Can the phase transition from quark-gluon plasma to hadron-resonance gas affect primordial nucleosynthesis?

We consider a first-order phase transition from a quark-gluon plasma (QGP) to a hadron-resonance gas (HRG) in the early Universe. We use relativistic quantum statistics for particles in both the phases and include Hagedorn's pressure ensemble correction for the finite size of the hadrons in the HRG phase. In our model we can find the pressure, temperature, and baryon-chemical potential equilibria between the QGP phase and the HRG phase even at very large values of the bag constant $B$. The ratio of the baryon-number densities in the QGP and HRG phases at the critical temperature shows that the primordial nucleosynthesis will not be affected significantly if the transition temperature ≳ 125 MeV. The inclusion of sufficiently light strange quarks in the QGP phase leads to an increase in the baryon density contrast.