Cosmological test of Brane models

After obtaining a class of solutions for two-brane models we show that at the epoch of Primordial Nucleosynthesis, they have an unconventional cosmology which modifies the He-4 yield with respect to the BBN prediction. This reconciles the relatively high baryonic density suggested from CMB anisotropy observations and the observed low primordial He-4 yield. We also perform a second test using Ultra High Energy Cosmic Rays (UHECR). If at high energies particles penetrate into the bulk, the observed time coherence of the air showers from UHECR constraints the parameter space of the brane world models.