Um estudo sobre dimensões extras.

Abstract

The space-time seems to have four dimensions according to our common sense. However there are reasons, from the viewpoint of theoretical physics, to believe in the existence of extra dimensions. But if there are extra dimensions, theories must be able to explain how they are hidden from our observation. In this work, we consider some models of higher dimensional theories, trying to establish the main di erence concerning the mechanism used by them in order to hide the extra dimensions. We start with Kaluza-Klein theories which postulate the existence of compact extra dimensions, whose length is of the order of the Planck scale. Then, we study a brane world model, known as ADD model, in which extra dimensions are still compact, but whose scale can be much greater than the Planck length. Finally, in the scenario of warped extra dimensions, we consider the model of only one compact warped dimensions (RSI) and the RSII model, in which the extra dimension has an in nite scale.