Isometric motion in relativistic magnetohydrodynamics

The general relativistic barometric formulas of a perfect charged relativistic ther modynamical fluid with constant magnetic permeability and infinite conductivity are deduced if the space-time, in which this fluid is moving, has two Killing vector fields: the first collinear to the 4-velocity with the second one proportional to the magnetic field.     

Isometric motion in relativistic magnetohydrodynamics

It is shown that if the flow of a plasma coupled to a frozen-in magnetic field is isometric, the velocity field, the vorticity tensor and the four-vector magnetic field are invariant under the group of motions. A generalization of Ferraro's theorem of isorotation and of the Bernoulli's theorem for force-free fluids is found.     

Bose-Einstein condensation in relativistic field theories far from equilibrium

The formation of Bose condensates far from equilibrium can play an important role in our understanding of collision experiments of heavy nuclei or for the evolution of the early Universe. In the relativistic quantum world particle number changing processes can counteract Bose condensation, and there is a considerable debate about the relevance of this phenomenon in this context. We show that the involved question of Bose condensation from initial overpopulation can be answered for the example of scalar field theories. Condensate formation occurs as a consequence of an inverse particle cascade with a universal power-law spectrum. This particle transport towards low momenta is part of a dual cascade, in which energy is also transferred by weak wave turbulence towards higher momenta. To highlight the importance of number changing processes for the subsequent decay of the condensate, we also compare to nonrelativistic theories with exact number conservation. We discuss the relevance of these results for non-Abelian gauge theories.     

Fluid-magnetic helicity in axisymmetric stationary relativistic magnetohydrodynamics

The present work is intended to gain a fruitful insight into the understanding of the formations of magneto-vortex configurations and their role in the physical processes of mutual exchange of energies associated with fluid’s motion and the magnetic fields in an axisymmetric stationary hydromagnetic system subject to strong gravitational field (e.g., neutron star/magnetar). It is found that the vorticity flux vector field associated with vorticity 2-form is a linear combination of fluid’s vorticity vector and of magnetic vorticity vector. The vorticity flux vector obeys Helmholtz’s flux conservation. The energy equation associated with the vorticity flux vector field is deduced. It is shown that the mechanical rotation of vorticity flux surfaces contributes to the formation of vorticity flux vector field. The dynamo action for the generation of toroidal components of vorticity flux vector field is described in the presence of meridional circulations. It is shown that the stretching of twisting magnetic lines due to differential rotation leads to the breakdown of gravitational isorotation in the absence of meridional circulations. An explicit expression consists of rotation of vorticity flux surface, energy and angular momentum per baryon for the fluid-magnetic helicity current vector is obtained. The conservation of fluid-magnetic helicity is demonstrated. It is found that the fluid-magnetic helicity displays the energy spectrum arising due to the interaction between the mechanical rotation of vorticity flux surfaces and the fluid’s motion obeying Euler’s equations. The dissipation of a linear combination of modified fluid helicity and magnetic twist is shown to occur due to coupled effect of frame dragging and meridional circulation. It is found that the growing twist of magnetic lines causes the dissipation of modified fluid helicity in the absence of meridional circulations.     

Structure and evolution of shock waves in relativistic magnetohydrodynamics

We derive the existence conditions for relativistic shock waves propagating in a perfectly conducting fluid with a general equation of state that guarantees that the stationary wave has a continuous profile in the presence of weak viscosity. To this end we study the one-dimensional solutions of the magnetohydrodynamic equations with a relativistic viscosity tensor. We allow for anomalous regions of thermodynamic variables and do not use the well-known condition for the convexity of Poisson adiabats. The results lead to relationships among the velocities of magnetoacoustic, Alfvén, and shock waves in front of and behind the discontinuity that prove to be more stringent than the corollaries of the evolution conditions. In the nonrelativistic case and in parallel and perpendicular shock waves, any difference between the two conditions disappears. Zh. éksp. Teor. Fiz. 114, 881–891 (September 1998)     

Nuclear properties far from the stability line in the relativistic mean field theory

We study the nuclear properties far from the stability line in the relativistic mean field theory. We find that the parameter set NL 1 provides very good results on binding energies of unstable nuclei, while NL2 results are not good, although both parameter sets give equally good results on nuclear properties for stable nuclei. We discuss the neutron number dependence of the proton and the neutron root mean square radii of proton magic nuclei.     

The relativistic center of mass in field theory with spin

In order to unravel the origin of the nucleon spin, one has to study in detail the question of orbital angular momentum, and in particular the reference point about which it is defined. With this in mind, we review the concept of relativistic center of mass, generalize the discussion to the case of asymmetric energy-momentum tensors, and establish the link with the light-front formalism. We find that the p-wave in the Dirac plane-wave solutions arises from a relativistic quantum-mechanical effect which forces the canonical reference point to depend on the observer. This explains why longitudinal spin is much simpler to study than transverse spin. It is also the reason behind the observation of induced shifts and distortions in the parton distributions defined within the light-front formalism.     

Structure of nuclei far from the stability in relativistic approach

The recent progress of the relativistic many-body approach by the group at Peking University will be reviewed. In particular, axially deformed relativistic Hartree-Bogoliubov approach in Woods-Saxon basis aiming at halo nucleus, time-odd triaxial RMF approach, the adiabatic and configuration-fixed constrained triaxial RMF approaches, a Reflection ASymmetric RMF (RAS-RMF) approach, and a new relativistic Hartree-Fock (RHF) approach with density-dependent σ,ω,ρ and π meson-nucleon couplings for finite nuclei and nuclear matter, will be highlighted.     

相对论磁控管中自磁场的影响

针对相对论磁控管中自磁场的产生与分布、自磁场对电子运动的影响以及自磁场对互作用的影响进行了深入分析。分析认为,由于自磁场分布的不对称,自磁场对不同区域电子束的作用不同。加速器一侧的电子束受到更明显的自磁场作用,促使此区域的电子束角向速度增加,直接激化模式竞争。同时,如果阴极比较靠近加速器一侧的1/4区域(距磁控管对称中心大约1/4高度）,模式竞争将进一步被激化。     

Criterion for existence of shock waves in relativistic magnetohydrodynamics with a general equation of state

Relativistic stationary shock waves in an ideal conducting fluid are studied for the general equation of state. We use small viscosity arguments to obtain a criterion that selects physically admissible shock transitions without any supposition about convexity of the Poisson adiabats. The relations between the magnetosound speeds and the speed of the shock obtained as a consequence of this criterion reveal specific differences between relativistic considerations versus classical ones.     

The classical and relativistic concepts of mass

An elementary presentation is given of classical and relativistic collision dynamics based upon the principle of conservation of momentum. The concepts of mass are shown to be implicitly defined and their basic properties are rigorously derived and discussed. Luxons and tachyons are treated on the same footing as material particles.     

Solitons in relativistic mean field models

Assuming that the nucleus can be treated as a perfect fluid we study the conditions for the formation and propagation of Korteweg–de Vries (KdV) solitons in nuclear matter. The KdV equation is obtained from the Euler and continuity equations in nonrelativistic hydrodynamics. The existence of these solitons depends on the nuclear equation of state, which, in our approach, comes from well-known relativistic mean field models. We reexamine early works on nuclear solitons, replacing the old equations of state by new ones, based on QHD and on its variants. Our analysis suggests that KdV solitons may indeed be formed in the nucleus with a width which, in some cases, can be smaller than one Fermi.     

MFCG 2维磁流体力学程序中磁场计算的改进

 定子线圈中的电流在空间中产生的磁场是金属导体（套筒）膨胀压缩的主要对象,该磁场直接影响爆磁压缩发生器输出电流脉冲的大小。给出了面电流分布下2维磁场的计算公式,较点电流分布下的磁场公式更能细致准确地反映出磁场的变化。数值结果表明:面电流分布下的磁场公式不仅能准确地描述磁场的变化,而且计算效率大大提高,节约了计算时间。     

Current elements in relativistic field theory

Many previously reported experiments involving electrical circuits have demonstrated effects thought to be beyond the scope of modern relativistic field theory. The troubling effects include unexpected external electromotive forces and internal ponderomotive forces. The existence of such forces challenges long-cherished beliefs in relativistic field theory. The present note proposes a possible resolution for this situation.     

MFCG 2维磁流体力学程序中磁场计算的改进

定子线圈中的电流在空间中产生的磁场是金属导体（套筒）膨胀压缩的主要对象,该磁场直接影响爆磁压缩发生器输出电流脉冲的大小。给出了面电流分布下2维磁场的计算公式,较点电流分布下的磁场公式更能细致准确地反映出磁场的变化。数值结果表明:面电流分布下的磁场公式不仅能准确地描述磁场的变化,而且计算效率大大提高,节约了计算时间。     

Particles and propagators in relativistic thermo field theory

Based on a new spectral representation of thermal correlation functions, a general characterization of stable particles in relativistic thermo field theory is given. Such particles manifest themselves by specific discrete contributions in the spectral functions and can thus be identified unambiguously.     

Near field and far field power distributions in a multimode graded fibre

It is shown in this paper that the near field and far field power distributions corresponding to any distribution of rays in an arbitrary graded fibre, reach a steady state along the fibre. This steady state is usually a function of the input distribution of rays and of the refractive index profile of the fibre. The case of parallel beam injection is considered and an analytical expression for the near field power distributions for any arbitrary profile is found. This suggests a new method of refractive index profile measurement which is free of leaky ray corrections and can be very sensitive near the optimum profile for time dispersion.