A QCD phase transition in the early universe could have left inhomogeneities
in the baryon to photon ratio and in isospin that might have affected
nucleosynthesis later on. At very high temperature QCD plasma can be described
by perturbation theory because of asymptotic freedom, but a possible phase
transition requires a nonperturbative approach like lattice gauge theory.
Assuming that a first order transition did occur, a dynamical set of equations
can be solved to evolve the universe through it and to quantify the scale of
inhomogeneity. Unfortunately this scale appears to be too small by two orders
of magnitude to affect nucleosynthesis.Comment: 19 pages, 9 figures. To appear in the proceedings of the
International School of Astrophysics D. Chalonge, 8th Course, "Phase
Transitions in the Early Universe: Theory and Observations", Erice, Sicily,
6-17 December 2000, ed. H.J. de Vega, I. Khalatnikov, N. Sanchez (Kluwer
Academic Pub.
