Hong-Shi Zong

Nanjing University, Nan-ching, Jiangsu Sheng, China

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Publications (133)413.22 Total impact

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    Ya Lu · Yi-Lun Du · Zhu-Fang Cui · Hong-Shi Zong
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    ABSTRACT: We investigate the dynamical chiral symmetry breaking and its restoration at finite density and temperature within the two-flavor Nambu-Jona-Lasinio model, and mainly focus on the critical behaviors near the critical end point (CEP) and tricritical point (TCP) of QCD. The co-existence region of the Wigner and Nambu phase is determined in the phase diagram for the massive and massless current quark, respectively. We use the various susceptibilities to locate the CEP/TCP and then extract the critical exponents near them. Our calculations reveal that the various susceptibilities share the same critical behaviors for the physical current quark mass, while they show different features in the chiral limit. Furthermore the critical exponent of order parameter at the TCP, $\beta$=1/4, differs from that on the $O(4)$ line, $\beta$=1/2, which indicates a change in the universality class.
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    Shu-Sheng Xu · Yan Yan · Zhu-Fang Cui · Hong-Shi Zong
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    ABSTRACT: Within the framework of Dyson-Schwinger equations (DSEs), we discuss the equation of state (EOS) and quark number densities of 2+1 flavors, that is to say, $u$, $d$, and $s$ quarks. The chemical equilibrium and electric charge neutrality conditions are used to constrain the chemical potential of different quarks. The EOS in the cases of 2 flavors and 2+1 flavors are discussed, and the quark number densities, the pressure, and energy density per baryon are also studied. The results show that there is a critical chemical potential for each flavor of quark, at which the quark number density turns to nonzero from 0; and furthermore, the system with 2+1 flavors of quarks is more stable than that with 2 flavors in the system. These discussion may provide some useful information to some research fields, such as the studies related to the QCD phase transitions or compact stars.
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    Yi-Lun Du · Ya Lu · Shu-Sheng Xu · Zhu-Fang Cui · Chao Shi · Hong-Shi Zong
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    ABSTRACT: In the mean field approximation of (2+1)-flavor Nambu--Jona-Lasinio model, we strictly derive several sets of coupled equations for the chiral susceptibility, the quark number susceptibility, etc. at finite temperature and quark chemical potential. The critical exponents of these susceptibilities in the vicinity of the QCD critical end point (CEP) are presented in SU(2) and SU(3) cases, respectively. It is found that these various susceptibilities share almost the same critical behavior near the CEP. The comparisons between the critical exponents for the order parameters and the theoretical predictions are also included.
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    ABSTRACT: Within the framework of Dyson-Schwinger equations (DSEs), we discuss the chiral phase transition of QCD with a chiral chemical potential $\mu_5$ as an additional scale. We focus especially on the issues related to the widely accepted as well as interested critical end point (CEP). With the help of a scalar susceptibility, we find that there might be no CEP$_5$ in the $T-\mu_5$ plane, and the phase transition in the $T-\mu_5$ plane might be totally crossover when $\mu<50$ MeV, which has apparent consistency with the Lattice QCD calculation. Our study may also provide some useful hints to some other studies related to $\mu_5$.
    Physical Review D 05/2015; 91(5). DOI:10.1103/PhysRevD.91.056003 · 4.86 Impact Factor
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    ABSTRACT: We employ a continuum approach to the three valence-quark bound-state problem in relativistic quantum field theory to predict a range of properties of the proton's radial excitation and thereby unify them with those of numerous other hadrons. Our analysis indicates that the nucleon's first radial excitation is the Roper resonance. It consists of a core of three dressed-quarks, which expresses its valence-quark content and whose charge radius is 80% larger than the proton analogue. That core is complemented by a meson cloud, which reduces the observed Roper mass by roughly 20%. The meson cloud materially affects long-wavelength characteristics of the Roper electroproduction amplitudes but the quark core is revealed to probes with $Q^2 \gtrsim 3 m_N^2$.
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    ABSTRACT: The QCD vacuum condensates and various vacuum susceptibilities are all important parameters which characterize the nonperturbative properties of the QCD vacuum. In the QCD sum rules external field formula, various QCD vacuum susceptibilities play important roles in determining the properties of hadrons. In this paper, we review the recent progress in studies of vacuum susceptibilities together with their applications to the chiral phase transition of QCD. The results of the tensor, the vector, the axial-vector, the scalar, and the pseudo-scalar vacuum susceptibilities are shown in detail in the framework of Dyson-Schwinger equations.
    Annals of Physics 04/2015; 358. DOI:10.1016/j.aop.2015.03.025 · 3.07 Impact Factor
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    ABSTRACT: We compute all kaon and pion parton distribution amplitudes (PDAs) to twist-three and find that only the pseudotensor PDA can reasonably be approximated by its conformal limit expression. At terrestrially accessible energy scales, the twist-two and pseudoscalar twist-three PDAs differ significantly from those functions commonly associated with their forms in QCD's conformal limit. In all amplitudes studied, SU(3) flavour-symmetry breaking is typically a 13% effect. This scale is determined by nonperturbative dynamics; namely, the current-quark-mass dependence of dynamical chiral symmetry breaking. The heavier-quark is favoured by this distortion, for example, support is shifted to the s-quark in the negative kaon. It appears, therefore, that at energy scales accessible with existing and foreseeable facilities, one may obtain reliable expectations for experimental outcomes by using these "strongly dressed" PDAs in formulae for hard exclusive processes. Following this procedure, any discrepancies between experiment and theory will be significantly smaller than those produced by using the conformal-limit PDAs. Moreover, the magnitude of any disagreement will either be a better estimate of higher-order, higher-twist effects or provide more realistic constraints on the Standard Model.
    Physical Review D 04/2015; 92(1). DOI:10.1103/PhysRevD.92.014035 · 4.86 Impact Factor
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    ABSTRACT: In this paper we develop a new method that is different from Schwinger proper time method to deduce the fermion propagator with a constant external magnetic field. In the NJL model, we use this method to find out the gap equation at zero and non-zero temperature, and give the numerical results and phase diagram between magnetic field and temperature. Beside these, we also introduce current mass to study the susceptibilities, because there is a new parameter (the strength of external magnetic field) in this problem, corresponding this new parameter, we have defined a new susceptibility $\chi_B$ to compare with the other two susceptibilities $\chi_c$ (chiral susceptibility) and $\chi_T$ (thermal susceptibility), and all of the three susceptibilities show than when current mass is not zero, the phase transition is a crossover, while for comparison, in the chiral limit, the susceptibilities show a second order phase transition. At last, we give out the critical coefficients of different susceptibilities in the chiral limit.
    Physical Review D 03/2015; 91(3). DOI:10.1103/PhysRevD.91.036006 · 4.86 Impact Factor
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    Yong-Long Wang · Hong-Shi Zong
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    ABSTRACT: We clearly refine a fundamental framework for the thin-layer quantization scheme. Further, we definitively clarify a performing sequence in the thin-layer quantization process. The limit $q_3\to 0$ ($q_3$ denotes the variable perpendicular to the curved surface) must be performed after calculating all curvilinear coordinate derivatives. In the general form, a canonical action integral, the limit $d\to 0$ ($d$ is the thickness of the curved surface) has to be calculated after performing all curvilinear coordinate integrations. In complete accordance with the sequence, in the presence of an electromagnetic field, for a charged particle constrained on a spatially curved surface the Lorentz gauge and the Schr\"{o}dinger equation cannot be decoupled from the mean curvature of the surface simultaneously, except $A^3=0$ ($A^3$ is a contravariant component along the direction perpendicular to the curved surface of the electromagnetic field vector potential $\vec{A}$) with a certain gauge transformation, and the canonical action integral does not show convenience for the thin-layer quantization scheme. Additionally, we derive the modifications induced by the thickness of the surface to the geometric potential and the kinetic operator.
  • Tong Zhao · Yan Yan · Xin-Lian Luo · Hong-Shi Zong
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    ABSTRACT: In this paper we utilize our improved quasiparticle model to obtain the equation of state (EOS) and use it as an input to the Tolman-Oppenheimer-Volkoff (TOV) equation to get the mass-radii relation of a pure quark star. We discuss the relation between structures of quark stars and the parameters in the EOS and get a maximum mass of quark star over two solar mass. To compare the result with recent observation, we also calculate the structure of a hybrid star and consider the influence of rotation. Finally, the hadron-quark phase transition in the interior of neutron stars and how much energy will be released when a neutron star bursts into a quark star are discussed.
    Physical Review D 02/2015; 91(3). DOI:10.1103/PhysRevD.91.034018 · 4.86 Impact Factor
  • Yu Jiang · Feng-Yao Hou · Cui-Bai Luo · Hong-Shi Zong
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    ABSTRACT: We calculate the quark number susceptibility (QNS) around the chiral critical end point (CEP). The CEP is found to be located at (μc, Tc) = (80 MeV, 148 MeV) where μc and Tc are the critical chemical potential and temperature, respectively. The QNS is found to have the highest and sharpest peak at the CEP. It is also found that, when the chemical potential μ is in the range of 60 MeV≤ μ ≤ 110 MeV, the QNS near the transition temperature is larger than the free field result, which indicates that the space-like damping mode dominates the degree of freedom of motion near the CEP.
    Chinese Physics Letters 02/2015; 32(2):021201. DOI:10.1088/0256-307X/32/2/021201 · 0.95 Impact Factor
  • Bin Wang · Yong-Long Wang · Zhu-Fang Cui · Hong-Shi Zong
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    ABSTRACT: The effect of chiral imbalance on the QCD phase structure is studied in a framework of Dyson\char21{}Schwinger equations. It is found that the chiral phase transition is always a crossover in the $T$-${}{$\mu${}}_{5}$ plane when $$\mu${}$ is 0 MeV or small values. The trail of the critical endpoints (CEPs) along with the variation of the chiral chemical potential is given. We find that the effect of ${$\mu${}}_{5}$ is somewhat different from the existing chiral model calculations; namely, the CEP first moves roughly along the phase boundary of $T$-${}$\mu${}$ plane in a smaller $$\mu${}$ direction, as in the chiral model calculations, but turns in the opposite direction to move away from the small chemical potential region, which has never been observed before. In addition, we also discuss the possibility of whether the study at finite temperature and chiral chemical potential can provide some useful information for the detection of the CEP at finite temperature and baryon chemical potential, since the former can be calculated in lattice QCD without the sign problem.
    Physical Review D 02/2015; 91(3). DOI:10.1103/PhysRevD.91.034017 · 4.86 Impact Factor
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    Wei Wei · Pei-lin Yin · Hong-shi Zong
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    ABSTRACT: The studies of Dyson-Schwinger Equations (DSEs) provide us with insights into nonperturbative phenomenon of quantum field theory. However, DSEs are essentially an infinite set of coupled Green's functions, it's necessary to decouple parts of the equations which are thought of major physical importance to make the solution of these equations possible. Although the results are model-dependent, no qualitative deviations from exact solutions are expected with properly chosen truncation scheme. In this article, a globally convergent numerical method for the solution of the DSEs of QED$_3$ in Euclidean space is presented. This method can be adapted for more complex problems, however, it also shows its limitations when adopted in problems such as the searching for Wigner solutions.
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    A-Meng Zhao · Zhu-Fang Cui · Yu Jiang · Hong-Shi Zong
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    ABSTRACT: Since the baryon-number susceptibilities are correlated with the cumulant of baryon-number fluctuations in experiments, we do calculations of the susceptibilities and compare them with the experimental fluctuation data under the framework of the Dyson-Schwinger equations (DSEs) approach. We compare our results with lattice QCD and experimental data at RHIC. The fitness of the results indicates that under the framework of DSEs, we can deal with the problems of heavy ion collisions properly.
    Physical Review D 12/2014; 90(11). DOI:10.1103/PhysRevD.90.114031 · 4.86 Impact Factor
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    ABSTRACT: Introducing constant background fields into the noncommutative gauge theory, we first obtain a Hermitian fermion Lagrangian which involves a Lorentz violation term, then we generalize it to a new deformed canonical noncommutation relations for fermion field. Massless neutrino oscillation in the deformed canonical noncommutation relations is analyzed. The restriction of the noncommutative coefficients is also discussed. By comparing with the existing experimental data of conventional neutrino oscillations, the order of noncommutative deformed coefficients is given from different ways.
    Physical Review D 12/2014; 91(3). DOI:10.1103/PhysRevD.91.036009 · 4.86 Impact Factor
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    ABSTRACT: We derive the curvature induced quantum-mechanical potential of a neutral spinless particle constrained to move on a surface of revolution. Using the thin-layer quantization scheme, we decompose the tangent component of the Schr\"odinger equation from the transverse component. The tangent Schr\"odinger equation is separated into angular and axial direction in cylindrical coordinate. The exactly solvable model with the shape of truncated cone is investigated and its geometrical induced states are given analytically. With hard wall boundary condition, we find that energy levels and energy differences decrease monotonically with raising the height and generatrix slope of the geometry. Moreover, particles possessing higher kinetic energy tends to occupy the place with greater curvature. These results do good favor to concerned nano-structure experiment.
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    Yong-Long Wang · Long Du · Chang-Tan Xu · Xiao-Jun Liu · Hong-Shi Zong
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    ABSTRACT: We derive the Pauli equation for a charged spin particle confined to move on a spatially curved surface $\mathcal{S}$ in an electromagnetic field. Using the thin-layer quantization scheme to constrain the particle on $\mathcal{S}$, and in the transformed spinor representations, we obtain the well-known geometric potential $V_g$ and the presence of $e^{-i\varphi}$, which can generate additive spin connection geometric potentials by the curvilinear coordinate derivatives, and we find that the two fundamental evidences in the literature [Giulio Ferrari and Giampaolo Cuoghi, Phys. Rev. Lett. 100, 230403 (2008).] are still valid in the present system without source current perpendicular to $\mathcal{S}$. Finally, we apply the surface Pauli equation to spherical, cylindrical, and toroidal surfaces, in which we obtain expectantly the geometric potentials and new spin connection geometric potentials, and find that only the normal Pauli matrix appears in these equations.
    Physical Review A 11/2014; 90(4). DOI:10.1103/PhysRevA.90.042117 · 2.99 Impact Factor
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    ABSTRACT: Based on the study of the linear response of the fermion propagator in the presence of an external scalar field, we calculate the staggered spin susceptibility in the low energy limit in the framework of the Dyson-Schwinger approach. We analyze the effect of a finite gauge boson mass on the staggered spin susceptibility in both Nambu phase and Wigner phase. It is found that the gauge boson mass suppresses the staggered spin susceptibility in Wigner phase. In addition, we try to give an explanation for why the antiferromagnetic spin correlation increases when the doping is lowered.
    Physical Review D 10/2014; 90(7). DOI:10.1103/PhysRevD.90.073013 · 4.86 Impact Factor
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    Pei-lin Yin · Zhu-fang Cui · Hong-tao Feng · Hong-shi Zong
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    ABSTRACT: At zero temperature and density, the nature of the chiral phase transition in QED3 with NfNf massless fermion flavors is investigated. To this end, in Landau gauge, we numerically solve the coupled Dyson–Schwinger equations for the fermion and boson propagator within the bare and simplified Ball-Chiu vertices separately. It is found that, in the bare vertex approximation, the system undergoes a high-order continuous phase transition from the Nambu–Goldstone phase into the Wigner phase when the number of fermion flavors NfNf reaches the critical number Nf,cNf,c, while the system exhibits a typical characteristic of second-order phase transition for the simplified Ball-Chiu vertex.
    Annals of Physics 09/2014; 348. DOI:10.1016/j.aop.2014.06.004 · 3.07 Impact Factor
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    Hong-tao Feng · Jian-Feng Li · Yuan-mei Shi · Hong-shi Zong
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    ABSTRACT: Based on the feature of chiral susceptibility and thermal susceptibility at finite temperature, the nature of chiral phase transition around the critical number of fermion flavors ($N_c$) and the critical temperature ($T_c$) at a fixed fermion flavors number in massless QED$_3$ are investigated. It is showed that, at finite temperature the system exhibits a second-order phase transition at $N_c$ or $T_c$ and each of the estimated critical exponents is less than 1, while it reveals a higher-order continuous phase transition around $N_c$ at zero temperature.
    Physical Review D 08/2014; 90(6). DOI:10.1103/PhysRevD.90.065005 · 4.86 Impact Factor

Publication Stats

895 Citations
413.22 Total Impact Points

Institutions

  • 1994–2015
    • Nanjing University
      • Department of Physics
      Nan-ching, Jiangsu Sheng, China
  • 2014
    • Anyang Normal University
      Chang-te, Henan Sheng, China
  • 2013
    • National Space Science
      Peping, Beijing, China
  • 2011
    • Chongqing Jiaotong University
      Ch’ung-ch’ing-shih, Chongqing Shi, China
  • 2010
    • Government of the People's Republic of China
      Peping, Beijing, China
  • 1998–2002
    • Academia Sinica
      T’ai-pei, Taipei, Taiwan
    • China Institute of Atomic Energy
      Peping, Beijing, China