arXiv subjects

Xin-Jian Wen

Publications and source records attributed to Xin-Jian Wen.

At least 19 recordsLinked to original sources

arXiv2026

Anisotropic surface tension and stability of quark matter modified by the vector interaction

In this article, the surface tension and stability of quark matter modified by the vector interaction in a strong magnetic field are investigated in the quasiparticle model with the multiple reflection expansion. The self-consistent thermodynamic treatment of the chemical-potential-dependent quark mass is maintained by the effective bag function, which depends on both the chemical potential and the magnetic field. It is found that the vector interaction could enlarge the surface tension in both the parallel and transverse directions with respect to the magnetic field. In a stronger magnetic field region, the presence of the vector repulsive interaction leads to an increase in transverse surface tension with the magnetic field strength, which is opposite to the vanishing value without repulsive interaction in the previous work. Consequently, it is concluded that a moderate-intensity magnetic field is required for the formation of a quark matter bubble with the vector interaction. Finally, it is demonstrated that the vector interaction slightly reduces the stability of quark matter.

hep-ph↗

arXiv2025

Stability of quark matter affected by the surface tension in a strong magnetic field

The surface tension of quark matter in a strong magnetic field is investigated using a geometric approach. The interface between the hadronic phase and quark phase is determined by the Maxwell construction of the first-order transition. When surface tension is included, the free energy per baryon is no longer a monotonic function of the chemical potential. Specifically, for smaller droplets, a larger chemical potential is required to achieve a stable phase. Moreover, we find that the surface tension does not increase monotonically with the magnetic field. Finally, it is shown that stable quark matter, both with and without surface tension, can exist at a specific magnetic field strength, which would provide favorable conditions for the experimental production of quark matter.

hep-ph↗

arXiv2025

Tensor condensate accompanied by chiral transition in a strong magnetic field

We investigate tensor condensates and chiral condensates in the (2+1)-flavor Nambu-Jona-Lasinio model at finite temperature and density in the presence of a strong magnetic field. The emergence of the tensor condensate is attributed to the four-fermion interaction. It is shown that a sufficiently large chemical potential is necessary for the occurrence of a phase transition towards tensor condensate. Furthermore, we investigate the correlation between tensor condensate and spin polarization, which accounts for the oscillatory behavior of the spin polarization during the transition from the chiral condensate to tensor condensate phase.

hep-th↗

arXiv2025

Constraint on the magnetic field for the stable strange quark matter

The quasiparticle model is employed to investigate the quark matter at finite chemical potential. The effective bag constant is derived to be dependent on both the chemical potential and the magnetic field. The self-consistent thermodynamics is fulfilled that the free energy minimum corresponds to the zero pressure. It is shown that the strong magnetic field is helpful for the stabilization of the strange quark matter. However, the increase in the coupling constant and the vacuum bag constant could reduce the stability. For the absolutely stable strange quark matter, there is a lower limit of the allowed magnetic field, which rises with the increase in the coupling constant and the vacuum bag constant.

hep-ph↗

arXiv2024

QCD phase transition with non-extensive NJL model in the strong magnetic field

In this work we make use of the Nambu-Jona-Lasinio model to investigate thermodynamic properties of magnetized three-flavor quark matter. The non-equilibrium Tsallis distribution is characterized by a dimensionless non-extensive parameter $q$. We find that the system always undergoes a crossover transition for all given $q$ values and the pseudo-critical temperature decreases with the increasing non-extensive parameter. We show that the variation of the pressure and its anisotropy in parallel and perpendicular directions. However, the diamagnetic nature appears within a certain temperature range at zero chemical potential. Moreover, strong magnetic fields can affect the property of a non-extensive system by changing the magnetization significantly. At high temperatures, the paramagnetic nature always occur no matter how strong the magnetic field is. Finally, we study the effects of non-extensive parameter $q$ on the trace anomaly and the speed of sound of the system.

hep-ph↗

arXiv2024

Thermal effect in hot QCD matter in strong magnetic fields

The quasiparticle model is improved by the free magnetic contribution to investigated the QCD matter in a strong magnetic field. The temperature-dependent bag function is determined by the thermodynamic consistency to represent the difference in energy density between physical vacuum and lowest state of QCD. It is found that the positive bag function vanishes at high temperature indicating the deconfinement. The rapid decrease of the bag function in stronger magnetic fields reveals the so-called inverse magnetic catalysis. The interaction measure at high temperature remains so large that the usual Stefan-Boltzmann limit can not be reached. We suggest a limit $|q_iB_m|T^2/4$ for each landau level pressure. Finally, it is demonstrated that the positive magnetization modified by the bag function and free magnetic contribution indicates the paramagnetic characteristic of QCD matter.

hep-ph↗

arXiv2023

Finite volume effects of the Nambu-Jona-Lasinio model with the running coupling constant

With the Schwinger's proper-time formalism of the Nambu-Jona-Lasinio model, we investigate the finite volume effects in the presence of magnetic fields. Since the coupling constant $G$ can be influenced by strong magnetic fields, the model is solved with a running coupling constant $G(B)$ which is fitted by the lattice average $(Σ_u+Σ_d)/2$ and difference $Σ_u-Σ_d$. The investigation mainly focuses on the constituent quark mass and the thermal susceptibility depending on the magnetic fields, the temperatures and the finite sizes. For the model in finite or infinite volume, the magnetic fields can increase the constituent quark mass while the temperatures can decrease it inversely. There is a narrow range of the box length that makes the effects of finite volume perform prominently. The model will behave close to infinite volume limit for larger box length. It is shown that the influence of finite volume can be changed by magnetic fields and temperatures. Finally, we discuss the thermal susceptibility depending on the temperature in finite volume in the presence of magnetic fields.

hep-ph↗

arXiv2023

Medium effect on anisotropic surface tension of magnetized quark matter

The thermodynamics of finite size quark matter in the quasiparticle model is self-consistently constructed by an effective bag function, which presents the medium effect to the confinement. We obtained completely analytic surface tension in the strong magnetic field with the multiple reflection expansion. The anisotropic structure is demonstrated by the splitting of the longitudinal and transverse surface tensions. The anisotropy of the surface tension could be enhanced by an increase of the magnetic field. The analytical surface tension is modified by an additional term related to the bag function. For strong enough magnetic fields, the increase of the longitudinal surface tension is proportional to the magnetic field.On the contrary, the transverse component vanishes due to all quarks locating in the lowest landau level.

hep-ph↗

arXiv2022

Effect of anomalous magnetic moment on the chiral transition at zero temperature in a strong magnetic field

The effect of the anomalous magnetic moment (AMM) on the chiral restoration is investigated at zero temperature in the strong magnetic fields with the vacuum magnetic regularization scheme. It is shown that the chiral restoration diagram sensitively depends on the AMM in the ultrastrong magnetic fields. In our work, the parameterization of AMM is employed as proportional to the square of the chiral condensate. The critical chemical potential is found to decrease linearly by the increasing coefficient in the AMM scale. At a smaller scale of the AMM, the critical chemical potential could go down and then grow up as the magnetic field increases. But at a larger scale, the magnetic catalysis on the critical chemical potential would not happen anymore.

hep-ph↗

arXiv2022

Thermodynamics of PNJL at zero temperature in a strong magnetic field

In this paper, the deconfinement and chiral restoration transitions in strong magnetic field is realized at zero temperature in the Polyakov Nambu$-$Jona-Lasinio model. We provide the thermodynamic treatment to mimic the deconfinement phase transition at zero temperature together with the entangled scalar and vector interactions coupled with the Polyakov loop. The magnetic catalysis is found by a rising behavior of the critical chemical potential for the first-order deconfinement phase transition. While the magnetic catalysis on the chiral restoration could convert to inverse magnetic catalysis under the running coupling interaction ansatz. Furthermore, the stronger magnetic field makes the possible quarkyonic phase window to be enlarged under the running coupling interaction.

hep-ph↗

arXiv2022

Landau quantization and spin polarization of cold magnetized quark matter

The magnetic field and density behaviors of various thermodynamic quantities of strange quark matter under compact star conditions are investigated in the framework of the thermodynamically self-consistent quasiparticle model. For individual species, a larger number density $n_i$ leads to a larger magnetic field strength threshold that align all particles parallel or antiparallel to the magnetic field. Accordingly, in contrast to the finite baryon density effect which reduces the spin polarization of magnetized strange quark matter, the magnetic field effect leads to an enhancement of it. We also compute the sound velocity as a function of the baryon density and find the sound velocity shows an obvious oscillation with increasing density. Except for the oscillation, similar to the zero-magnetic field case that the sound velocity grows with increasing density and approaches the conformal limit $V_s^2=1/3$ at high densities from below.

hep-ph↗

arXiv2021

The compressibility of quark matter under strong magnetic field in the NJL model

The compressibility of magnetized quark matter is investigated in the SU(2) NJL model. The increases of the chemical potential and the temperature can reduce the compressibility, and lead to the much stiffer equation of state. The variation of the compressibility with the magnetic field will depend on the phase region. Due to the anisotropic structure, the compressibility is different in the directions parallel and perpendicular to the field. The discontinuity of longitudinal compressibility with the chemical potential and the temperature captures the signature of a first-order chiral phase transition and the crossover at high temperature. Moreover, the magnetic-field-and-temperature running coupling would have an important effect on the position of the phase transition. Under the lowest landau level approximation at zero temperature, the longitudinal compressibility has a direct inverse proportional relation to the magnetic field strength and the chemical potential square as $κ^\parallel_{\mathrm{LLL},χ}\propto1/(eB μ^2)$.

hep-ph↗

arXiv2019

Multisource thermal model to the transverse momentum spectra in pp collisions at RHIC and LHC energies

In this paper, an improved multi-source thermal model is used to analyze the transverse momentum spectra in $pp$ collisions at high energies ranging from $\sqrt{\mathrm{\it s_{NN}}}$ = 62.4 GeV to 7 TeV. We give a detailed comparison between the theoretical results and experimental data at RHIC and LHC energies. It is shown that the excitation factors of emission sources depend linearly on ln$\sqrt{\mathrm{\it s_{NN}}}$ in the framework. Based on the variation regularity of the source-excitation factors, transverse momentum spectra are predicted in $pp$ collisions at higher energies, potential future $pp$ colliders operating at $\sqrt{\mathrm{\it s_{NN}}}$ = 33 and 100 TeV.

hep-ph↗

arXiv2016

Landau levels of cold dense quark matter in a strong magnetic field

The occupied Landau levels of strange quark matter are investigated in the framework of the SU(3) NJL model with a conventional coupling and a magnetic-field dependent coupling respectively. At lower density, the Landau levels are mainly dominated by u and d quarks. Threshold values of the chemical potential for the s quark onset are shown in the $μ$-$B$ plane. The magnetic-field-dependent running coupling can broaden the region of three-flavor matter by decreasing the dynamical masses of $s$ quarks. Before the onset of $s$ quarks, the Landau level number of light quarks is directly dependent on the magnetic field strength $B$ by a simple inverse proportional relation $k_{i,\mathrm{max}}\approx B_i^0/B$ with $B_d^0=5\times 10^{19}$ G, which is approximately 2 times $B_u^0$ of $u$ quarks at a common chemical potential. When the magnetic field increases up to $B^0_d$, almost all three flavors are lying in the lowest Landau level.

hep-ph↗

arXiv2016

Magnetized quark matter with a magnetic-field dependent coupling

It was recently derived that the QCD running coupling is a function of the magnetic field strength under the strong magnetic field approximation. Inspired by this progress and based on the self-consistent solutions of gap equations, the properties of two-flavor and three-flavor quark matter are studied in the framework of the Nambu-Jona-Lasinio model with a magnetic-field dependent running coupling. We find that the dynamical quark masses as functions of the magnetic field strength are not monotonous in the fully chirally broken phase. Furthermore, the stability of magnetized quark matter with the running coupling is enhanced by lowering the free energy per baryon, which is expected to be more stable than that of the conventional constant coupling case. It is concluded that the magnetized strange quark matter described by running coupling can be absolutely stable.

hep-ph↗

arXiv2014

Particle production in relativistic $pp$($\overline{p}$) and $AA$ collisions at RHIC and LHC energies with Tsallis statistics using the two-cylindrical multisource thermal model

An improved Tsallis statistics is implemented in a multisource thermal model to describe systematically pseudorapidity spectra of charged particles produced in relativistic nucleon-nucleon ($pp$ or $p\overline{p}$) collisions at various collision energies and in relativistic nucleus-nucleus ($AA$) collisions at different energies with different centralities. The results with Tsallis statistics using the two-cylindrical multisource thermal model are in good agreement with the experimental data measured at RHIC and LHC energies. It is found that the rapidity shifts of longitudinal sources increase linearly with collision energies and centralities in the framework. According to the laws, we also give a prediction of the pseudorapidity distributions in $pp$($\overline{p}$) collisions at higher energies.

hep-ph↗

arXiv2013

Color-flavor locked strange quark matter in a strong magnetic field

The quark quasiparticle model is extended to study the properties of color-flavor locked strange quark matter at finite chemical potential and in a strong magnetic field. We present a self-consistent thermodynamic treatment by employing a chemical potential dependent bag function. It is found that the magnetized color-flavor-locked (MCFL) matter is more stable than other phases within a proper magnitude of magnetic field. The stability window is graphically shown for the MCFL matter compared with ordinate magnetized matter. The anisotropic structure of MCFL matter is dominated by the magnetic field and almost independent of the energy gaps. A critical maximum magnetic field of about $1.56\times 10^{18}$ G is found, under which MCFL matter is absolutely stable with respect to nuclear matter.

hep-ph↗

arXiv2013

Equation of state in hybrid stars and the stability window of quark matter

Properties of hybrid stars with a mixed phase composed of asymmetric nuclear matter and strange quark matter are studied. The quark phase is investigated by the quark quasiparticle model with a self-consistent thermodynamic and statistical treatment. We present the stability windows of the strange quark matter with respect to the interaction coupling constant versus the bag constant. We find that the appearance of the quark-hadron mixed phases is associated with the meta-stable or unstable regions of the pure quark matter parameters. The mass-radius relation of the hybrid star is dominated by the equation of state of quark matter rather than nuclear matter. Due to the appearance of mixed phase, the mass of hybrid star is reduced to 1.64 M$_{\odot}$ with radius 10.6 km by comparison with neutron star.

nucl-th↗