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Paper IPM / Physic / 17873  


Abstract:  
We expand on the braneworldblack hole de Sitter model introduced in \cite{Rasulian} which is a proposal for constructing an effective de Sitter spacetime with no explicit dependence on brane tension or bulk cosmological constant. In this model the 4D de Sitter space emerges on a brane near the horizon of a 5D black hole. We study the effective gravity on the brane nonperturbatively, with an approximate Z2 symmetry assumption, up to a conformal factor, and find that the evolution of the effective cosmological constant on the brane depends on the flux of energy towards and away from the black hole in the bulk. In this setup the presence of the black hole horizon sets the initial condition for the brane's evolution and the brane approaches its null configuration with de Sitter length $l\lesssim l_5$, where $l_5$ is the 5D Planck's length, as soon as the horizon forms. During the last stages of collapse following this phase (or further flux of matter in the bulk after the horizon is formed), the effective de Sitter length on the brane increases due to the infalling flux relatively fast. This phase is tentatively the transition between a low scale inflationary phase and the late dark energy phase. Also we observe that the increase in the de Sitter length is accompanied with a flux of energy entering the brane due to the jump in the bulk flux across the brane. Considering the initial state of the brane to be in the $l_5$ neighborhood of the horizon, the configuration which is slightly below the horizon is Euclidean AdS with AdS radius $l\lesssim l_5$. This can be interpreted as a boundary proposal for the resulting cosmology.
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