36 research outputs found
Dynamics as Shadow of Phase Space Geometry
Starting with the generally well accepted opinion that quantizing an
arbitrary Hamiltonian system involves picking out some additional structure on
the classical phase space (the {\sl shadow} of quantum mechanics in the
classical theory), we describe classical as well as quantum dynamics as a
purely geometrical effect by introducing a {\sl phase space metric structure}.
This produces an modification of the classical equations of
motion reducing at the same time the quantization of an arbitrary Hamiltonian
system to standard procedures. Our analysis is carried out in analogy with the
adiabatic motion of a charged particle in a curved background (the additional
metric structure) under the influence of a universal magnetic field (the
classical symplectic structure). This allows one to picture dynamics in an
unusual way, and reveals a dynamical mechanism that produces the selection of
the right set of physical quantum states.Comment: LaTeX (epsfig macros), 30 pages, 1 figur
A Dynamical Mechanism for the Selection of Physical States in `Geometric Quantization Schemes'
Geometric quantization procedures go usually through an extension of the
original theory (pre-quantization) and a subsequent reduction (selection of the
physical states). In this context we describe a full geometrical mechanism
which provides dynamically the desired reduction.Comment: 6 page
Elementary Particles and Spin Representations
We emphasize that the group-theoretical considerations leading to SO(10)
unification of electro-weak and strong matter field components naturally extend
to space-time components, providing a truly unified description of all
generation degrees of freedoms in terms of a single chiral spin representation
of one of the groups SO(13,1), SO(9,5), SO(7,7) or SO(3,11). The realization of
these groups as higher dimensional space-time symmetries produces unification
of all fundamental fermions is a single space-time spinor.Comment: 4 page
Adiabatic Motion of a Quantum Particle in a Two-Dimensional Magnetic Field
The adiabatic motion of a charged, spinning, quantum particle in a two -
dimensional magnetic field is studied. A suitable set of operators generalizing
the cinematical momenta and the guiding center operators of a particle moving
in a homogeneous magnetic field is constructed. This allows us to separate the
two degrees of freedom of the system into a {\sl fast} and a {\sl slow} one, in
the classical limit, the rapid rotation of the particle around the guiding
center and the slow guiding center drift. In terms of these operators the
Hamiltonian of the system rewrites as a power series in the magnetic length
\lb=\sqrt{\hbar c\over eB} and the fast and slow dynamics separates. The
effective guiding center Hamiltonian is obtained to the second order in the
adiabatic parameter \lb and reproduces correctly the classical limit.Comment: 17 pages, LaTe
A Complete Perturbative Expansion for Constrained Quantum Dynamics
A complete perturbative expansion for the Hamiltonian describing the motion
of a quantomechanical system constrained to move on an arbitrary submanifold of
its configuration space is obtained.Comment: 18 pages, LaTe
Torsion-induced persistent current in a twisted quantum ring
We describe the effects of geometric torsion on the coherent motion of
electrons along a thin twisted quantum ring. The geometric torsion inherent in
the quantum ring triggers a quantum phase shift in the electrons' eigenstates,
thereby resulting in a torsion-induced persistent current that flows along the
twisted quantum ring. The physical conditions required for detecting the
current flow are discussed.Comment: 9 pages, 3 figure
All order covariant tubular expansion
We consider tubular neighborhood of an arbitrary submanifold embedded in a
(pseudo-)Riemannian manifold. This can be described by Fermi normal coordinates
(FNC) satisfying certain conditions as described by Florides and Synge in
\cite{FS}. By generalizing the work of Muller {\it et al} in \cite{muller} on
Riemann normal coordinate expansion, we derive all order FNC expansion of
vielbein in this neighborhood with closed form expressions for the curvature
expansion coefficients. Our result is shown to be consistent with certain
integral theorem for the metric proved in \cite{FS}.Comment: 27 pages. Corrected an error in a class of coefficients resulting
from a typo. Integral theorem and all other results remain unchange