6,161 research outputs found
A Chiral Spin Theory in the Framework of an Invariant Evolution Parameter Formalism
We present a formulation for the construction of first order equations which
describe particles with spin, in the context of a manifestly covariant
relativistic theory governed by an invariant evolution parameter; one obtains a
consistent quantized formalism dealing with off-shell particles with spin. Our
basic requirement is that the second order equation in the theory is of the
Schr\"{o}dinger-Stueckelberg type, which exhibits features of both the
Klein-Gordon and Schr\"{o}dinger equations. This requirement restricts the
structure of the first order equation, in particular, to a chiral form. One
thus obtains, in a natural way, a theory of chiral form for massive particles,
which may contain both left and right chiralities, or just one of them. We
observe that by iterating the first order system, we are able to obtain second
order forms containing the transverse and longitudinal momentum relative to a
time-like vector used to maintain covariance of the theory.
This time-like vector coincides with the one used by Horwitz, Piron, and Reuse
to obtain an invariant positive definite space-time scalar product, which
permits the construction of an induced representation for states of a particle
with spin. We discuss the currents and continuity equations, and show that
these equations of motion and their currents are closely related to the spin
and convection parts of the Gordon decomposition of the Dirac current. The
transverse and longitudinal aspects of the particle are complementary, and can
be treated in a unified manner using a tensor product Hilbert space.
Introducing the electromagnetic field we find an equation which gives rise to
the correct gyromagnetic ratio, and is fully Hermitian under the proposed
scalar product. Finally, we show that the original structure of Dirac'sComment: Latex, 61 pages. Minor revisions. To be published in J. Math. Phy
Gravitational Repulsion within a Black-Hole using the Stueckelberg Quantum Formalism
We wish to study an application of Stueckelberg's relativistic quantum theory
in the framework of general relativity. We study the form of the wave equation
of a massive body in the presence of a Schwarzschild gravitational field. We
treat the mathematical behavior of the wavefunction also around and beyond the
horizon (r=2M). Classically, within the horizon, the time component of the
metric becomes spacelike and distance from the origin singularity becomes
timelike, suggesting an inevitable propagation of all matter within the horizon
to a total collapse at r=0. However, the quantum description of the wave
function provides a different understanding of the behavior of matter within
the horizon. We find that a test particle can almost never be found at the
origin and is more probable to be found at the horizon. Matter outside the
horizon has a very small wave length and therefore interference effects can be
found only on a very small atomic scale. However, within the horizon, matter
becomes totally "tachionic" and is potentially "spread" over all space. Small
location uncertainties on the atomic scale become large around the horizon, and
different mass components of the wave function can therefore interfere on a
stellar scale. This interference phenomenon, where the probability of finding
matter decreases as a function of the distance from the horizon, appears as an
effective gravitational repulsion.Comment: 20 pages, 6 figure
The benthic macrofauna of sludge-affected sediments in the Derwent Estuary, southern Tasmania
The paper reports the findings of an extensive survey of benthic invertebrates from the Derwent estuary in southern Tasmania, sampled during an investigation into the distribution and character of sludge emanating from a pulp and paper factory. In total, 45 invertebrate species were collected, but none was found in the sediment in the river channel between the pulpmill (its effluent outfall) and a site 5 km downstream.
Similarly, other sediments with wood fibre present (measured by loss on ignition) and with very negative redox values were faunistically depauperate and possessed much lower species richness than that anticipated from other studies in Australia. The sediments in shallow areas in the middle part of the estuary had very high densities of invertebrates and had less mechanical wood fibre than sediments in deeper water nearby or other sediments further downstream. These results suggest that smothering by wood fibre, with concomitant toxicological effects of chemical reactions in the sediment, results in the low invertebrate diversities observed. These findings must be tempered by the methodological limitations involved with the selection of sample sites and lack of seasonal data, which have prevented definitive statements from being made about the level of environmental stress being experienced in the lower parts of the estuary
Microcanonical Ensemble and Algebra of Conserved Generators for Generalized Quantum Dynamics
It has recently been shown, by application of statistical mechanical methods
to determine the canonical ensemble governing the equilibrium distribution of
operator initial values, that complex quantum field theory can emerge as a
statistical approximation to an underlying generalized quantum dynamics. This
result was obtained by an argument based on a Ward identity analogous to the
equipartition theorem of classical statistical mechanics. We construct here a
microcanonical ensemble which forms the basis of this canonical ensemble. This
construction enables us to define the microcanonical entropy and free energy of
the field configuration of the equilibrium distribution and to study the
stability of the canonical ensemble. We also study the algebraic structure of
the conserved generators from which the microcanonical and canonical ensembles
are constructed, and the flows they induce on the phase space.Comment: Plain TeX, 18 pages. Corrected report number onl
Optical modeling of agricultural fields and rough-textured rock and mineral surfaces
Review was made of past models for describing the reflectance and/or emittance properties of agricultural/forestry and geological targets in an effort to select the best theoretical models. An extension of the six parameter Allen-Gayle-Richardson model was chosen as the agricultural plant canopy model. The model is used to predict the bidirectional reflectance of a field crop from known laboratory spectra of crop components and approximate plant geometry. The selected geological model is based on Mie theory and radiative transfer equations, and will assess the effect of textural variations of the spectral emittance of natural rock surfaces
Quantum Time and Spatial Localization: An Analysis of the Hegerfeldt Paradox
Two related problems in relativistic quantum mechanics, the apparent
superluminal propagation of initially localized particles and dependence of
spatial localization on the motion of the observer, are analyzed in the context
of Dirac's theory of constraints. A parametrization invariant formulation is
obtained by introducing time and energy operators for the relativistic particle
and then treating the Klein-Gordon equation as a constraint. The standard,
physical Hilbert space is recovered, via integration over proper time, from an
augmented Hilbert space wherein time and energy are dynamical variables. It is
shown that the Newton-Wigner position operator, being in this description a
constant of motion, acts on states in the augmented space. States with strictly
positive energy are non-local in time; consequently, position measurements
receive contributions from states representing the particle's position at many
times. Apparent superluminal propagation is explained by noting that, as the
particle is potentially in the past (or future) of the assumed initial place
and time of localization, it has time to propagate to distant regions without
exceeding the speed of light. An inequality is proven showing the Hegerfeldt
paradox to be completely accounted for by the hypotheses of subluminal
propagation from a set of initial space-time points determined by the quantum
time distribution arising from the positivity of the system's energy. Spatial
localization can nevertheless occur through quantum interference between states
representing the particle at different times. The non-locality of the same
system to a moving observer is due to Lorentz rotation of spatial axes out of
the interference minimum.Comment: This paper is identical to the version appearing in J. Math. Phys.
41; 6093 (Sept. 2000). The published version will be found at
http://ojps.aip.org/jmp/. The paper (40 page PDF file) has been completely
revised since the last posting to this archiv
Equilibrium Relativistic Mass Distribution for Indistinguishable Events
A manifestly covariant relativistic statistical mechanics of the system of
indistinguishable events with motion in space-time parametrized by an
invariant ``historical time'' is considered. The relativistic mass
distribution for such a system is obtained from the equilibrium solution of the
generalized relativistic Boltzmann equation by integration over angular and
hyperbolic angular variables. All the characteristic averages are calculated.
Expressions for the pressure and the density of events are found and the
relativistic equation of state is obtained. The Galilean limit is considered;
the theory is shown to pass over to the usual nonrelativistic statistical
mechanics of indistinguishable particles.Comment: TAUP-2115-9
Towards a Realistic Equation of State of Strongly Interacting Matter
We consider a relativistic strongly interacting Bose gas. The interaction is
manifested in the off-shellness of the equilibrium distribution. The equation
of state that we obtain for such a gas has the properties of a realistic
equation of state of strongly interacting matter, i.e., at low temperature it
agrees with the one suggested by Shuryak for hadronic matter, while at high
temperature it represents the equation of state of an ideal ultrarelativistic
Stefan-Boltzmann gas, implying a phase transition to an effectively weakly
interacting phase.Comment: LaTeX, figures not include
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