Evaluating the phase diagram at finite isospin and baryon chemical potentials in the Nambu-Jona-Lasinio model

Journal Article · Wed Sep 01 00:00:00 EDT 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.82.056006· OSTI ID:21421085

Chengfu, Mu ^[1]; Lianyi, He ^[2]; Yuxin, Liu ^[1]

---

1. Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China)
2. Frankfurt Institute for Advanced Studies and Institute for Theoretical Physics, J.W. Goethe University, 60438 Frankfurt am Main (Germany)

We study the phase diagram of two-flavor dense QCD at finite isospin and baryon chemical potentials in the framework of the Nambu-Jona-Lasinio model. We focus on the case with arbitrary isospin chemical potential {mu}{sub I} and small baryon chemical potential {mu}{sub B{<=}{mu}B}{sup {chi}}where {mu}{sub B}{sup {chi}}is the critical chemical potential for the first-order chiral phase transition to happen at {mu}{sub I}=0. The {mu}{sub I}-{mu}{sub B} phase diagram shows a rich phase structure since the system undergoes a crossover from a Bose-Einstein condensate of charged pions to a BCS superfluid with condensed quark-antiquark Cooper pairs when {mu}{sub I} increases at {mu}{sub B}=0, and a nonzero baryon chemical potential serves as a mismatch between the pairing species. We observe a gapless pion condensation phase near the quadruple point ({mu}{sub I},{mu}{sub B})=(m{sub {pi}},M{sub N}-1.5m{sub {pi}}) where m{sub {pi}}, M{sub N} are the vacuum masses of pions and nucleons, respectively. The first-order chiral phase transition becomes a smooth crossover when {mu}{sub I}>0.82m{sub {pi}}. At very large isospin chemical potential, {mu}{sub I}>6.36m{sub {pi}}, an inhomogeneous Larkin-Ovchinnikov-Fulde-Ferrell superfluid phase, appears in a window of {mu}{sub B}, which should in principle exist for arbitrary large {mu}{sub I}. Between the gapless and the Larkin-Ovchinnikov-Fulde-Ferrell phases, the pion superfluid phase and the normal quark matter phase are connected by a first-order phase transition. In the normal phase above the superfluid domain, we find that charged pions are still bound states even though {mu}{sub I} becomes very large, which is quite different from that at finite temperature. Our phase diagram is in good agreement with that found in imbalanced cold atom systems.

• OSTI ID: 21421085
• Journal Information: Physical Review. D, Particles Fields, Vol. 82, Issue 5; Other Information: DOI: 10.1103/PhysRevD.82.056006; (c) 2010 American Institute of Physics; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ATOMS
BOSE-EINSTEIN CONDENSATION
BOUND STATE
CHIRALITY
COOPER PAIRS
FLAVOR MODEL
ISOSPIN
MASS
NUCLEONS
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
PION CONDENSATION
PIONS
QUANTUM CHROMODYNAMICS
QUARK MATTER
QUARK-ANTIQUARK INTERACTIONS
SIMULATION
SUPERFLUIDITY
BARYONS
BOSONS
COMPOSITE MODELS
DIAGRAMS
ELEMENTARY PARTICLES
FERMIONS
FIELD THEORIES
HADRONS
INFORMATION
INTERACTIONS
MATHEMATICAL MODELS
MATTER
MESONS
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE PROPERTIES
PSEUDOSCALAR MESONS
QUANTUM FIELD THEORY
QUARK MODEL