3,738 research outputs found
Electromagnetism and multiple-valued loop-dependent wave functionals
We quantize the Maxwell theory in the presence of a electric charge in a
"dual" Loop Representation, i.e. a geometric representation of magnetic
Faraday's lines. It is found that the theory can be seen as a theory without
sources, except by the fact that the wave functional becomes multivalued. This
can be seen as the dual counterpart of what occurs in Maxwell theory with a
magnetic pole, when it is quantized in the ordinary Loop Representation. The
multivaluedness can be seen as a result of the multiply-connectedness of the
configuration space of the quantum theory.Comment: 5 page
P.A.M. Dirac and the Discovery of Quantum Mechanics
Dirac's contributions to the discovery of non-relativistic quantum mechanics
and quantum electrodynamics, prior to his discovery of the relativistic wave
equation, are described
Extreme Fire as a Management Tool to Combat Regime Shifts in the Range of the Endangered American Burying Beetle
This study is focused on the population of federally-endangered American burying beetles in south-central Nebraska. It is focused on changes in land cover over time and at several levels of spatial scale, and how management efforts are impacting both the beetle and a changing landscape. Our findings are applicable to a large portion of the Great Plains, which is undergoing the same shift from grassland to woodland, and to areas where the beetle is still found
Geometric phases, gauge symmetries and ray representation
The conventional formulation of the non-adiabatic (Aharonov-Anandan) phase is
based on the equivalence class which is not
a symmetry of the Schr\"{o}dinger equation. This equivalence class when
understood as defining generalized rays in the Hilbert space is not generally
consistent with the superposition principle in interference and polarization
phenomena. The hidden local gauge symmetry, which arises from the arbitrariness
of the choice of coordinates in the functional space, is then proposed as a
basic gauge symmetry in the non-adiabatic phase. This re-formulation reproduces
all the successful aspects of the non-adiabatic phase in a manner manifestly
consistent with the conventional notion of rays and the superposition
principle. The hidden local symmetry is thus identified as the natural origin
of the gauge symmetry in both of the adiabatic and non-adiabatic phases in the
absence of gauge fields, and it allows a unified treatment of all the geometric
phases. The non-adiabatic phase may well be regarded as a special case of the
adiabatic phase in this re-formulation, contrary to the customary understanding
of the adiabatic phase as a special case of the non-adiabatic phase. Some
explicit examples of geometric phases are discussed to illustrate this
re-formulation.Comment: 30 pages. Some clarifying sentences have been added in abstract and
in the body of the paper. A new additional reference and some typos have been
corrected. To appear in Int. J. Mod. Phys.
Application of the canonical quantization of systems with curved phase space to the EMDA theory
The canonical quantization of dynamical systems with curved phase space
introduced by I.A. Batalin, E.S. Fradkin and T.E. Fradkina is applied to the
four-dimensional Einstein-Maxwell Dilaton-Axion theory. The spherically
symmetric case with radial fields is considered. The Lagrangian density of the
theory in the Einstein frame is written as an expression with first order in
time derivatives of the fields. The phase space is curved due to the nontrivial
interaction of the dilaton with the axion and the electromagnetic fields.Comment: 23 pages in late
Non-Abelian Gauged Chiral Boson with a Generalized Faddevian Regularization
We consider non-Abelian gauged version of chiral boson with a generalized
Faddeevian regularization. It is a second class constrained theory. We quantize
the theory and analyze the phase space. It is shown that in spite of the lack
of manifest Lorentz invariance in the action, it has a consistent and Poincare'
invariant phase space structure.Comment: 10 pages latex fil
Effective Constraints for Relativistic Quantum Systems
Determining the physical Hilbert space is often considered the most difficult
but crucial part of completing the quantization of a constrained system. In
such a situation it can be more economical to use effective constraint methods,
which are extended here to relativistic systems as they arise for instance in
quantum cosmology. By side-stepping explicit constructions of states, such
tools allow one to arrive much more feasibly at results for physical
observables at least in semiclassical regimes. Several questions discussed
recently regarding effective equations and state properties in quantum
cosmology, including the spreading of states and quantum back-reaction, are
addressed by the examples studied here.Comment: 27 pages, 2 figures; v2: new appendix comparing effective constraints
and physical coherent states by an exampl
The Static Quantum Multiverse
We consider the multiverse in the intrinsically quantum mechanical framework
recently proposed in Refs. [1,2]. By requiring that the principles of quantum
mechanics are universally valid and that physical predictions do not depend on
the reference frame one chooses to describe the multiverse, we find that the
multiverse state must be static---in particular, the multiverse does not have a
beginning or end. We argue that, despite its naive appearance, this does not
contradict observation, including the fact that we observe that time flows in a
definite direction. Selecting the multiverse state is ultimately boiled down to
finding normalizable solutions to certain zero-eigenvalue equations, analogous
to the case of the hydrogen atom. Unambiguous physical predictions would then
follow, according to the rules of quantum mechanics.Comment: 27 pages, 2 figures; a typo in the abstract correcte
Chiral QED in Terms of Chiral Boson with a Generalized Fadeevian Regularization
Chiral QED with a generalized Fadeevian regularization is considered.
Imposing a chiral constraint a gauged version of Floranini-Jackiw lagrangian is
constructed. The imposition of the chiral constarint has spoiled t he
manifestly Lorentz covariance of the theory. The phase space structure for this
theory has been det ermined. It is found that spectrum changes drastically but
it is Lorentz invariant. Chiral fermion di sappears from the spectra and the
photon anquire mass as well. Poincare algebra has been calculated to show
physicial Lorentz invariance explicitely.Comment: 11 page
On the Implementation of Constraints through Projection Operators
Quantum constraints of the type Q \psi = 0 can be straightforwardly
implemented in cases where Q is a self-adjoint operator for which zero is an
eigenvalue. In that case, the physical Hilbert space is obtained by projecting
onto the kernel of Q, i.e. H_phys = ker(Q) = ker(Q*). It is, however,
nontrivial to identify and project onto H_phys when zero is not in the point
spectrum but instead is in the continuous spectrum of Q, because in this case
the kernel of Q is empty.
Here, we observe that the topology of the underlying Hilbert space can be
harmlessly modified in the direction perpendicular to the constraint surface in
such a way that Q becomes non-self-adjoint. This procedure then allows us to
conveniently obtain H_phys as the proper Hilbert subspace H_phys = ker(Q*), on
which one can project as usual. In the simplest case, the necessary change of
topology amounts to passing from an L^2 Hilbert space to a Sobolev space.Comment: 22 pages, LaTe
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