Transições de fase em sistemas de campos escalares complexos: uma análise via teoria de perturbação otimizada

• Autor(a) principal: Silva, Manuella Corrêa e
• Data de Publicação: 2022
• Outros Autores: [e-mail]
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/18720
• topic: Phase transformations (Statistical physics); Broken symmetry (Physics); Perturbation (Quantum dynamics); Quantum field theory; Phase transitions; QFT; Finite temperature; Optimized perturbation theory; Transformações de fase (Física estatística); Simetria quebrada (Física); Perturbação (Dinâmica quântica); Teoria quântica de campos; Transições de fase; TQC; Temperatura finita; Teoria de perturbação otimizada; CIENCIAS EXATAS E DA TERRA::FISICA::FISICA DAS PARTICULAS ELEMENTARES E CAMPOS

It is known that most physical systems acquire greater symmetry at high temperatures. However, the aim of this dissertation is to investigate the phase transitions in physical systems that present inverse symmetry breaking (ISB) and symmetry nonrestoration (SNR). We first developed the theory using perturbation theory. However, this method breaks at high temperatures or densities when the powers of the coupling constants are exceeded by the powers of temperatures. In this way, the ISB or the SNR might just be a consequence of this non-applicability of the perturbation theory. An alternative is to use a non-perturbative method. Here we will use the Optimized Perturbation Theory (OPT), with the Principle of Minimal Sensitivity (PMS), to fix the basic variational parameters that are required by the OPT method. In this dissertation we work with two interacting complex scalar fields and with interaction between then. We consider the effects of finite temperature and chemical potential, comparing the perturbative and non-perturbative results that the finite density effects can bring in both methods. We calculated the 1-loop effective potential effects in the perturbative case and in first order in OPT case and analyzed the ISB and SNR phenomena in the context of both methods.