Hong-Shi Zong

Nanjing University, Nan-ching, Jiangsu Sheng, China

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Publications (142)442.08 Total impact

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    ABSTRACT: In a realistic interacting system described by (2+1)-dimensional quantum electrodynamics (QED3), there is always a certain number of impurities by which fermions are scattered. In general, impurity scattering can generate a finite density of states at the Fermi level, which screens the temporal component of the gauge field. This effect is expected to weaken dynamical fermion mass generation. Within the Born approximation, by introducing a damping term in the energy component of the fermion propagator, the influences of finite temperature and impurity scattering on the chiral phase transition in QED3 are investigated. Pursuing this aim, we solve the Dyson-Schwinger equations for the fermion and boson propagators to the leading order in 1/Nf expansion at zero frequency and then calculate the chiral condensate, the chiral susceptibility, and the thermal susceptibility within a range of the impurity scattering rates Γ and the numbers of fermion flavors Nf. It is found that impurity scattering leads to an obvious suppression of the dynamical fermion mass generation and critical temperature Tc.
    No preview · Article · Jan 2016
  • Yong-Long Wang · Guo-Hua Liang · Hua Jiang · Wei-Tao Lu · Hong-Shi Zong
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    ABSTRACT: We employ a model introduced by a periodically corrugated thin layer to investigate the effects of the geometrical curvature on transmission. The geometric potential is obtained by performing the thin-layer quantization procedure. With the help of the transfer matrix method the transmission probability is calculated. We find that the transmission gaps emerge from the corrugations, and in the tunneling domains the peaks and valleys are mainly constructed by the boundaries, slightly modified by the layer thickness. These results can provide an access to design a curvature-tunable filter.
    No preview · Article · Dec 2015
  • Shu-Sheng Xu · Yu Jiang · Chao Shi · Zhu-Fang Cui · Hong-Shi Zong
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    ABSTRACT: Generally speaking, the quark propagator is dependent on the quark chemical potential in the dense quantum chromodynamics (QCD). By means of the generating functional method, we prove that the quark propagator actually depends on p4 + iμ from the first principle of QCD. The relation between quark number density and quark condensate is discussed by analyzing their singularities. It is concluded that the quark number density has some singularities at certain μ when T = 0, and the variations of the quark number density as well as the quark condensate are located at the same point. In other words, at a certain μ the quark number density turns to nonzero, while the quark condensate begins to decrease from its vacuum value.
    No preview · Article · Dec 2015 · Chinese Physics Letters
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    ABSTRACT: It is commonly accepted that the system undergoes a crossover at high temperature and low chemical potential beyond the chiral limit case, and the properties of the crossover region are important for researchers to understand the nature of strong interacting matters of quantum chromodynamics (QCD). Since at present there is no exact order of parameters of the phase transitions beyond the chiral limit, QCD susceptibilities are widely used as indicators. In this work various susceptibilities are discussed in the framework of DysonSchwinger equations. The results show that different kinds of susceptibilities give the same critical end point, which is the bifurcation point of the crossover region and the first order phase transition line of QCD. Nevertheless, different pseudocritical points are found in the temperature axis. We think that defining a critical band is more suitable in the crossover region.
    No preview · Article · Dec 2015 · Chinese Physics Letters
  • Hao Gong · Xiao-Xia Ruan · Hou-Rong Pang · Hong-Shi Zong
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    ABSTRACT: In this paper, taking into account the effect of the induced interaction, we calculate the energy of ultracold Fermi gases at unitarity in the framework of non-self-consistent T-matrix approximation (nTMA) above the critical temperature and compare the result with the experimental data and other theoretical calculation without induced interaction. Our calculated chemical potential is higher than the experimental data, but our calculated energy obtains a good agreement with Tokyo experiment for temperature range between (Formula presented.) and (Formula presented.).
    No preview · Article · Nov 2015 · Modern Physics Letters B
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    Yong-Long Wang · Hong-Shi Zong
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    ABSTRACT: We clearly refine the fundamental framework of the thin-layer quantization procedure, and further develop the procedure by taking the proper terms of degree one in $q_3$ ($q_3$ denotes the curvilinear coordinate variable perpendicular to curved surface) back into the surface quantum equation. The well-known geometric potential and kinetic term are modified by the surface thickness. Applying the developed formalism to a toroidal system obtains the modification for the kinetic term and the modified geometric potential including the influence of the surface thickness.
    Full-text · Article · Nov 2015
  • Qiang Zhang · Yong-Feng Huang · Hong-Shi Zong
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    ABSTRACT: The afterglows of gamma-ray bursts (GRBs) are believed to originate from the synchrotron emission of shock-accelerated electrons produced by the interaction between the outflow and the external medium. The accelerated electrons are usually assumed to follow a power-law energy distribution with an index of p. Observationally, although most GRB afterglows have a p larger than 2, there are still a few GRBs suggestive of a hard () electron spectrum. The well-sampled broad-band afterglow data for GRB 091127 show evidence of a hard electron spectrum and strong spectral evolution, with a spectral break moving from high to lower energies. The spectral break evolves very fast and cannot be explained by the cooling break in the standard afterglow model, unless evolving microphysical parameters are assumed. In addition, the multi-band afterglow light curves show an achromatic break at around 33 ks. Based on the model of a hard electron spectrum with an injection break, we interpret the observed spectral break as the synchrotron frequency corresponding to the injection break, and the achromatic break as a jet break caused by the jet-edge effect. It is shown that the spectral evolution and the multi-band afterglow light curves of GRB 091127 can be well reproduced by this model. © 2015. The American Astronomical Society. All rights reserved..
    No preview · Article · Sep 2015 · The Astrophysical Journal
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    Tong Zhao · Shu-Sheng Xu · Yan Yan · Xin-Lian Luo · Xiao-Jun Liu · Hong-Shi Zong
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    ABSTRACT: In this paper we introduce an equation of state (EOS) of quark matter within the framework of Dyson-Schwinger equations (DSEs) to study the structure of compact stars. The smooth crossover from hadronic matter to quark matter in the hybrid star is studied. We compare different strategies to obtain crossover EOSs and find a new way to construct two-solar-mass hybrid stars with even a relatively soft quark EOS, while earlier works show that the quark EOS should be stiff enough to support a massive hybrid star.
    Preview · Article · Sep 2015 · Physical Review D
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    ABSTRACT: A confining, symmetry-preserving, Dyson-Schwinger equation treatment of a vector-vector contact interaction is used to formulate Faddeev equations for the nucleon and Delta-baryon in which the kernel involves dynamical dressed-quark exchange and whose solutions therefore provide momentum-dependent Faddeev amplitudes. These solutions are compared with those obtained in the static approximation and with a QCD-kindred formulation of the Faddeev kernel. They are also used to compute a range of nucleon properties, amongst them: the proton's sigma-term; the large Bjorken-x values of separate ratios of unpolarised and longitudinally-polarised valence u- and d-quark parton distribution functions; and the proton's tensor charges, which enable one to directly determine the effect of dressed-quark electric dipole moments (EDMs) on neutron and proton EDMs.
    Full-text · Article · Sep 2015 · Physical Review D
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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 quantum chromodynamics. The multi-solution region of the Nambu and Wigner ones 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.
    Preview · Article · Aug 2015 · European Physical Journal C
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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.
    Preview · Article · Jun 2015 · International Journal of Modern Physics A
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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.
    Preview · Article · Jun 2015 · International Journal of Modern Physics A
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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 $\mu_5$.
    Preview · Article · May 2015 · Physical Review D
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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 $Q^2 \gtrsim 3 m_N^2$.
    Full-text · Article · Apr 2015 · Physical Review Letters
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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.
    Full-text · Article · Apr 2015 · Annals of Physics
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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.
    Preview · Article · Apr 2015 · Physical Review D
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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.
    Preview · Article · Mar 2015 · Physical Review D
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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.
    Full-text · Article · Feb 2015
  • 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.
    No preview · Article · Feb 2015 · Physical Review D
  • 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.
    No preview · Article · Feb 2015 · Chinese Physics Letters

Publication Stats

1k Citations
442.08 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
  • 1998-2002
    • Academia Sinica
      T’ai-pei, Taipei, Taiwan
    • China Institute of Atomic Energy
      Peping, Beijing, China