Pionic BEC--BCS crossover at finite isospin chemical potential

TL;DR

This paper investigates the transition from bosonic pionic condensation to fermionic Cooper pairing at finite isospin chemical potential using the linear sigma model, revealing a gradual crossover from bosonic to fermionic dominance.

Contribution

It introduces a model to describe the pionic BEC-BCS crossover at finite isospin chemical potential, highlighting the evolution from bosonic to fermionic pairing in quark matter.

Findings

Pionic condensation is purely bosonic at low isospin chemical potential.

Gradual emergence of q-ar q pairing as isospin chemical potential increases.

The q-ar q pairing is weakly coupled compared to q-q pairing in color superconductivity.

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.