Aspectos de gravitação em cenários de branas espessas em seis dimensões

Abstract

The braneworld hypothesis has changed the way we understand the Universe introducing the idea that it may be thought as a hypersurface embedded in a higher dimensional bulk space-time. The braneworld concept emerged from string theory and unification models and yelds good explanations to several fundamental phenomena in High Energy Physics such as the hierarchy problem, the dark matter origem, the small value of the cosmological constant and the cosmic acceleration. In the first proposal of this thesis we analyze a static and axisymmetric braneworld in six dimensional as a string-like model extension. For a subtle warp fanction, this scenario provides near brane corrections. By varying the bulk cosmological constant, we obtain a source which passes through different phases. The solution is defined both for the interior and for the exterior of the string and stisfies all the energy conditions. A smoothed gravitational massless mode is localized on the brane, of which the core is displaced from the origin. In contrast to the thin-string model, the massive solutions have a high amplitude near the brane. furthermore, by means of an analog quantum potencial analysis, we show that only s-wave gravitational Kaluza-Klein modes are permissible. In the second proposal of this work we derive an expression for the correction in the Newton’s law of gravitation due to the gravitational Kaluza-Klein states in a general thick string-like braneworld scenario in six dimensions. In order to analyze corrections to Newton’s law study the gravity fluctuations in a 3-brane placed in a transverse resolved conifold and use suitable numerical methods to attain the massive spectrum and the corresponding eigenfunctions. Moreover, gravitational massless mode is localized on the brane recovering 4−D gravity. Finally, for the singular conifold, we found that a non-frist eigenstate is a resonant mode. Such excited state is the largest contributor to corrections in the Newtonian potential.