Oscilador de Dirac: implicações da violação da simetria de Lorentz e da massa dependente da posição

• Autor(a) principal: Cavalcante, Roberto Vinhaes Maluf
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/12541
• topic: Oscilador de Dirac; Simetria de Lorentz; Abordagem de Foldy-Wouthuysen

In this work we study the Dirac Oscillator (DO) in a threefold way. In the first way, we study DO with Lorentz symmetry violation. This violation is implemented through vectorial and an axial terms. We realize a non-relativistic limit and we obtain that the background vector field does not modify the energy spectrum. However, in the case of the background axial field, a correction similar to the Zeeman effect shows up. As the second issue studied here, we report first studies on the Dirac oscillator with variable mass. We impose a constraint in the system in order to preserve a supersymmetric structure and hence to obtain a wave function solution. This condition allows us to find a particular functional form to the mass, which presents an interesting feature. Due to this feature, this model enhances twofold physical equivalence for the Dirac oscillator, namely, an interaction term between an anomalous magnetic moment of neutral fermions and a charged sphere, and the confinement of quarks. Also eigenfunctions and eigenenergy of the fundamental state of the system are obtained. Finally, in the third part of our work, we use the so called Foldy-Wouthuysen approach in order to treat the ordering problem of the kinetic energy operator in the low energy theory. The ordering problem appears in the Schroedinger theory when we consider mass depending on position, since due to the presence of two operators in the kinetic term, the Hamiltonian turns ambiguous. In that work, starting from a Dirac oscillator which mass depends on position, we use the Foldy-Wouthuysen transformation to achieve a non-relativistic anti-Hermitian Hamiltonian with no ordering problem. As a matter of completeness we add two appendix, namely, an appendix A in order to present the confluent hypergeometric equation and their relations with special functions, and an appendix B, where we review briefly the Supersymmetric Quantum Mechanics.