Gravity localization on intersecting thick braneworlds

Abstract

The localization of gravity for ($5+1$)-dimensional intersecting thick braneworld models is thoroughly investigated. Departing from preliminary results for five independent proposals, from $I$ to $V$, gravity is shown to be localized in the brane. In particular, for models from $I$ to $III$, only the zero modes are analytically determined. On the other hand, for models $IV$ and $V$, massive modes are all obtained: a finite number of massive states is identified for model $IV$, while an infinite but discrete number of massive states bounded from below is exhibited by model $V$. Considering that the discreteness of the graviton modes implies that gravity does not propagate in the codimensions, the naked singularities of models $IV$ and $V$, at edges of space, are made harmless. To conclude, the phenomenological implications for sphere models, constructed out of models $III$ and $IV$, are also discussed. According to such an overall classification, if the internal space is a sphere, model $IV$ is shown to exhibit normalizable modes. More relevantly, for the sphere model assembled out of model $III$, the subtle property of reproducing a consistent Newtonian limit is identified.