness of the Fourier expansion of quantized interaction field Lagrangians
Regularity properties significantly stronger than were previously known are developed for four-dimensional non-linear conformally invariant quantized fields. The Fourier coefficients of the interaction Lagrangian in the interaction representation—i.e., evaluated after substitution of the associated quantized free field—is a densely defined operator on th