Fine tuning problem of the cosmological constant in a generalized Randall-Sundrum model * *Supported by State Key Program of National Natural Science Foundation of China (11535005), the National Natural Science Foundation of China (11647087), the Natural Science Foundation of Yangzhou Polytechnic Institute (201917) and the Natural Science Foundation of Changzhou Institute of Technology (YN1509)

Abstract

To solve the cosmological constant fine tuning problem, we investigate an (n+1)-dimensional generalized Randall-Sundrum brane world scenario with two -branes instead of two 3-branes. Adopting an anisotropic metric ansatz, we obtain the positive effective cosmological constant of order and only require a solution . Meanwhile, both the visible and hidden branes are stable because their tensions are positive. Therefore, the fine tuning problem can be solved quite well. Furthermore, the Hubble parameter as a function of redshift is in good agreement with the cosmic chronometers dataset. The evolution of the universe naturally shifts from deceleration to acceleration. This suggests that the evolution of the universe is intrinsically an extra-dimensional phenomenon. It can be regarded as a dynamic model of dark energy that is driven by the evolution of the extra dimensions on the brane.