Revisitando modelos de inflação híbrida.

Abstract

Solutions which come from nonlinear differential equations are part of the classical field theory, such solutions also remember the behavior of solitary waves and can be stable or unstable. They are also known as defect and called by kinks and lumps when we deal with one-dimensional systems. This dissertation is based on the application of defect like solutions in cosmological quintessence models, such an application can be used to describe the actual phase of an expanding universe. In the end of nineties, two research groups shown independently that the universe is in an accelerated expansion phase, whose mechanism is named by dark energy. There are several theoretical proposals to describe dark energy, among them we highlight the quintessence cosmological models, where an action composed by a scalar field is coupled with the famous Einstein-Hilbert action. Such a coupling takes influence as in the equation of motion for the scalar field, as in the Friedmann equations which come from the minimization of the action is respect to the metric. Consequently, this scalar field has a direct influence in the determination of the cosmological parameters. In this dissertation, we revisited the first order formalism for quintessence models, and we shown how this formalism is essential in the search for analytical hybrid inflation models. We presented a methodology which is capable to build new families of quintessence models, formed by two scalar fields. We studied the cosmological parameters derived from one example, and we verified that they corroborate with the description of different phases of the universe.