QCD at a Finite isospin density: From the pion to quark-antiquark condensation

By Dam Thanh Son, M. Stephanov. 2000

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QCD at a finite isospin chemical potential μI is studied. This theory has no fermion-sign problem and can be simulated on a lattice by using present-day techniques. We solve this theory analytically in two limits: low μI, where chiral perturbation theory is applicable, and asymptotically high μI, where perturbative QCD is at work. At a low isospin density, the ground state is a superfluid pion condensate. At a very high density, it is a Fermi liquid with Cooper pairing. The pairs carry the same quantum numbers as the pions. Motivated by this observation, we put forward a conjecture that the transition from hadron to quark matter is smooth. The conjecture passes several nontrivial tests. Our results imply a nontrivial phase diagram in the space of the temperature and chemical potentials of isospin and baryon number. At asymptotically large values of μI and small values of the baryon chemical potential, the ground state is in a phase similar to the Fulde-Ferrell-Larkin-Ovchinnikov phase. It is characterized by a spatially modulated superfluid order parameter 〈ūγ5d〉 and may be the asymptotic limit of the inhomogeneous pion-condensation phase advocated by Migdal and others.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/70d4ccf2f5e3189b2df64bc796ea54d441bdc6e6

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In Astronomy and Astrophysics

In Nuclear and High Energy Physics

Citations in the corpus

Flavor superconductivity from gauge/gravity duality (2009, result): “For pions, similar results have been found within QCD: There are analytical results for small and very large isospin chemical potential using the chiral Lagrangian [40, 41], as well as lattice results [42].”