  We investigate how a lepton asymmetry impacts the cosmic trajectory in the
QCD phase diagram. We study the evolution of chemical potentials during the QCD
epoch of the early Universe using susceptibilities from lattice QCD to
interpolate between an ideal quark gas and an ideal hadron resonance gas. The
lepton asymmetry affects the evolution of all chemical potentials. The standard
cosmic trajectory is obtained assuming tiny lepton and baryon asymmetries. For
larger lepton asymmetry, the charge chemical potential exceeds the baryon
chemical potential before pion annihilation.
