We discuss the primordial nucleosynthesis in lepton asymmetric Universe models. In order to better estimate the universal baryon-mass density parameter $\Omega_b$, we try to remove the uncertainty from the theoretical prediction of primordial $^7$Li abundance. We propose a new method to determine the primordial $^7$Li by the use of isotopic abundance ratio $^7$Li/$^6$Li in the interstellar medium which exhibits the minimum effects of the stellar processes.
Categories: astro-ph