Gabriel German, Alfredo Herrera-Aguilar, Dagoberto Malagon-Morejon, Refugio Rigel Mora-Luna, Roldao da Rocha
Among the multiple 5D thick braneworld models that have been proposed in the last years in order to address several open problems in modern physics, there is one that involves a tachyonic bulk scalar field. In this framework we study a thick braneworld with a cosmological background induced on the brane. It turns out that the field equations derived from the model with a warped 5D geometry are highly non-linear equations that admit a non-trivial solution for the warp factor and the tachyon scalar field with a de Sitter 4D cosmological background. Moreover, the non-linear tachyonic scalar field, that generates the brane in complicity with warped gravity, has the form of a kink-like configuration. However, the non-linear field equations' restricting character does not allow one to easily find thick brane solutions with a decaying warp factor which leads to the localization of 4D gravity and other matter fields. We manage to obtain such a thick brane configuration in this tachyon-gravity setup. When analyzing the spectrum of gravity fluctuations in the transverse traceless sector we show that 4D gravity is localized due to the presence of a {\it single} zero mode bound state separated by a continuum of massive Kaluza-Klein (KK) modes by a mass gap. This is in contrast with previous results where there is a KK massive bound excitation that has no clear physical interpretation. The mass gap is determined by the scale of the metric parameter 'b'. We finally compute the corrections to Newton's law in this model and show that they exponentially decay and coincide with corrections reported in previous results within similar braneworlds with induced 4D de Sitter metric.
View original:
http://arxiv.org/abs/1210.0721
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