arXiv subjects

Wei-jie Fu

Publications and source records attributed to Wei-jie Fu.

65 records · Page 4Linked to original sources

arXiv2015

On the relevance of matter and glue dynamics for baryon number fluctuations

We investigate the impact of the matter and glue dynamics on baryon number fluctuations and the kurtosis of baryon number distribution. This is done within the framework of QCD-improved low energy effective models. In particular we include the momentum scale dependence of the quark-meson scattering and the non-trivial dispersions of both, quarks and mesons. On the gluonic side we take into account the backreaction of the matter sector on the glue dynamics. It is shown that the above fluctuations lead to a more rapid change of the baryon number fluctuations as well as the kurtosis of with the chiral crossover. We also study the signatures of quark confinement in low energy QCD. It is shown that contrary to the common picture the effective thermal distribution in the presence of confining glue backgrounds does not tend towards the colourless baryonic one. Instead, the dominance of colourless hadronic states is obtained in a subtle interplay of quark and glue contributions to the canonical potential.

hep-ph↗

arXiv2013

Fluctuations and correlations of hot QCD matter in an external magnetic field

Effects of an external magnetic field on the fluctuations of quark number, fluctuations and correlations of conserved charges, including baryon number, electric charge and strangeness, are studied in the 2+1 flavor Polyakov--Nambu--Jona-Lasinio model. We find that magnetic field increases fluctuations and correlations in the regime of chiral crossover. It makes the transition of quadratic fluctuations more abrupt, and the peak structure of quartic fluctuations more pronounced. Our calculations indicate that $χ_{4}^{B}/χ_{2}^{B}$, $χ_{4}^{Q}/χ_{2}^{Q}$, and $χ_{11}^{BQ}$ are very sensitive to the external magnetic field and maybe can be used for probes for the strong magnetic field produced in the early stage of noncentral collisions.

hep-ph↗

arXiv2010

Time-dependent Ginzburg-Landau Equation in the Nambu--Jona-Lasinio Model

We apply the closed time-path Green function formalism in the Nambu--Jona-Lasinio model. First of all, we use this formalism to obtain the well-known gap equation for the quark condensate in a stationary homogeneous system. We have also used this formalism to obtain the Ginzburg-Landau (GL) equation and the time-dependent Ginzburg-Landau (TDGL) equation for the chiral order parameter in an inhomogeneous system. In our derived GL and TDGL equations, there is no other parameters except for those in the original NJL model.

hep-ph↗

arXiv2010

Fourth-order Correlations of Conserved Charges in the QCD Thermodynamics

The fourth-order correlations of conserved charges, such as the baryon number, electric charge, and strangeness, are studied at finite temperature and nonzero baryon chemical potential in an effective model. It is found that the fourth-order correlations change rapidly and have three extrema during the chiral crossover with the increase of the baryon chemical potential. The absolute values of the extrema approach infinity when the thermodynamical system moves toward the QCD critical point and the fourth-order correlations are divergent at the critical point. The contour plots of the fourth-order correlations in the plane of the temperature and baryon chemical potential are given. It is noticed that all the fourth-order correlations of conserved charges, except for $χ_{13}^{BS}$ and $χ_{13}^{QS}$, are excellent probes to explore the QCD critical point in heavy ion collision experiments.

hep-ph↗

arXiv2010

Fluctuations and Correlations of Conserved Charges near the QCD Critical Point

We study the fluctuations and correlations of conserved charges, i.e. the baryon number, electric charge and the strangeness at finite temperature and nonzero baryon chemical potential with an effective model. The fluctuations are calculated up to the fourth-order and the correlations to the third-order. We find that the second-order fluctuations and correlations have a peak or valley structure when the chiral phase transition takes place with the increase of the baryon chemical potential; the third-order fluctuations and correlations change their signs during the chiral phase transition and the fourth-order fluctuations have two maximum and one minimum. we also depict contour plots of various fluctuations and correlations of conserved charges in the plane of temperature and baryon chemical potential. We find that higher order fluctuations and correlations of conserved charges are superior to the second-order ones to be used to search for the critical point in heavy ion collision experiments.

hep-ph↗

arXiv2010

Chiral Magnetic Effect and QCD Phase Transitions with Effective Models

We study the influence of the chiral phase transition on the chiral magnetic effect. The chiral electric current density along the magnetic field, the electric charge difference between on each side of the reaction plane, and the azimuthal charged-particle correlations as functions of the temperature during the QCD phase transitions are calculated. It is found that with the decrease of the temperature, the chiral electric current density, the electric charge difference, and the azimuthal charged-particle correlations all get a sudden suppression at the critical temperature of the chiral phase transition, because the large quark constituent mass in the chiral symmetry broken phase quite suppresses the axial anomaly and the chiral magnetic effect. We suggest that the azimuthal charged-particle correlations (including the correlators divided by the total multiplicity of produced charged particles which are used in current experiments and another kind of correlators not divided by the total multiplicity) can be employed to identify the occurrence of the QCD phase transitions in RHIC energy scan experiments.

hep-ph↗

arXiv2010

Fluctuations and Correlations of Conserved Charges in QCD at Finite Temperature with Effective Models

We study fluctuations of conserved charges including baryon number, electric charge, and strangeness as well as the correlations among these conserved charges in the 2+1 flavor Polyakov--Nambu--Jona-Lasinio model at finite temperature. The calculated results are compared with those obtained from recent lattice calculations performed with an improved staggered fermion action at two values of the lattice cutoff with almost physical up and down quark masses and a physical value for the strange quark mass. We find that our calculated results are well consistent with those obtained in lattice calculations except for some quantitative differences for fluctuations related with strange quarks. Our calculations indicate that there is a pronounced cusp in the ratio of the quartic to quadratic fluctuations of baryon number, i.e. $χ_{4}^{B}/χ_{2}^{B}$, at the critical temperature during the phase transition, which confirms that $χ_{4}^{B}/χ_{2}^{B}$ is a useful probe of the deconfinement and chiral phase transition.

hep-ph↗

arXiv2010

Chiral Magnetic Effect and Chiral Phase Transition

We study the influence of the chiral phase transition on the chiral magnetic effect. The azimuthal charge-particle correlations as functions of the temperature are calculated. It is found that there is a pronounced cusp in the correlations as the temperature reaches its critical value for the QCD phase transition. It is predicted that there will be a drastic suppression of the charge-particle correlations as the collision energy in RHIC decreases to below a critical value. We show then the azimuthal charge-particle correlations can be the signal to identify the occurrence of the QCD phase transitions in RHIC energy scan experiments.

hep-ph↗

arXiv2009

Mesonic excitations and pi--pi scattering lengths at finite temperature in the two-flavor Polyakov--Nambu--Jona-Lasinio model

The mesonic excitations and s-wave pi--pi scattering lengths at finite temperature are studied in the two-flavor Polyakov--Nambu--Jona-Lasinio (PNJL) model. The masses of pi-meson and sigma-meson, pion-decay constant, the pion-quark coupling strength, and the scattering lengths $a_{0}$ and $a_{2}$ at finite temperature are calculated in the PNJL model with two forms of Polyakov-loop effective potential. The obtained results are almost independent of the choice of the effective potentials. The calculated results in the PNJL model are also compared with those in the conventional Nambu--Jona-Lasinio model and indicate that the effect of color confinement screens the effect of temperature below the critical one in the PNJL model. Furthermore, the Goldberger-Treiman relation and the Gell-Mann--Oakes--Renner relation are extended to the case at finite temperature in the PNJL model.

hep-ph↗

arXiv2008

Distinguishing Newly Born Strange Stars from Neutron Stars with g-Mode Oscillations

The gravity-mode (g-mode) eigenfrequencies of newly born strange quark stars (SQSs) and neutron stars (NSs) are studied. It is found that the eigenfrequencies in SQSs are much lower than those in NSs by almost one order of magnitude, since the components of a SQS are all extremely relativistic particles while nucleons in a NS are non-relativistic. We therefore propose that newly born SQSs can be distinguished from the NSs by detecting the eigenfrequencies of the g-mode pulsations of supernovae cores through gravitational radiation by LIGO-class detectors.

nucl-th↗

arXiv2007

2+1 Flavor Polyakov--Nambu--Jona-Lasinio Model at Finite Temperature and Nonzero Chemical Potential

We extend the Polyakov-loop improved Nambu--Jona-Lasinio (PNJL) model to 2+1 flavor case to study the chiral and deconfinement transitions of strongly interacting matter at finite temperature and nonzero chemical potential. The Polyakov-loop, the chiral susceptibility of light quarks (u and d) and the strange quark number susceptibility as functions of temperature at zero chemical potential are determined and compared with the recent results of Lattice QCD simulations. We find that there is always an inflection point in the curve of strange quark number susceptibility accompanying the appearance of the deconfinement phase, which is consistent with the result of Lattice QCD simulations. Predictions for the case at nonzero chemical potential and finite temperature are made as well. We give the phase diagram in terms of the chemical potential and temperature and find that the critical endpoint (CEP) moves down to low temperature and finally disappears with the decrease of the strength of the 't Hooft flavor-mixing interaction.

hep-ph↗