Pionic BEC--BCS crossover at finite isospin chemical potential

Abstract

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.

Comments: 17 pages, 3 figures, typos in eq.(6) and refs.[37] and [41] are corrected, published in Phys. Rev. D