Orientador: Waldyr A. Rodrigues Junior / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Ciencia da Computação / Made available in DSpace on 2018-07-17T19:45:01Z (GMT). No. of bitstreams: 1 Figueiredo_VeraLuciaXavier_D.pdf: 1462432 bytes, checksum: 84e62f3722f17311bf0700d9a7539182 (MD5) Previous issue date: 1987 / Resumo: Este trabalho tem dois objetivos principais. O primeiro consiste em eslcarecer as diferentes definições e representações de spinores que aparecem na literatura, a saber: Spinores covariantes (c-spinor) definidos como elementos de espaços vetoriais complexos, munidos de um "produto escalar" que não invariantes sob a ação de certos grupos Lie ...Observação: O resumo, na íntegra poderá ser visualizado no texto completo da tese digital / Abstract: This thesis have two main purposes. The first is to clear up the different definitions and representations of spinors appearing in the literature. These are: covafitant iptnofiA (c-spinors) defined as elements of complex vector spaces equiped with a "scalar product" which are invariant under the action of certain Lie groups ...Note: The complete abstract is available with the full electronic digital thesis or dissertations / Doutorado / Doutor em Matemática

published_or_final_version / Mathematics / Master / Master of Philosophy

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (p. 86-88). Also available in print.

No description available.

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 96-102). Also available on the World Wide Web.

Orientador: Jose Bellandi Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-21T00:06:24Z (GMT). No. of bitstreams: 1 Fleitas_JulianaRita_M.pdf: 1031600 bytes, checksum: 842744143f91e83439291416afcaa7b0 (MD5) Previous issue date: 1996 / Resumo: Discutimos neste trabalho as soluções para as equações de evolução temporal para um sistema acoplado bidimensional via função de Green, fazendo-se uma aplicação particular dos resultados para o problema de um sistema de dois neutrinos de sabores, quando sujeitos a interação com a matéria solar / Abstract: Not informed. / Mestrado / Física / Mestre em Física

No description available.

The work is centered on the study of dimensionally reduced vector effective field theories from the point of view of soft scalar limits using the spinor-helicity formalism. The Dirac-Born-Infeld model is singled out by its enhanced soft limit at the level of four and six-point amplitudes. In the process, the spinor-helicity formalism is outlined and its use illustrated on explicit examples. The remainder of the work is focused on the corresponding questions in six dimensions. The rel- evant version of spinor-helicity formalism is presented, followed by a discussion of little group invariants and of the (im)possibility of their use on characteriza- tion of theories. Lastly, attempts at formalizing the process of taking the soft limit are made, with inspiration from the four-dimensional case. 1

The primary study of this thesis is the experimental realization of the non-equilibrium dynamics of a quantum inverted pendulum as examined in the collective spin dynamics of a spin-1 Bose-Einstein condensate. In order to compare experimental results with the simulation past the low depletion limit, current simulation techniques needed to be extended to model atomic loss. These extensions show that traditional measurements of the system evolution (e.g. measuring the mean and standard deviation of the evolving quantity) were insufficient in capturing the quantum nature of the evolution. It became necessary to look at higher order moments and cumulants of the distributions in order to capture the quantum fluctuations. Extending the implications of the loss model further, it is possible that the system evolves in a way previously unpredicted. Spin-mixing from a hyperbolic fixed point in the phase space and low noise atom counting form the core of the experiment to measure the evolution of the distributions of the spin populations. The evolution of the system is also compared to its classical analogue, the momentum-shortened inverted pendulum. The other experimental study in this thesis is mapping the mean-field phase space. The mean-field phase space consists of different energy contours that are divided into both phase-winding trajectories and closed orbits. These two regions are divided by a separatrix whose orbit has infinite period. Coherent states can be created fairly accurately within the phase space and allowed to evolve freely. The nature of their subsequent evolution provides the shape of the phase space orbit at that initial condition. From this analysis a prediction of the nature of the entire phase space is possible.

In this thesis we investigate the static, dynamic, and thermodynamic properties of atomic spin-1 Bose gases in external magnetic fields. At low magnetic fields the properties of single-component, or scalar condensates, are essentially unaffected but can become significantly altered for spinor Bose condensates as shown by our studies. We first study the Bose-Einstein condensation of trapped spin-1 Bose gases by employing the Hartree-Fock approximation and the two-fluid model within a mean field approximation. Our detailed investigation reveals that the ferromagnetically interacting spin-1 condensates exhibit triple condensations while the antiferromagnetically interacting ones show double condensations. The ground state structure of homogeneous and trapped spin-1 Bose condensates with ferromagnetic and antiferromagnetic interactions at zero temperature in magnetic fields are then investigated systematically. We further illuminate the important effect of quadratic Zeeman shift which causes a preferred occupation of the $|m_F=0 angle$ state through spin exchange collisions, $2|m_F=0 angle leftrightarrow |m_F=1 angle + |m_F=-1 angle$. We also present detailed studies of the off-equilibrium coherent dynamics of spin-1 Bose condensates in magnetic fields within the single spatial mode approximation. Dynamical instabilities of the off-equilibrium oscillations are shown to be responsible for the formation of multiple domains as recently observed in several $^{87}$Rb experiments. Finally, we discuss briefly excited condensate states, or soliton-like states, in cigar-shaped spin-1 Bose condensates with an effective quasi-1D description, using the developed nonpolynomial Schr"odinger equation.