67 research outputs found
Induced vacuum condensates in the background of a singular magnetic vortex in 2+1-dimensional space-time
We show that the vacuum of the quantized massless spinor field in
2+1-dimensional space-time is polarized in the presence of a singular magnetic
vortex. Depending on the choice of the boundary condition at the location of
the vortex, either chiral symmetry or parity is broken; the formation of the
appropriate vacuum condensates is comprehensively studied. In addition, we find
that current, energy and other quantum numbers are induced in the vacuum.Comment: LaTeX2e, 27 page
Induced vacuum energy-momentum tensor in the background of a d-2 - brane in d+1 - dimensional space-time
Charged scalar field is quantized in the background of a static d-2 - brane
which is a core of the magnetic flux lines in flat d+1 - dimensional
space-time. We find that vector potential of the magnetic core induces the
energy-momentum tensor in the vacuum. The tensor components are periodic
functions of the brane flux and holomorphic functions of space dimension. The
dependence on the distance from the brane and on the coupling to the space-time
curvature scalar is comprehensively analysed.Comment: 32 pages, 3 figures, journal version, some references adde
Induced vacuum energy-momentum tensor in the background of a cosmic string
A massive scalar field is quantized in the background of a cosmic string
which is generalized to a static flux-carrying codimension-2 brane in the
locally flat multidimensional space-time. We find that the finite
energy-momentum tensor is induced in the vacuum. The dependence of the tensor
components on the brane flux and tension, as well as on the coupling to the
space-time curvature scalar, is comprehensively analyzed. The tensor components
are holomorphic functions of space dimension, decreasing exponentially with the
distance from the brane. The case of the massless quantized scalar field is
also considered, and the relevance of Bernoulli's polynomials of even order for
this case is discussed.Comment: 21 pages, 2 figures; introductory part extended, references adde
The Nonlinear Permittivity Including Non-Abelian Self-interaction of Plasmons in Quark-Gluon Plasma
By decomposing the distribution functions and color field to regular and
fluctuation parts, the solution of the semi-classical kinetic equations of
quark-gluon plasma is analyzed. Through expanding the kinetic equations of the
fluctuation parts to third order, the nonlinear permittivity including the
self-interaction of gauge field is obtained and a rough numerical estimate is
given out for the important \vk =0 modes of the pure gluon plasma.Comment: 7 pages, shortened version accepted by Chin.Phys.Let
Monte Carlo Eikonal Scattering
Monte Carlo evaluation is used to calculate heavy-ion elastic scattering
including the center-of-mass correction and the Coulomb interaction.Angular
distributions are presented for a number of nuclear pairs over a wide energy
range using nucleon-nucleon scattering parameters taken from phase-shift
analyses and densities from independent sources. A technique for the efficient
expansion of the Glauber amplitude in partial waves is developed
Dirac fields in the background of a magnetic flux string and spectral boundary conditions
We study the problem of a Dirac field in the background of an Aharonov-Bohm
flux string. We exclude the origin by imposing spectral boundary conditions at
a finite radius then shrinked to zero. Thus, we obtain a behaviour of
eigenfunctions which is compatible with the self-adjointness of the radial
Hamiltonian and the invariance under integer translations of the reduced flux.
After confining the theory to a finite region, we check the consistency with
the index theorem, and evaluate its vacuum fermionic number and Casimir energy.Comment: 9 pages, 1 figure Two references added To be published in
International Journal of Modern Physics
The Origin of Magnetic Fields in Galaxies
Microgauss magnetic fields are observed in all galaxies at low and high
redshifts. The origin of these intense magnetic fields is a challenging
question in astrophysics. We show here that the natural plasma fluctuations in
the primordial universe (assumed to be random), predicted by the
Fluctuation-Dissipation-Theorem, predicts fields over kpc regions in galaxies.
If the dipole magnetic fields predicted by the
Fluctuation-Dissipation-Theorem are not completely random, microgauss fields
over regions kpc are easily obtained. The model is thus a strong
candidate for resolving the problem of the origin of magnetic fields in
years in high redshift galaxies.Comment: 10 pages, 3 figure
Spherical model of the Stark effect in external scalar and vector fields
The Bohr-Sommerfeld quantization rule and the Gamow formula for the width of
quasistationary level are generalized by taking into account the relativistic
effects, spin and Lorentz structure of interaction potentials. The relativistic
quasi-classical theory of ionization of the Coulomb system (V_{Coul}=-\xi/r) by
radial-constant long-range scalar (S_{l.r.}=(1-\lambda)(\sigma r+V_0)) and
vector (V_{l.r.}=\lambda(\sigma r+V_0)) fields is constructed. In the limiting
cases the approximated analytical expressions for the position E_r and width
\Gamma of below-barrier resonances are obtained. The strong dependence of the
width \Gamma of below-barrier resonances on both the bound level energy and the
mixing constant \lambda is detected. The simple analytical formulae for
asymptotic coefficients of the Dirac radial wave functions at zero and infinity
are also obtained.Comment: 25 pages, 4 figures. Submitted to Int. J. Mod. Phys.
The ground state energy of a spinor field in the background of a finite radius flux tube
We develop a formalism for the calculation of the ground state energy of a
spinor field in the background of a cylindrically symmetric magnetic field. The
energy is expressed in terms of the Jost function of the associated scattering
problem. Uniform asymptotic expansions needed are obtained from the
Lippmann-Schwinger equation. The general results derived are applied to the
background of a finite radius flux tube with a homogeneous magnetic field
inside and the ground state energy is calculated numerically as a function of
the radius and the flux. It turns out to be negative, remaining smaller by a
factor of than the classical energy of the background except for very
small values of the radius which are outside the range of applicability of QED.Comment: 25 pages, 3 figure
Casimir energy of massive MIT fermions in a Bohm-Aharonov background
We study the effect of a background flux string on the vacuum energy of
massive Dirac fermions in 2+1 dimensions confined to a finite spatial region
through MIT boundary conditions. We treat two admissible self-adjoint
extensions of the Hamiltonian and compare the results. In particular, for one
of these extensions, the Casimir energy turns out to be discontinuous at
integer values of the flux.Comment: 16 pages, 3 figure
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