1,345,064 research outputs found
Ground state of antiferromagnetic ordering in fullerene molecule
Theoretical study of mutual orientation of fullerene molecule atom
spins is presented in this work. Spin-spin interaction was described by
Habbard's model. Existence of antiferromagnetic sturcture of spin sub-system in
ground state is found
A Possible Origin of Dark Matter, Dark Energy, and Particle-Antiparticle Asymmetry
In this paper we present a possible origin of dark matter and dark energy
from a solution of the Einstein's equation to a primordial universe, which was
presented in a previous paper. We also analyze the Dirac's equation in this
primordial universe and present the possible origin of the
particle-antiparticle asymmetry. We also present ghost primordial particles as
candidates to some quantum vacuum contituents.Comment: 19 pages,no figure
Effect of nuclear quadrupole moment on parity nonconservation in atoms
Nuclei with spin have a weak quadrupole moment which leads to
tensor contribution to the parity non-conserving interaction between nuclei and
electrons. We calculate this contribution for Yb, Fr and Ra and found
it to be small. In contrast, in many lanthanides (e.g., Nd, Gd, Dy, Ho, Er, Pr,
Sm) and Ra close levels of opposite parity lead to strong enhancement of the
effect making it sufficiently large to be measured. Another possibility is to
measure the PNC transitions between the hyperfine components of the ground
state of Bi. Since nuclear weak charge is dominated by neutrons this opens a
way of measuring quadrupole moments of neutron distribution in nuclei.Comment: 9 pages, 1 figur
Resonance Type Instabilities in the Gaseous Disks of the Flat Galaxies II. The stability of solitary vortex sheet
Linear stability analysis of the axisymmetric interface of velocity and
density discontinuity in rotating gaseous disk has been performed numerically
and analytically. Physical mechanisms leading to development of centrifugal and
Kelvin-Helmholtz instability at the kink has been analysed in detail. In the
incompressible limit it has been shown in the first time such areas in the
parameter space that Kelvin-Helmholtz instability is stabilized by the density
kink. This effect is caused by both specifical angular momentum conservation
and buoyancy. The possibility of application of obtained results to the
stability analysis of the gaseous disks of the real flat galaxies is discussed.Comment: Plain TeX, 10 pages, 6 postscript figures, uses epsf.te
Topics in Non-Riemannian Geometry
In this paper, we present some new results on non-Riemannian geometry, more
specifically, asymmetric connections and Weyl's geometry. For asymmetric
connections, we show that a projective change in the symmetric part generates a
vector field that its not arbitrary, as usually presented, but rather, the
gradient of a non-arbitrary scalar function. We use normal coordinates for the
symmetric part of asymmetric connections as well as for the Weyl's geometry.
This has a direct impact on asymmetric conections, although normal frames are
usual in antisymmetic connections, unlike normal coordinates. In this symmetric
part of asymmetric connections, the vector fields obeys a well-known partial
differential equantion, whereas in Weyl's geometry, gauge vector fields obey an
equation that we believe is presented for the first time in this paper. We
deduce the exact solution of each of these vector fields as the gradient of a
scalar function. For both asymmetric and Weyl's symmetric connections, the
respective scalar functions obey respective scalar partial differential
equations. As a consequence, Weyl's geometry is a conformal differential
geometry and is associated with asymmetric geometry by a projective change. We
also show that a metric tensor naturally appears in asymmetric geometry and is
not introduced via a postulate, as is usually done. In Weyl's geometry, the
eletromagnetic gauge is the gradient of a non-arbitrary scalar function and
eletromagnetic fields are null. Despide the origin in Weyl's differential
geometry, the use of the eletromagnetic gauge is correct in Lagrangean and
Hamiltonian formulations of field theories.Comment: 11 pages, no figures, last versio
Effect of atomic electric quadrupole moment on positron binding
Effect of the electric quadrupole moment, , is studied for positron-atom
bound systems. It is demonstrated that for a.u. the electric quadrupole
potential is sufficiently strong to bind positron (or electron) even in the
absence of the dipole polarization potential. Such large values of are not
known for atomic ground states, however, they exist in molecules and excited
atoms. In the state of beryllium, the quadrupole contribution
makes difference between stable bound state and decay to Be ion and
positronium. In a majority of atoms the quadrupole contribution is small and
can be neglected.Comment: 5 pages, 1 figur
The motion of a charged particle in Kalusa-Klein manifolds
In this paper we use Jacobi fields to describe the motion of a charged
particle in the classical gravitational, electromagnetic, and Yang-Mills
fields.Comment: 8 pages, Mikte
Atoms which can bind positrons
Calculations of the positron binding energies to all atoms in the periodic
table are presented and atoms where the positron-atom binding actually exists
are identified. The results of these calculations and accurate calculations of
other authors (which existed for several atoms only) are used to evaluate
recommended values of the positron binding energies to the ground states of
atoms. We also present the recommended energies of the positron excited bound
levels and resonances (due to the binding of positron to excited states of
atoms) which can not emit positronium and have relatively narrow widths. Such
resonances in positron annihilation and scattering may be used to measure the
positron binding energy.Comment: 19 pages, 10 tables, 2 figures, submitted to Phys. Rev. A. arXiv
admin note: text overlap with arXiv:1204.6577,improved tex
Physical Principles Based on Geometric Properties
In this paper we present some results obtained in a previous paper about the
Cartan's approach to Riemannian normal coordinates and our conformal
transformations among pseudo-Riemannian manifolds. We also review the classical
and the quantum angular momenta of a particle obtained as a consequence of
geometry, without postulates. We present four classical principles, identifed
as new results obtained from geometry. One of them has properties similar
Heisemberg's uncertaintly principle and another has some properties similar to
Bohr's principle. Our geometric result can be considered as a possible starting
point toward a quantum theory without forces.Comment: 25 pages, no figure
Conformal Form of Pseudo-Riemannian Metrics by Normal Coordinate Transformations II
In this paper, we have reintroduced a new approach to conformal geometry
developed and presented in two previous papers, in which we show that all
n-dimensional pseudo-Riemannian metrics are conformal to a flat n-dimensional
manifold as well as an n-dimensional manifold of constant curvature when
Riemannian normal coordinates are well-behaved in the origin and in their
neighborhood. This was based on an approach developed by French mathematician
Elie Cartan. As a consequence of geometry, we have reintroduced the classical
and quantum angular momenta of a particle and present new interpretations. We
also show that all n-dimensional pseudo-Riemannian metrics can be embedded in a
hyper-cone of a flat n+2-dimensional manifold.Comment: 33 pages,no figures. Paper of a talk given at the 14th International
Conference on Geometry, Integrability and Quantization (Varna, Bulgaria, June
2012
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