Element Segregation in Low Metallicity Stars and the Primordial Lithium   Abundance
  Observational constraints on the primordial lithium abundance are important for the evaluation of the baryonic density of the universe. Its precise determination however suffers from uncertainties due to the possible depletion of this element inside the stars. Here we present and discuss new results on the lithium abundances in pop II stars obtained with most recent stellar models including the best available physics. We show that it is possible to account for the general behavior of lithium observed in pop II stars without any free parameters. Macroscopic motions inside the stars are needed but it is not necessary to specify their exact nature to interpret the observational data. This constatation allows to derive a parameter-free value for the lithium primordial abundance : log(Lip) = 2.35 +/- .10 in the log(H) = 12 scale. 
Sylvie Vauclair and Corinne Charbonnel