Quantum Field Theory
Mostrando 13-24 de 98 artigos, teses e dissertações.
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13. Direito quântico: revisitação e hipóteses de aplicação ao direito contemporâneo
After almost five centuries since the Scientific Revolution, the symptoms of a severe paradigmatic change are finally visible to the eyes of science. Until then, the mechanicist model that lead the scientific attitude was based on general laws os nature, which were able to determine the behaviour of beings in any given space and time. Its epistemological pre
Publicado em: 2010
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14. A topologia molecular QTAIM e a descrição mecânico-quântica de ligações de hidrogênio e ligações de di-hidrogênio
Hydrogen bonds formed through the interaction between a high electronic density center (lone electron pairs, π or pseudo-π bonds) and proton donors cause important electronic and vibrational phenomena in many systems. However, it was demonstrated that proton donors interact with hydrides, such as alkali and alkaline earth metals (BeH2, MgH2, LiH and NaH),
Química Nova. Publicado em: 2010
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15. On the inverse problem in high-energy elastic hadron scattering and the applicability of a representation for the real part of the amplitude / Um estudo sobre o problema inverso do espalhamento elastico de hadrons em altas energias e a aplicabilidade de uma representacao para a parte real da amplitude
The theoretical description of high-energy elastic hadron scattering constitutes an open problem in both, the underlying quantum field theory of strong interactions (QCD) and the phenomenological context. In this work the inverse problem in elastic hadron scattering is discussed in the impact parameter and eikonal frameworks, specifically a study on the empi
Publicado em: 2010
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16. Pode a não-comutatividade do espaço indicar a dependência funcional da entropia com a área
Calculation of the entropy of black holes is an open subject. Such problem is very interesting due to its relationship with basic problems like; the construction of a quantum theory of the gravity, statistical approach of the calculation of black holes entropy and the validity (or non validity) of the holographic principle. In this work we are looking for a
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 22/10/2009
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17. Gupta-Bleuler quantization for massive and massless free vector fields
It is shown that the usual quantum field theory leads to an ultraviolet divergence in the vacuum energies and an infrared divergence in the two-point functions of the massive and massless vector fields. Using a new method of quantization it is shown that the vacuum energies converge, and the normal ordering procedure is not necessary. Also the propagators ar
Brazilian Journal of Physics. Publicado em: 2009-09
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18. Paralelo entre as teorias quântica e semi-clássica da interação átomo-campo no modelo Jaynes-Cummings
We studied a very simple model of the interaction between radiation and matter, named Jaynes-Cummings model. Matter is represented by an atom, treated as a two level system, which interacts with one single mode of the electromagnetic field. We looked at the problem in two different ways: first, treating both systems as quantum and later, considering the fiel
Publicado em: 2009
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19. Lorente symmetry breaking and chern-simons term in (3+1) dimensions / Quebra da simetria de Lorentz e o termo de Chern-Simons em (3+1) dimensões
In this dissertation, we studied the Chern-Simons model in the gauge and the gravitation theories. So, we study the problem of fermions interacting, in a first moment, with a electromagnetic field and in a second moment, with a gravitational field. We introduced in the interaction lagragian, for both cases, a background field which break the Lorentz symmetry
Publicado em: 2009
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20. Magnetotransporte em poços-quânticos de AlGaAs/GaAs com diferentes formas de potencial / Magnetotransport in AlGzAs/GzAs quantum wells with different potential shapes
In this thesis we present studies of magnetotransport in double quantum wells (DQWs) in low magnetic fields and under application of an external electric field (gate potential). Measurements of magnetoresistance have been carried out in both linear and non-linear regime. We report on the observation of magneto-intersubband (MIS) oscillations for the first ti
Publicado em: 2009
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21. EstatÃstica de contagem de carga e efeitos de interferÃncia em sistemas mesoscÃpicos
In this thesis we presented a detailed study about full counting statistics of transmitted charge and accumulated phase and the quantum interference corrections to the average conductance and the average shot-noise power in non-ideal ballistic chaotic cavities. In the theoretical analysis of this mesoscopic system, we obtained analytical expressions for the
Publicado em: 2009
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22. Análogos cosmológicos dos efeitos Schwinger estático e oscilatório / Cosmological Analogues of the Static and Oscillatory Schwinger Effect
In this work we study the quantum effects of particle creation in the cosmological context and of the classical electrodynamics. With the studies of the particle creation in constant and oscillatory external electrical fields, the known static and oscillatory Schwinger effects, respectively, it was possible to study the polarization of the quantum vacuum and
Publicado em: 2009
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23. Extended Bell´s Be-ables and Atenuattion × Amplification Competition. / Extensão dos Be-ables de Bell e Competição Atenuação x Amplificação
In the first part of this work we employ the Itô stochastic equation to extend Bells be-able interpretation of quantum mechanics to encompass dissipation, decoherence and quantum-to-classical transition through quantum trajectories. For a particular choice of the source of stochasticity, the one leading to a dissipative Lindblad type correction to the Hamil
Publicado em: 2009
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24. CIÊNCIA E TÉCNICA EM HEIDEGGER E HEISENBERG / SCIENCE AND TECHNIQUE IN HEIDEGGER AND HEISENBERG
The classical physical science distinguishes itself as a previous project, consisting of the fundamental concepts of elements such as calculation, time, space, motion, matter, force and directed to capture all the nature phenomena supposedly unified. Quantum mechanics advances beyond these postulates, evidencing the inevitable interference of the subject in
Publicado em: 2009