Minkowski Brane in Asymptotic dS$_5$ Spacetime without Fine-tuning
  We discuss properties of a 3-brane in an asymptotic 5-dimensional de-Sitter spacetime. It is found that a Minkowski solution can be obtained without fine-tuning. In the model, the tiny observed positive cosmological constant is interpreted as a curvature of 5-dimensional manifold, but the Minkowski spacetime, where we live, is a natural 3-brane perpendicular to the fifth coordinate axis. 
Zhe Chang, Shao-Xia Chen, and Xin-Bing Huang