Particle fractions computed at T = 0 in neutrinoless β-equilibrium for three different EOS: BLh (left), DD2 (centre), and SFHo (right). Black lines show the electron fraction computed in two different cases: equilibrium with muons (solid lines) or without muons (dashed lines). The green line corresponds to the fraction of protons at equilibrium with muons, while the red line corresponds to the muon fraction. We note that when muons are not included, the proton fraction coincides with the electron one (dashed black line).