Chiral condensate of cold dense quark matter with external magnetic field

2020 ◽  
Vol 35 (19) ◽  
pp. 2050160
Author(s):  
Song Shi ◽  
Juan Liu
Keyword(s):  
Magnetic Field ◽  
Phase Diagram ◽  
External Magnetic Field ◽  
Quark Matter ◽  
Chemical Potential ◽  
Field Approximation ◽  
Chiral Condensate ◽  
Mean Field Approximation ◽  
Dynamical Mass ◽  
Dense Quark Matter

At zero temperature and finite chemical potential, the gap equation of cold dense quark matter under external magnetic field is studied with NJL model in the mean-field approximation. By introducing new methods, it is found that the Nambu phase has sophisticated structures which have not been studied before. As a consequence, the phase diagram is expanded and divided into five areas, in each area the condensate has unique behaviors with chemical potential varying. Furthermore, the expanded phase diagram is used to predict the order of phase transition between the Nambu phase and the Wigner phase, it can also be used to explain the relations of dynamical mass and chemical potential. Meanwhile, the metastable states and cascade effect of dynamical mass are studied in this paper.

scholarly journals Inhomogeneous chiral condensates in low-energy color-superconductivity models of QCD

2021 ◽  
Author(s):  
◽  
Philip Lakaschus
Keyword(s):  
Phase Diagram ◽  
Mean Field ◽  
Field Approximation ◽  
Chiral Condensate ◽  
Dispersion Relations ◽  
Mean Field Approximation ◽  
Color Superconductivity ◽  
Diquark Model ◽  
Coexistence Phase ◽  
The Mean

This thesis explores the phase diagrams of the Nambu--Jona-Lasinio (NJL) and quark-meson (QM) model in the mean-field approximation and beyond. The focus lies in the investigation of the interplay between inhomogeneous chiral condensates and two-flavor color superconductivity. In the first part of this thesis, we study the NJL model with 2SC diquarks in the mean-field approximation and determine the dispersion relations for quasiparticle excitations for generic spatial modulations of the chiral condensate in the presence of a homogeneous 2SC-diquark condensate, provided that the dispersion relations in the absence of color superconductivity are known. We then compare two different Ansätze for the chiral order parameter, the chiral density wave (CDW) and the real-kink crystal (RKC). For both Ansätze we find for specific diquark couplings a so-called coexistence phase where both the inhomogeneous chiral condensate and the diquark condensate coexist. Increasing the diquark coupling disfavors the coexistence phase in favor of a pure diquark phase. On the other hand, decreasing the diquark coupling favors the inhomogeneous phase over the coexistence phase. In the second part of this thesis the functional renormalization group is employed to study the phase diagram of the quark-meson-diquark model. We observe that the region of the phase diagram found in previous studies, where the entropy density takes on unphysical negative values, vanishes when including diquark degrees of freedom. Furthermore, we perform a stability analysis of the homogeneous phase and compare the results with those of previous studies. We find that an increasing diquark coupling leads to a smaller region of instability as the 2SC phase extends to a smaller chemical potential. We also find a region where simultaneously an instability occurs and a non-vanishing diquark condensate forms, which is an indication of the existence of a coexistence phase in accordance with the results of the first part of this work.

scholarly journals Non-Hermitian BCS-BEC crossover of Dirac fermions

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Takuya Kanazawa
Keyword(s):  
Chiral Symmetry ◽  
Chemical Potential ◽  
Chiral Symmetry Breaking ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Dirac Fermions ◽  
Coupling Constant ◽  
Dynamical Mass ◽  
The Mean

Abstract We investigate chiral symmetry breaking in a model of Dirac fermions with a complexified coupling constant whose imaginary part represents dissipation. We introduce a chiral chemical potential and observe that for real coupling a relativistic BCS-BEC crossover is realized. We solve the model in the mean-field approximation and construct the phase diagram as a function of the complex coupling. It is found that the dynamical mass increases under dissipation, although the chiral symmetry gets restored if dissipation exceeds a threshold.

scholarly journals Revisiting quark stars under the influence of strong magnetic fields

2012 ◽  
Vol 8 (S291) ◽  
pp. 458-458
Author(s):  
Debora Menezes
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Quark Matter ◽  
Mean Field ◽  
Heavy Ion ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Solar Mass ◽  
Strong Magnetic Fields ◽  
The Masses

AbstractQuark matter at finite temperature and subject to strong magnetic fields is possibly present in the early stages of heavy ion collisions and in the interior of protoneutron stars. We use the mean field approximation to investigate this type of quark matter described by the Nambu–Jona-Lasinio model. The energy per baryon of magnetized quark matter becomes more bound than nuclear matter made of iron nuclei, for magnetic fields around 1019 G. When the su(3) NJL model is applied to stellar matter, the maximum mass configurations are always above 1.45 solar masses and may be as high as 1.9 solar masses for a central magnetic field of 1018 G. These numbers are within the masses of observed neutron stars but exclude the recently measured star with 1.97 solar mass.The effect of the magnetic field on the effective quark masses and chemical potentials is only felt for quite strong magnetic fields, above 5 × 1018 G, with larger effects for the lower densities. Spin polarizations are more sensitive to weaker magnetic fields and are larger for lower temperatures and lower densities.

scholarly journals PHASE DIAGRAM OF TWO-FLAVOR QUARK MATTER: GLUONIC PHASE AT NONZERO TEMPERATURE

2009 ◽  
Vol 24 (09) ◽  
pp. 647-658
Author(s):  
O. KIRIYAMA
Keyword(s):  
Phase Diagram ◽  
Quark Matter ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Nonzero Temperature ◽  
Self Consistent ◽  
Consistent Manner ◽  
Cylindrical Phase ◽  
The Mean

The phase structure of neutral two-flavor quark matter at nonzero temperature is studied. Our analysis is performed within the framework of a gauged Nambu–Jona-Lasinio model and the mean-field approximation. We compute the free energy of the gluonic phase (gluonic cylindrical phase II) in a self-consistent manner and investigate the phase transition from the gluonic phase to the 2SC/g2SC/NQ phases. We briefly consider the phase diagram in the plane of coupling strength versus temperature and discuss the mixed phase consisting of the normal quark and 2SC phases.

QCD susceptibilities in the presence of the chiral chemical potential

2020 ◽  
Vol 35 (16) ◽  
pp. 2050137
Author(s):  
Run-Lin Liu ◽  
Hong-Shi Zong
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Chemical Potential ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Chiral Phase ◽  
First Order Phase Transition ◽  
Phase Transition Region ◽  
First Order Phase

In this paper, chiral chemical potential [Formula: see text] is introduced to investigate the QCD susceptibilities and chiral phase transition within the Polyakov-loop-extended Nambu–Jona-Lasinio models in the mean-field approximation. We concentrate on the effect of chiral chemical potential on the phase diagram and the QCD susceptibilities. Moreover, it is worth noting that chiral chemical potential has more and more prominent impact on the susceptibilities and the phase diagram with the decrease of temperature based on our results, which coincides with the prediction that the chiral symmetry is dynamically broken in the first-order phase transition region and gets partly restored in the crossover region.

Critical Behaviour of the Ferromagnetic Spin-3/2 – Blume-Emery-Griffiths Model with Repulsive Biquadratic Coupling

2007 ◽  
Vol 62 (3-4) ◽  
pp. 127-139 ◽  
Author(s):  
M. Ali Pınar ◽  
Mustafa Keskin ◽  
Ahmet Erdinç ◽  
Osman Canko
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Phase Diagrams ◽  
Mean Field ◽  
Cluster Variation Method ◽  
Field Approximation ◽  
Critical Behaviour ◽  
Mean Field Approximation ◽  
Variation Method ◽  
Cluster Variation

The critical behaviour of the ferromagnetic spin-3/2 Blume-Emery-Griffiths model with repulsive biquadratic coupling in the absence and presence of an external magnetic field is studied by using the lowest approximation of the cluster variation method, which is identical with the mean-field approximation. Thermal variations of the order parameters are investigated for different values of the interaction parameters and the external magnetic field. The complete phase diagrams of the system are calculated in the (kT/J,K/J), (kT/J,D/J) and (kT /J,H/J) planes. Five new phase diagram topologies are obtained, which are either absent from previous approaches or have gone unnoticed. A detailed discussion and comparison of the phase diagrams is made.

scholarly journals PHASE DIAGRAM OF ADSORBATE-INDUCED ROW-TYPE ALIGNMENTS

1999 ◽  
Vol 06 (05) ◽  
pp. 691-697 ◽  
Author(s):  
M. KANG ◽  
K. YASUTANI ◽  
M. KABURAGI
Keyword(s):  
Phase Diagram ◽  
High Temperatures ◽  
Nearest Neighbor ◽  
Chemical Potential ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Dipole Interactions ◽  
Beg Model ◽  
Incommensurate Phases

The phase diagram of adsorbate-induced row-type alignments, such as missing-row reconstructions induced by adsorbate atoms on the FCC(110) surface, is calculated by the Blume–Emmery–Griffiths (BEG) model. In the model, we introduce adatom–adatom and dipole–dipole interactions between nearest-neighbor (NN) and next-nearest-neighbor (NNN) rows. The calculation of the temperature versus adatom chemical potential phase diagram is performed using mean-field approximation. It is indicated that when NN and NNN interactions are competitive, there appear either dipole or coverage modulated (incommensurate) phases at high temperatures for a wide regime of the interactions.

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