Lepton asymmetry and the cosmic QCD transition
  We study the influence of lepton asymmetry on the evolution of the early
Universe. The lepton asymmetry $l$ is poorly constrained by observations and
might be orders of magnitude larger than the baryon asymmetry $b$, $|l|/b \leq
2\times 10^8$. We find that lepton asymmetries that are large compared to the
tiny baryon asymmetry, can influence the dynamics of the QCD phase transition
significantly. The cosmic trajectory in the $\mu_B-T$ phase diagram of strongly
interacting matter becomes a function of lepton (flavour) asymmetry. Large
lepton asymmetry could lead to a cosmic QCD phase transition of first order.
