Abstract
AbstractIn this article, we study the two-flavor Nambu and Jona-Lasinio (NJL) phase diagrams on the T–μ plane through three regularization methods. In one of these, we introduce an infrared three-momentum cutoff in addition to the usual ultraviolet regularization to the quark loop integrals and compare the obtained phase diagrams with those obtained from the NJL model with proper time regularization and Pauli–Villars regularization. We have found that the crossover appears as a band with a well-defined width in the T–μ plane. To determine the extension of the crossover zone, we propose a novel criterion, comparing it to another criterion that is commonly reported in the literature; we then obtain the phase diagrams for each criterion. We study the behavior of the phase diagrams under all these schemes, focusing on the influence of the regularization procedure on the crossover zone and the presence or absence of critical end points.
Highlights
Quantum chromodynamics (QCD) is the theory that describes the strong interactions between quarks and gluons [1,2]
We propose a novel criterion for the determination of the width of the crossover zone, based on the value of the order parameter, and compare it to another criterion based on the behavior of the chiral susceptibility
The Nambu and Jona-Lasinio (NJL) model is very sensitive to the setting parameters [29], with the differences in the m0 value we can notice that the regularization procedure has a bigger impact in the phase diagrams than the parameters used
Summary
Quantum chromodynamics (QCD) is the theory that describes the strong interactions between quarks and gluons [1,2]. In the regime of low energies, the usual perturbative techniques applied in quantum field theory (QFT) cannot be used [3] because the coupling constant of QCD becomes large and running. Quarks are not any more the correct degrees of freedom in this regime of energies. Three of the main characteristics of QCD are the confinement, the asymptotic freedom and the spontaneous breaking of chiral symmetry at low energies [4,5]. Due to asymptotic properties, when a system of hadrons is subject to very high density, we expect to find the quarks in a free state, occupying a relatively large region
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