We study the chiral phase transition inside a rotating cylinder within the framework of the Namb--Jona-Lasinio model. A spectral boundary condition is imposed to avoid faster than light. We investigate how the geometry of the cylinder and rotation influence the chiral phase transition at finite temperature and chemical potential. The inhomogeneous effects caused by the finite size and rotation are also taken into account. It is found that finite size will reduce the chiral transition temperature and raises the chiral transition chemical potential, while the rotation reduces both the chiral transition temperature and chemical potential. In addition, we discuss the implications of our results in heavy-ion collisions and equation of states of neutron star.
We estimate the axion properties i.e. its mass, topological susceptibility and the self-coupling within the framework of Polyakov loop enhanced Nambu-Jona-Lasinio (PNJL) model at finite temperature and quark chemical potential. PNJL model, where quarks couple simultaneously to the chiral condensate and to a background temporal quantum chromodynamics (QCD) gauge field, includes two important features of QCD phase transition, i.e. deconfinement and chiral symmetry restoration. The Polyakov loop in PNJL model plays an important role near the critical temperature. We have shown significant difference in the axion properties calculated in PNJL model compared to the same obtained using Nambu-Jona-Lasinio (NJL) model. We find that both the mass of the axion and its self-coupling are correlated with the chiral transition as well as the confinement-deconfinement transition. We have also estimated the axion properties at finite chemical potential. Across the QCD transition temperature and/or quark chemical potential axion mass and its self-coupling also changes significantly. Since the PNJL model includes both the fermionic sector and the gauge fields, it can give reliable estimates of the axion properties, i.e. its mass and the self-coupling in a hot and dense QCD medium. We also compare our results with the lattice QCD results whenever available.
The effects of meson fluctuations are studied in a nonlocal generalization of the Nambu-Jona-Lasinio model, by including terms of next-to-leading order (NLO) in 1/N_c. In the model with only scalar and pseudoscalar interactions NLO contributions to the quark condensate are found to be very small. This is a result of cancellation between virtual mesons and Fock terms, which occurs for the parameter sets of most interest. In the quark self-energy, similar cancellations arise in the tadpole diagrams, although not in other NLO pieces which contribute at the sim 25% level. The effects on pion properties are also found to be small. NLO contributions from real $pipi$ intermediate states increase the sigma meson mass by $sim 30%$. In an extended model with vector and axial interactions, there are indications that NLO effects could be larger.
Effect of magnetic field on chiral symmetry breaking in a 3-flavor Nambu Jona Lasinio (NJL) model at finite temperature and densities is considered here using an explicit structure of ground state in terms of quark and antiquark condensates. While at zero chemical potential and finite temperature, magnetic field enhances the condensates, at zero temperature, the critical chemical potential decreases with increasing magnetic field.
We investigate the structure of protoneutron stars (PNS) formed by hadronic and quark matter in $beta$-equilibrium described by appropriate equations of state (EOS). For the hadronic matter, we use a finite temperature EOS based on the Brueckner-Bethe-Goldstone many-body theory, with realistic two- and three-body forces. For the quark sector, we employ the Nambu--Jona-Lasinio model. We find that the maximum allowed masses are comprised in a narrow range around 1.8 solar masses, with a slight dependence on the temperature. Metastable hybrid protoneutron stars are not found.
We study the solutions of the gap equation, the thermodynamic potential and the chiral susceptibility in and beyond the chiral limit at finite chemical potential in the Nambu--Jona-Lasinio (NJL) model. We give an explicit relation between the chiral susceptibility and the thermodynamic potential in the NJL model. We find that the chiral susceptibility is a quantity being able to represent the furcation of the solutions of the gap equation and the concavo-convexity of the thermodynamic potential in NJL model. It indicates that the chiral susceptibility can identify the stable state and the possibility of the chiral phase transition in NJL model.
Zheng Zhang
,Chao Shi
,Xiao-Tao He
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(2020)
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"Chiral phase transition inside a rotating cylinder within the Nambu--Jona-Lasinio model"
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Hong-Shi Zong
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