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1.
In the framework of a (2+1)-dimensional P-even gauge theory based on the massive Gross–Neveu model, we show that an external magnetic field induces the P-parity-breaking phase transition of the first order. A dynamical generation of the Chern–Simons term and fractional particle spin and statistics occurs at the critical point. The results in the paper can be interesting in connection with recently discovered phase transitions in high-temperature superconductors. 相似文献
2.
Davide Catania 《Annali dell'Universita di Ferrara》2010,56(1):1-20
We prove local and global existence results for the Cauchy problem of a regularized magnetohydrodynamic-α model with viscous velocity field and no magnetic diffusivity for an incompressible fluid. Such a model is introduced in
analogy with the Navier–Stokes equation to study the turbulent behavior of fluids in presence of a magnetic field. We consider
the case of two space dimension. 相似文献
3.
V. R. Khalilov 《Theoretical and Mathematical Physics》1999,119(1):481-492
In the problem of a two-dimensional hydrogen-like atom in a magnetic field background, we construct quasi-classical solutions
and the energy spectrum of the Dirac equation in a strong Coulomb field and in a weak constant homogeneous magnetic field
in 2+1 dimensions. We find some “exact” solutions of the Dirac and Pauli equations describing the “spinless” fermions in strong
Coulomb fields and in homogeneous magnetic fields in 2+1 dimensions.
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 119, No. 1, pp. 105–118, April, 1999. 相似文献
4.
M. Fabrizio G. Matarazzo M. Pecoraro 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2011,24(2):1013-1026
In this paper, by an extension of the Ginzburg–Landau theory, we propose a mathematical model describing hard magnets within
which we are able to explore the para–ferromagnetic transition and by using the Landau–Lifshitz–Gilbert equation, to study
the 3D evolution of magnetic field. Finally, the hysteresis loops are obtained and represented by numerical implementations. 相似文献
5.
The Zubarev nonequilibrium statistical operator is used to describe the generalized hydrodynamic state of a magnetic fluid
in an external magnetic field. The magnetic fluid is modeled with “liquid-state” and “magnetic” subsystems described using
the classical and quantum statistics methods respectively. Equations of the generalized statistical hydrodynamics for a magnetic
fluid in a nonhomogeneous external magnetic field with the Heisenberg spin interaction are derived for “liquid-state” and
“magnetic” subsystems characterized by different nonequilibrium temperatures. These equations can be used to describe both
the weakly and strongly nonequilibrium states. Some limiting cases are analyzed in which the variables of one of the subsystems
can be formally neglected.
Translated from Teoreticheskaya i Matematicheskaya Fizika. Vol. 115, No. 1, pp. 132–153, April, 1998. 相似文献
6.
By means of ‘deep integration’ observations of a videomagnetograph the vector magnetic field was first systematically measured
near the solar south polar region on April 12, 1997 when the Sun was in the minimal phase between the 22nd and 23rd solar
cycle. It was found that the polar magnetic field deviated from the normal of solar surface by about 42.2° ± 3.2°, a stronger
magnetic element may have smaller inclination, and that within the polar cap above heliolatitude of 50°, the unsigned and
net flux densities were 7.8 × 10−4) T and −3.4×10−4T, respectively, and consequently, the unsigned and net fluxes were about 5.5 × 1022 and − 2.5 × 1022 Mx. The net magnetic flux, which belongs to the large-scale global magnetic field of the Sun, roughly appmaches the order
of the interplanetary magnetic field (IMF) measured at distance of 1 AU.
Project supported by the National Natural Science Foundation of China (Grant No. 19791090). 相似文献
7.
V. B. Gorskii 《Computational Mathematics and Modeling》1997,8(1):31-33
The classical conservation theorems for magnetic force lines, magnetic flux through a fluid surface, and intensity of magnetic
vector tubes are generalized to plane flows of a finitely conducting fluid in an orthogonal magnetic field. The Helmholtz
and Kelvin vorticity conservation theorems are generalized for plane motion of a viscous conducting fluid in an orthogonal
magnetic field and the Bernoulli integral is derived. The Bernoulli integral is also generalized for plane motion of viscous
ideally conducting fluid in a longitudinal magnetic field.
Translated from Nelineinye Dinamicheskie Sistemy: Kachestvennyi Analiz i Upravlenie — Sbornik Trudov, No. 2, pp. 46–49, 1994. 相似文献
8.
P. M. Akhmet’ev O. V. Kunakovskaya V. A. Kutvitskii 《Theoretical and Mathematical Physics》2009,158(1):125-134
We prove that the current helicity integral for a thin magnetic tube is directly proportional to the twist Tw of field lines, which appears in the Călugărianu formula as a summand. Using this approach, we analyze the law of the variation
of magnetic helicity in a conducting medium with a nonzero magnetic diffusion coefficient and also the equation of the phase
transition of the magnetic field under early universe conditions.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 158, No. 1, pp. 150–160, January, 2009. 相似文献
9.
V. R. Khalilov 《Theoretical and Mathematical Physics》2005,145(1):1462-1473
We study the influence of a magnetic field on the electroweak processes of nucleon decay in a degenerate ideal gas of neutrons,
protons, and electrons situated in an external superstrong constant and homogeneous magnetic field with effects due to the
interaction of nucleon anomalous magnetic moments with the magnetic field taken into account. For different values of the
chemical potentials of degenerate fermions, we obtain expressions for probabilities of electroweak processes, which are assumed
to be responsible for the chemical equilibrium in the central domain of a neutron star with a frozen superstrong magnetic
field. We show that the difference between the neutron decay probabilities in the presence of a magnetic field B ≪ 1017 G and without this field is completely determined by changing the phase volume of electron states. We discuss the process
of proton decay into a neutron, positron, and neutrino. This process is energetically allowed only when the interaction of
nucleon anomalous magnetic moments with a superstrong magnetic field is taken into account.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 145, No. 1, pp. 108–122, October, 2005. 相似文献
10.
V. R. Khalilov 《Theoretical and Mathematical Physics》2000,125(1):1413-1430
The Green's function of the Dirac equation with an external stationary homogeneous magnetic field in the (2+1)-dimensional
quantum electrodynamics (QED
2+1) with a nonzero fermion density is constructed. An expression for the polarization operator in an external stationary homogenous
magnetic field with a nonzero chemical potential is derived in the one-loopQED
2+1 approximation. The contribution of the induced Chern—Simons term to the polarization operator and the effective Lagrangian
for the fermion density corresponding to the occupation of n relativistic Landau levels in an external magnetic field are
calculated. An expression of the induced Chern—Simons term in a magnetic field for the case of a finite temperature and a
nonzero chemical potential is obtained.
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 125, No. 1, pp. 132–151, October, 2000. 相似文献
11.
D. S. Filippychev 《Computational Mathematics and Modeling》1997,8(2):135-143
We consider the behavior of a plasma bounded in the longitudinal direction by absorbing walls. The model contains charged
particles (electrons and ions) moving in the direction of an external magnetic field with two velocity components: longitudinal
and transverse. The charged particles are created in pairs by a distributed source. The working model is based on the electrostatic
“particles in a cell” method augmented by Emmert's model for a volume source and a model of binary Coulomb particle collisions
using the Monte Carlo method. Calculation results are reported for a model with electron-ion collisions and for a collisionless
plasma model.
Translated from Chislennye Metody v Matematicheskoi Fizike, Published by Moscow University, Moscow, 1996, pp. 100–109. 相似文献
12.
The E ∼ j relation of an HTSC slab is solved strictly within the Bean’s model in two different situations where the system
does and does not reach equilibrium state under the magnetic relaxation respectively, with both forward and backward hopping
taken into consideration (the backward hopping means the hopping from the barriers with low energy to high ones). Our results
suggest and rigorously prove that the In E ∼ In j curves show only positive curvature on the side of slab where the directions
of current-created field and the applied field are the same, while they show both positive and negative curvatures at a certain
field range on the other side where the directions are opposite. The relationship of the positive and negative curvatures
with the critical current, applied field and temperature is also discussed. 相似文献
13.
The interaction of two charges moving in ℝ3 in a magnetic field B can be formulated as a Hamiltonian system with six degrees of freedom. Assuming that the magnetic field is uniform and the
interaction potential has rotation symmetry, we reduce this system to one with three degrees of freedom. For special values
of the conserved quantities, choices of parameters or restriction to the coplanar case, we obtain systems with two degrees
of freedom. Specialising to the case of Coulomb interaction, these reductions enable us to obtain many qualitative features
of the dynamics. For charges of the same sign, the gyrohelices either “bounce-back”, “pass-through”, or exceptionally converge
to coplanar solutions. For charges of opposite signs, we decompose the state space into “free” and “trapped” parts with transitions
only when the particles are coplanar. A scattering map is defined for those trajectories that come from and go to infinite
separation along the field direction. It determines the asymptotic parallel velocities, guiding centre field lines, magnetic
moments and gyrophases for large positive time from those for large negative time. In regimes where gyrophase averaging is
appropriate, the scattering map has a simple form, conserving the magnetic moments and parallel kinetic energies (in a frame
moving along the field with the centre of mass) and rotating or translating the guiding centre field lines. When the gyrofrequencies
are in low-order resonance, however, gyrophase averaging is not justified and transfer of perpendicular kinetic energy is
shown to occur. In the extreme case of equal gyrofrequencies, an additional integral helps us to analyse further and prove
that there is typically also transfer between perpendicular and parallel kinetic energy.
相似文献
14.
The conducting liquid interface is found to undulate in an alternating magnetic field. It was shown earlier that ifM =B
0
2/μηω, B0, ω, μ andη being the amplitude (complex) of the alternating longitudinal magnetic field imposed at the interface, the angular frequency
of the field, the magnetic permeability and the viscosity respectively, and ifM
c was the critical value ofM then the planar layer was stable or unstable according asM < M
c orM > M
c. In this paper we have determined the stability criterion when in addition to the alternating longitudinal field there acts
a uniform field in the same direction. After comparing our results with those obtained earlier, in the absence of the uniform
field, we find that the additional uniform field has a significant destabilizing effect. 相似文献
15.
B. L. Ioffe 《Theoretical and Mathematical Physics》2012,170(2):132-138
We demonstrate that chirality-violating condensates in massless QCD arise entirely from zero-mode solutions of the Dirac equation
in arbitrary gluon fields. We propose a model in which the zero-mode solutions are the ones for quarks moving in the instanton
field and calculate the quark condensate magnetic susceptibilities χ of dimension three and κ and ξ of dimension five based
on this model. The good correspondence of the values of χ, κ, and ξ obtained using this approach with the values found from
the hadronic spectrum is a serious argument that instantons are the only source of chirality-violating condensates in QCD.
We discuss the temperature dependence of the quark condensate and show that the phase transition corresponding to the temperature
dependence α(T) of the quark condensate as an order parameter is a crossover-type transition. 相似文献
16.
A semi-classical quantum theory of the cyclotron radiation of the nonrelativistic thermal electrons in a very strong magnetic
field is presented. The basic formulae of the absorption coefficient of cyclotron resonancek
vand the absorption (scattering) cross-section of cyclotron resonance σ
v
have been derived under the quadrupole approximation. σ
v
is an important quantity in the study of the “magnetic inverse-Compton scattering”. It is shown that σ
v
is greatly larger than the Thomson cross-sectron σT, which is important in discussing the magnetic inverse-Compton scattering of the relativistic electrons in a very strong
magnetic field.
Project supported by the National Natural Science Foundation of China and the Climbing Plan. 相似文献
17.
Consider a compact manifold M with boundary ∂
M endowed with a Riemannian metric g and a magnetic field Ω. Given a point and direction of entry at the boundary, the scattering relation Σ determines the point
and direction of exit of a particle of unit charge, mass, and energy. In this paper we show that a magnetic system (M,∂
M,g,Ω) that is known to be real-analytic and that satisfies some mild restrictions on conjugate points is uniquely determined
up to a natural equivalence by Σ. In the case that the magnetic field Ω is taken to be zero, this gives a new rigidity result
in Riemannian geometry that is more general than related results in the literature. 相似文献
18.
We study the slow singular limit for planar anharmonic oscillatory motion of a charged particle under the influence of a perpendicular
magnetic field when the mass of the particle goes to zero. This model has been used by the authors as a toy model for exploring
variational high-order approximations to the slow dynamics in rotating fluids. In this paper, we address the long time validity
of the slow limit equations in the simplest nontrivial case. We show that the first-order reduced model remains O(ε) accurate
over a long 1/ε timescale. The proof is elementary, but involves subtle estimates on the nonautonomous linearized dynamics. 相似文献
19.
Frédéric Klopp 《Mathematische Annalen》2010,347(3):675-687
Consider Γ, a non-degenerate lattice in
\mathbb R2{{\mathbb R}^2} and a constant magnetic field B with a flux though a cell of Γ that is a rational multiple of 2π. We prove that for a generic Γ-periodic potential V, the spectrum of the Landau Hamiltonian with magnetic field B and periodic potential V is purely absolutely continuous. 相似文献
20.
We investigate the magnetohydrodynamic (MHD) process in thin accretion disks. The relevant momentum as well as magnetic reduction
equations in the thin disk approximation are included. On the basis of these equations, we examine numerically the stationary
structures, including distributions of the surface mass density, temperature and flow velocities of a disk around a young
stellar object (YSO). The numerical results are as follows: (i) There should be an upper limit to the magnitude of magnetic
field, such an upper limit corresponds to the equipartition field. For relevant magnitude of magnetic field of the disk’s
interior the disk remains approximately Keplerian. (ii) The distribution of effective temperature T(r) is a smoothly decreasing
function of radius with power index γ -1/2, corresponding to the observed radiation flux density, provided that the magnetic
field is suitably chosen. 相似文献