Regular and Black Hole Skyrmions with Axisymmetry

It has been known that a B=2 skyrmion is axially symmetric. We consider the Skyrme model coupled to gravity and obtain static axially symmetric regular and black hole solutions numerically. Computing the energy density of the skyrmion, we discuss the effect of gravity to the energy density and baryon density of the skyrmion.     

The generator coordinate spin and isospin projection in the chiral bag plus skyrmion hybrid model

We study the baryon properties in the chiral bag plus skyrmion hybrid model. To describe the physical baryon state, we apply the generator coordinate projection method (GCM) instead of the widely used semiclassical collective coordinate method (CCM). The intrinsic state for the skyrmion is constructed as the coherent state and the valence quarks are treated explicitly. The nucleon and delta masses and the axial coupling constant g_A are investigated. Tha masses are significantly reduced from the large hedgehog mass due to the quantum effects in the GCM and a small g_A in the CCM is enhanced as a result of finite N_c. Agreement with experimental data of these quantities is much improved compared to the semiclassical CCM.     

Bound state approach for strange dibaryons in the skyrme model

The bound state approach to strange dibaryons in the Skyrme model is extended to baryon number n > 1. Kaon bound states are obtained in a (variational) axially symmetric SU (2) skyrmion background field. Collective quantization of isospin and spatial zero modes leads to dibaryon quantum states. These are classified in flavor multiplets.     

斯格明子在均匀磁场中的性质（英文）

主要研究了斯格明子的质量和电荷半径在均匀磁场中的变化性质。基于系统所拥有的对称性,本研究采用一组拥有轴对称性的拟设方程式以便进行研究工作。本研究证明重子数即使在非零磁场中也是一个守恒量。本研究发现随着磁场强度的增加,斯格明子的质量和电荷半径对磁场的依赖方式不同:由于磁场的主要贡献由线性项过渡到平方项,因此随着磁场的增强,斯格明子的质量先下降然后上升;与此相对应的,随着磁场的增强,斯格明子的电荷半径先增加然后减小。最后,本研究发现磁星内部的状态方程式对磁场强度有强烈的依赖,因此在理论计算磁星的质量上限时应考虑磁场所产生的影响。The mass and shape of skyrmion in an uniform magnetic field are investigated. Base on the symmetry of the system, an axially symmetric ansatz of the soliton is proposed to perform the study. The baryon number is shown to be always conserved even in a nonzero magnetic background. It is found that with the increase of the strength of magnetic field, the static mass of skyrmion first decreases then increases, as the dominant role shift from the linear term of magnetic field to the quadratic term of magnetic field, while the soliton size first increase then decrease. Finally, in the core part of magnetar, the equation of state have strong dependence of magnetic field, which also modifies the mass limit for magnetar.     

Non-rigid quantization of the Skyrmion: Translational degrees of freedom

We present a non-rigid quantization scheme for the translational degrees of freedom of the skyrmion, using the Dirac formalism for constrained systems. In this scheme, one can derive a systematic semiclassical expansion which yields a correct soft-pion limit and gives a proper treatment of retardation. We discuss the pionbaryon vertex and the baryon form factor.     

周期性应变调控斯格明子在纳米条带中的运动

斯格明子是一种拓扑稳定的手性自旋结构,凭借其在磁性赛道存储器和自旋电子器件方面的巨大应用潜力而受到研究人员的广泛关注.为了使斯格明子能够更好地应用于磁性赛道存储器,研究斯格明子在纳米条带中的运动行为就变得非常重要.本文主要研究了存在周期性应变的纳米条带中铁磁斯格明子和反铁磁斯格明子在电流驱动下的运动行为.研究结果表明:周期性应变使得驱动电流存在一个临界电流密度,只有当电流密度大于临界电流密度时斯格明子才能够在纳米条带中连续移动.临界电流密度随应变振幅的增加而增加,随应变周期的增加而减小.铁磁斯格明子在周期性应变的调制下会产生周期性运动,轨迹为波浪式,其横向速度受到边界的影响,而纵向速度则与应变梯度成正比.反铁磁斯格明子在周期性应变调控下运动方向不变,但其移动速度则剧烈变化.     

Nonextensive statistical effects in the quark-gluon plasma formation at relativistic heavy-ion collisions energies

We investigate the relativistic equation of state of hadronic matter and quark-gluon plasma at finite temperature and baryon density in the framework of the non-extensive statistical mechanics, characterized by power-law quantum distributions. We impose the Gibbs conditions on the global conservation of baryon number, electric charge and strangeness number. For the hadronic phase, we study an extended relativistic mean-field theoretical model with the inclusion of strange particles (hyperons and mesons). For the quark sector, we employ an extended MIT-Bag model. In this context we focus on the relevance of non-extensive effects in the presence of strange matter.     

Critical Dzyaloshinskii–Moriya interaction energy density for the skyrmion states formation in ultrathin ferromagnetic layer

We investigate the condition for the skyrmion state formation in ultrathin ferromagnetic layers with the Dzyaloshinskii–Moriya interaction (DMI). By using micromagnetic simulations with DMI term, we found skyrmion state is a ground state instead of a collinear single domain when DMI is larger than a critical value. When the skyrmion arrays are formed, a specific length scale of skyrmion is governed the spin configurations. We found that the critical DMI energy density for the skyrmion state is related with not only crystalline anisotropy energy, but also the dipole–dipole interaction.     

Strange Quark Matter and Strangelets in a Strong Magnetic Field

We study the stability properties of magnetized strange quark matter and strangelets under a strong magnetic field in the MIT bag model. The free energy per baryon of strange quark matter feels a great influence from the magnetic field. At the field strength about 10¹⁷G, the magnetized strange quark matter becomes more stable. Considering the finite size effect, the magnetic influence on strangelets becomes complicated. For a given magnetic field, there exists a critical baryon number, below which the magnetized strangelets have lower energy than the non-magnetized strangelets. For the field strength of 5× 10¹⁷G, the critical baryon number is A_c ～ 100. Generally, the critical baryon number increases with the decreasing external magnetic field. When the field strength is smaller than 10¹⁷G, the critical baryon number goes up to A_c～ 10⁵. The stable radius, electric charge, and quark flavor fractions of magnetized strangelets are shown.     

EOS for a QGP with a temperature and baryon chemical potential dependent bag pressure

We develop an equation of state (EOS) for the quark-gluon plasma (QGP) involving the temperature and baryon chemical potential dependent bag pressure arising due to the entropy and baryon number conservation at the phase boundary together with the Gibbs’ construction for an equilibrium phase transition. We show that the bag pressure thus obtained yields a decreasing behaviour with the increasing baryon chemical potential at a fixed temperature. Further consequences of the modified bag pressure are discussed.     

暗能量和重子数等曲率扰动

文章对作为暗能量候选者之一的Quintessence场与物质的相互作用及其在宇宙学中的应用进行了研究,通过引入Quintessence与重子流的耦合合理地解释了重子与反重子的不对称性.另外还详细地计算了重子数等曲率扰动.     

Brownian motion of massive skyrmions in magnetic thin films

We report on the thermal effects on the motion of current-driven massive magnetic skyrmions. The reduced equation for the motion of skyrmion has the form of a stochastic generalized Thiele’s equation. We propose an ansatz for the magnetization texture of a non-rigid single skyrmion that depends linearly with the velocity. By using this ansatz it is found that the skyrmion mass tensor is closely related to intrinsic skyrmion parameters, such as Gilbert damping, skyrmion-charge and dissipative force. We have found an exact expression for the average drift velocity as well as the mean-square velocity of the skyrmion. The longitudinal and transverse mobility of skyrmions for small spin-velocity of electrons is also determined and found to be independent of the skyrmion mass.     

Baryon-number-induced Chern-Simons couplings of vector and axial-vector mesons in holographic QCD

We show that holographic models of QCD predict the presence of a Chern-Simons coupling between vector and axial-vector mesons at finite baryon density. In the Anti de Sitter/Conformal Field Theory dictionary, the coefficient of this coupling is proportional to the baryon number density and is fixed uniquely in the five-dimensional holographic dual by anomalies in the flavor currents. For the lightest mesons, the coupling mixes transverse rho and a1 polarization states. At sufficiently large baryon number densities, it produces an instability, which causes the rho and a1 mesons to condense in a state breaking both rotational and translational invariance.     

Magnetic skyrmion dynamics in thin cylindrical dots

We calculate high‐frequency spin excitations of the skyrmion ground state cylindrical magnetic dots. The skyrmion is assumed to be stabilized at room temperature due to interplay of the isotropic and Dzyaloshinskii–Moriya exchange interactions, perpendicular magnetic anisotropy and magnetostatic interaction. The Skyrmion ground state is represented as combination of two radially symmetric bubble domains. To consider the Bloch‐ and Néel‐type magnetic skyrmion dynamics we apply an approximation of ultrathin domain wall between the circular domains and assume that the magnetic dot is thin enough (magnetization does not depend on the thickness coordinate). The eigenfunctions/eigenfrequencies of spin wave excitations over the skyrmion background are calculated as a function of the skyrmion radius. The developed approach allows predicting spin wave eigenfrequencies in the skyrmion ground state magnetic dots. Recent experiments on magnetic skyrmion dynamics are discussed. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Improved Gell-Mann-Okubo Relations and SU(3) Rotation Excitations of Baryon States

The corrections to the Gell-Mann-Okubo relations of baryon masses are presented in the SU(3) Skyrrne model. These corrections are calculated up to the second order in flavor breaking at the skyrmion quantum mechanics. The results are compatible with the experimental data. They could be regarded as a signal of existence of the SU(3) rotation excitation states of baryons: 27-let (with spin 1/2 or 3/2), 10^*-let (with spin 1/2) and 35-let (with spin 3/2).     

Nonsingular skyrmions for Landau levels with odd occupation number in a two-dimensional system

The number of particles, energy and other physical parameters in the presence of a skyrmion vortex have been calculated using the gradient expansion technique. Unlike other researchers, we have not used the approximation of functions projected on a single Landau level. If other Landau levels are included in the scheme, we have a simple physical model and a substantially modified expression for the skyrmion energy. Generation of one skyrmion is thermodynamically favorable, so they should emerge spontaneously near odd-integer filling factors. Zh. éksp. Teor. Fiz. 112, 1899–1914 (November 1997)     

Gravitational leptogenesis in teleparallel and symmetric teleparallel gravities

In this study, we investigate the possibilities of generating baryon number asymmetry under thermal equilibrium within the frameworks of teleparallel and symmetric teleparallel gravities. Through the derivative couplings of the torsion scalar and the non-metricity scalar to baryons, baryon number asymmetry is produced in the radiation dominated epoch. For gravitational baryogenesis mechanisms in these two frameworks, the produced baryon-to-entropy ratio is too small to be consistent with observations. However, the gravitational leptogenesis models within both frameworks have the potential to explain the observed baryon-antibaryon asymmetry.     

Characteristic predictions of topological soliton models

Characteristic predictions of the chiral soliton models (the Skyrme model and its extensions) are discussed. The chiral soliton model predictions of low-lying dibaryon states qualitatively agree with recent evidence for the existence of narrow dibaryons in reactions of the inelastic proton scattering on deuterons and the double photon radiation pp→ppγγ. The connection between magnetic moment operators and inertia tensors valid for arbitrary SU(2) skyrmion configurations allows us to estimate the electromagnetic decay width of some states of interest. Predictions of a different type are multibaryons with a nontrivial flavor (strangeness, charm, or bottom), which can be found, in particular, in high-energy heavy ion collisions. It is shown that the large-B multiskyrmions given by the rational map ansatz can be described within the domain-wall approximation or as a spherical bag with the energy and the baryon number density concentrated at the boundary.     

Axial symmetry of bound baryon number-two solution of the Skyrme model

In a Skyrme model for strong interactions we have obtained numerically the baryon number-two field configuration of minimum energy. We find that this static solution of the equations of motion has an axial symmetry. Its binding energy is 70 MeV with respect to the sum of the energy of two skyrmions with baryon number one. The baryon density of this solution has the shape of a donut (i.e., homotopic to a torus).     

Majorana zero modes induced by skyrmion lattice

One-dimensional s-wave superconductor with spin-orbit coupling is a platform for the realization of Majorana zero modes. The spin-exchange with the magnetic skyrmion lattice can induce spin-orbit coupling in a s-wave superconductor system and the effects are different from the constant spin-orbit coupling. The strength of the effective spin-orbit coupling as well as the rich topoloigcal phase diagram are directly connected to the radius of the skyrmion lattice R. We obtain the rich topological phase diagram of this system with different skyrmion lattice radii by numerically evaluating the spectrum of the system under the periodic boundary condition, and we also find the Majorana zero modes under the open boundary condition to verify the bulk-edge correspondence.