Kinks e compactons em teoria de campos a temperatura finita e branas

Abstract

In the present thesis, we study several models in field theory that support localized solutions. We present general properties of classical scalar field theory, highlighting some relevant models in the literature. From this, we use the deformation method to construct two new families of hyperbolic potencials, where several aspests were analysed. We also investigate models that develop dynamics of Dirac- Born- Infeld type, where additional powers arise in the derivatives of the scalar field, which are controlled by a real parameter; so we explore what effects are provoked in the topological solutions. After that, we study how thermal fluctuations, obtained by one-loop correction in the effective potential calculation, can lead to a phase transition on the symmetry of some models. On this perspective, we highlight how thermal effects are able to modify the transition from kinks to compactons, where the results suggest the symmetry restoration at high temperatures. We also present a discussion about branes modelled by scalar fields with an infinity extra dimensiona. Thus, we introduce a mechanism that smoothly transforms a thick brane into a hybrid brane, engendering internal structure.