Pionic BEC--BCS crossover at finite isospin chemical potential

We study the character change of the pionic condensation at finite isospin chemical potential \mu_$\mathrm{I}$ by adopting the linear sigma model as a non-local interaction between quarks. At low |\mu_$\mathrm{I}$| the condensation is purely bosonic, then the Cooper pairing around the Fermi surface grows gradually as |\mu_$\mathrm{I}$| increases. This q-\bar q pairing is weakly coupled in comparison with the case of the q-q pairing that leads to color superconductivity.