Narrow Results

The transfer matrix method to describe finite size effects due to tunneling are worked out for Z(2)- and Z(3)-symmetric models. We used this method to extract the surface tension σ in the SU(3) gauge theory at the finite temperature phase transition on lattices with an extent T=2 in the euclidean time direction. We also discuss if the confined phase completely wets the deconfined phase at this first order phase transition.

We critically review the cosmological EW and QCD phase transitions. The EW and QCD phase transitions would have proceeded dynamically since the expansion of the universe determines the quench rate and critical behaviors at the onset of phase transition slow down the phase transition. We introduce a real-time quench model for dynamical phase transitions and describe the evolution using a canonical real-time formalism. We find the correlation function, the correlation length and time and then discuss the cosmological implications of dynamical phase transitions on EW and QCD phase transitions in the early universe.

In this paper, we use the self-consistent mean field approximation to study the Quantum Chromodynamics (QCD) phase transition. In the self-consistent mean field approximation of the Nambu–Jona-Lasinio (NJL) model, a parameter $\alpha$ is introduced, which reflects the weight of “direct” channel and the “exchange” channel and needs to be determined by experiments (as mentioned in a recent work [T. Zhao, W. Zheng, F. Wang, C.-M. Li, Y. Yan, Y.-F. Huang and H.-S. Zong, Phys. Rev. D100, 043018 (2019)], the results with $\alpha =0.9$ are in good agreement with astronomical observation data on the latest binary neutron star merging. This indicates that the contribution of “exchange” channel should be considered, and $\alpha =0.9$ is a possible choice). By comparing the results with different parameter $\alpha$’s ($\alpha =0$, $\alpha =0.5$ and $\alpha =0.9$), we study the influence of “exchange” channel on the behavior of the solutions of the quark gap equation and the critical point of chiral phase transition. Our results show that the second-order chiral phase turns to the crossover from the chiral limit to the non-chiral limit around $\mu =360\mathrm{\text{MeV}}$ in the case of $\alpha =0.9$. The difference of the quark mass with different $\alpha$’s mainly occurs in the intermediate temperatures for the different fixed chemical potentials. At zero temperature and the chemical potential $\mu =334\mathrm{\text{MeV}}$ there will be two solutions (including a meta-stable solution) of gap equation with $\alpha =0$, and as $\alpha$ increases it will be only one solution left (the meta-stable solution will disappear until $\alpha =0.5$). Besides, the discrepancy of the critical temperature (above which the pseudo-Wigner solution and negative Nambu solution will disappear) in the three cases of $\alpha =0,0.5,0.9$ will become large when the chemical potential increases.

Color confinement is studied in dual version of SU(2) color gauge theory using its topological structure and the dynamical breaking of the magnetic symmetry which has been shown to effectively trigger the QCD monopole condensation in a dynamical way. The resulting flux tube structure of the QCD vacuum is explored which has been shown to lead to the perfect dual superconducting nature to the QCD vacuum in its dynamically broken phase. The analysis of the flux tube energy at different hadronic length scales has been shown to lead to the appearance of the strong confinement forces in QCD vacuum at large hadronic distances and an indication for the deconfinement phase at small scales. The analysis of the flux tube energy is then used to compute numerically the critical radius and the critical flux tube density of the phase transition from the flux tube phase to deconfined one inside hadrons. The numerical estimates are shown to be in fairly good agreement with the analytical values. The possible implications of these critical parameters on the formation of QGP as a result of the flux tubes fusion in intermediate energy regime are also discussed.

In the framework of rainbow approximation of the Dyson–Schwinger equation approach, it is shown that there exist two qualitatively distinct solutions of the Dyson–Schwinger equation for the quark propagator in the case of nonzero current quark mass. One solution corresponds to the "Nambu–Goldstone" phase and the other one corresponds to the "Wigner" phase in the chiral limit.

It is entirely plausible under reasonable conditions, that a first-order QCD phase transition occurred from quarks to hadrons when the universe was about a microsecond old. Relics, if there be any, after the quark–hadron phase transition are the most deciding signatures of the phase transition. It is shown in this paper that quark nuggets, the possible relics of first-order QCD phase transitions with baryon number larger than 10⁴³ will survive the entire history of the universe up to now and can be considered as a candidate for the cold dark matter. The spin down core of the neutron star on the high density low temperature end of the QCD phase diagram initiates transition from hadrons to quarks. As the star spins down, the size of the core goes on increasing. Recently discovered massive Pulsar PSRJ 1614-2230 with a mass of 1.97 ± 0.04M_⊙ most likely has a strongly interacting core. What possible observables can there be from these neutron stars?

This is a review of the Quantum Chromodynamics Cosmological Phase Transitions, the quark–gluon plasma, the production of heavy quark states via $p$–$p$ collisions and Relativistic Heavy Ion Collisions (RHIC) using the mixed hybrid theory for the $\mathrm{\Psi }(2S)$ and $\mathrm{{\rm Y}}(3S)$ states; and the possible detection of the quark–gluon plasma via heavy quark production using RHIC. Recent research on fragmentation for the production of $D$ mesons is reviewed, as is future theoretical and experimental research on the Collins and Sivers fragmentation functions for pions produced in polarized $p$–$p$ collisions.

This review of the quantum chromodynamics (QCD), the early universe cosmological phase transition from the quark–gluon plasma (QGP) to our present universe (QCDPT), relativistic heavy ion collisions (RHIC) which can produce the QGP, the possible detection of the QGP produced by the production of mixed hybrid heavy quark mesons. We also review the recent studies of the production of mixed heavy quark hybrids via RHIC and heavy quark meson suppression in p-Pb and Pb–Pb collisions.

In this proceedings contribution we discuss the fate of the electroweak and the quantum chromodynamics phase transitions relevant for the early stage of the universe at non-zero temperature. These phase transitions are related to the Higgs mechanism and the breaking of chiral symmetry, respectively. We will review that non-perturbative lattice field theory simulations show that these phase transitions actually do not occur in nature and that physical observables show a completely smooth behaviour as a function of the temperature.

It is proposed that the $O(n)$ spin and geometrical percolation models can help to study the QCD phase diagram due to the universality properties of the phase transition. In this paper, correlations and fluctuations of various sizes of cluster in the Ising model are systematically studied. With a finite size system, we demonstrate how to use the finite size scaling and fixed point behavior to search for critical point. At critical point, the independency of system size is found from skewness and kurtosis of the maximum, second and third largest cluster and their correlations. It is similar to the Binder-ratio, which has provided a remarkable identification of the critical point. Through an explanation of the universal characteristic of skewness and kurtosis of the order parameter, a possible application to the relativistic heavy-ion collisions is also discussed.

In this paper, we use the two-flavor Nambu–Jona-Lasinio model together with the proper time regularization that has both ultraviolet and infrared cutoffs to study the chiral phase transition at finite temperature and zero chemical potential. The involved model parameters in our calculation are determined in the traditional way. Our calculations show that the dependence of the results on the choice of the parameters are really small, which can then be regarded as an advantage besides such a regularization scheme is Lorentz invariant.

We perform hydrodynamical collapse and bounce simulations of neutron stars induced by QCD phase transition. We study how the phase transition affects the elements of the envelopes and crusts of neutron stars near the epoch of core-bounce. We assume the first-order phase transition, a chirally symmetric quark-gluon plasma for quark phase. The initial elements are adopted from the realistic evolutional calculations of neutron stars containing the cooling effects and the nucleosynthesis of envelope such as type I X-ray burst. We find that the elements of envelope can eject directly (without nucleosynthesis) for such a collapse and bounce by the transition.

We perform two-dimensional, magneto-hydrodynamical simulations of "petit" collapse and bounce of neutron stars by QCD phase transition. We study how the phase transition affects the elements of the ejecta near the epoch of core-bounce. We find that the elements of envelope can eject without nucleosynthesis for such a "petit" collapse and bounce by the transition. In addition, we estimate the gravitational wave using the quadrupole formula.

First-order phase transitions (PTs) with more than one globally conserved charge, so-called noncongruent PTs, have characteristic differences compared to congruent PTs (e.g., dimensionality of phase diagrams and location of critical points and endpoints). Here we discuss the noncongruent features of the QCD PT and compare it with the nuclear liquid-gas (LG) PT, for symmetric and asymmetric matter in heavy-ion collisions and neutron stars. In addition, we have identified a principle difference between the LG and the QCD PT: they have opposite slopes in the pressure-temperature plane.

We discuss characteristic properties of fluctuations of conserved charges expected for the phase boundary in QCD. Probability distribution of the net baryon number and its higher order cumulants are presented for chiral crossover transition in a chiral quark-meson model. Implication for the experimental data on net-proton fluctuation is also discussed.

Questions to discuss:

• Which experimental data (dis)prove deconfinement of the QCD matter created in heavy ion collisions?
• Which grounds are there for thermodynamics application to describe the QCD matter produced at RHIC and LHC energies?
• Which experimental data confirm existence or absence of phase transition in heavy ion collisions?
• Which new properties of quark-gluon matter are observed at LHC compared with those at RHIC and which are plans for the future?
• Is there any evolution in our understanding of the QCD matter from RHIC to LHC energies?