Functional renormalization group at finite density and Bose condensation

2010/09/30 by Eirik Eik Svanes, Eirik E. Svanes, Jens O. Andersen
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #High-Energy Particle Collisions Research #Quantum Chromodynamics and Particle Interactions #hep-ph

paper · pdf · doi:10.1016/j.nuclphysa.2011.03.007

published as Nucl.Phys.A857:16-28,2011 · 14 pages. 5 Figs. 2nd version matches published version. Fig.3 improved. Refs. added. Typos fixed

arxiv created 2011/03/31 · openalex publication_date 2011/04/14 · arxiv updated 2011/04/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We discuss the functional renormalization group and pion condensation in the presence of a finite isospin chemical potential μ_I. We calculate the phase diagram as function of temperature T and μ_I. While the exact effective average action is invariant under certain gauge transformations, the effective action in the local-potential approximation is not. As a consequence, the critical chemical potential μ_I^c for Bose-Einstein condensation at T=0 is no longer equal to the mass of the condensing mode. We discuss possible solutions to this problem.

Citations

• Coupling of pion condensate, chiral condensate, and Polyakov loop in an extended Nambu–Jona-Lasinio model
• Low-Energy Quantum Effective Action for Relativistic Superfluids
• The phases of isospin-asymmetric matter in the two-flavor NJL model
• Optimization of the derivative expansion in the nonperturbative renormalization group
• QCD at Finite Isospin Density
• Pion condensation in electrically neutral cold matter with finite baryon density
• Electrical neutrality and pion modes in the two flavor Polyakov–Nambu–Jona-Lasinio model