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Paper IPM / Physic / 8327  


Abstract:  
We present the generalized Friedmann equations describing the cosmological evolution of a finite thick brane immeresed in a fivedimensional Schwarzschild Antide Sitter spacetime. A linear term in the density in addition to a quatratic one arises in the Friedmann equation, leading to the standard cosmological evolution at late times without introducing an ad hoc tension term for the brane. The effective fourdimensional cosmological constant is then uplifted similar to the KKLT effect and vanishes for a brane thickness equal to the AdS curvature size, up to the third order of the thickness. The fourdimensional gravitational constant is then equal to the fivedimensional one divided by the AdS curvature radius, similar to that derived by dimensional compactification. An accelerating brane cosmology may emerge at late times provided there is either a negative transverse pressure component in the brane energymomentum tensor or the effective brane cosmological constant is positive.
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