Universo de Gödel em teorias de gravitação modificadas

Abstract

In this study, we consider a gravity theory involving a spontaneous Lorentz symmetry breaking called the bumblebee model. We show that, at certain values of the bumblebee field, the Gödel metric is consistent within this theory. We also study another proposal for modification of gravitation that consists in adding the Chern-Simons term to the usual gravitation. We show that in this case, we can have the Gödel-type solution on this theory in two special situations: first, we make a choice for the scalar field, so that it has a type dependence = (x; y). In the second situation, we make a particular choice that involves the parameters m and !, parameters that determine the various Gödel-type metrics. Also in the second situation, we observed that the choice made between the parameters m and ! avoids the violation of causality, a fact that occurs in the first case.