610 research outputs found
Improved assay method for activity of thyroid peroxidase-catalysed coupling of iodotyrosine residues of thyroglobulin utilizing h.p.l.c. for analysis of iodothyronines
Partition Function for (2+1)-Dimensional Einstein Gravity
Taking (2+1)-dimensional pure Einstein gravity for arbitrary genus as a
model, we investigate the relation between the partition function formally
defined on the entire phase space and the one written in terms of the reduced
phase space. In particular the case of is analyzed in detail.
By a suitable gauge-fixing, the partition function basically reduces to
the partition function defined for the reduced system, whose dynamical
variables are . [The 's are the Teichm\"uller
parameters, and the 's are their conjugate momenta.]
As for the case of , we find out that is also related with another
reduced form, whose dynamical variables are and .
[Here is a conjugate momentum to 2-volume .] A nontrivial factor
appears in the measure in terms of this type of reduced form. The factor turns
out to be a Faddeev-Popov determinant coming from the time-reparameterization
invariance inherent in this type of formulation. Thus the relation between two
reduced forms becomes transparent even in the context of quantum theory.
Furthermore for , a factor coming from the zero-modes of a differential
operator can appear in the path-integral measure in the reduced
representation of . It depends on the path-integral domain for the shift
vector in : If it is defined to include , the nontrivial factor
does not appear. On the other hand, if the integral domain is defined to
exclude , the factor appears in the measure. This factor can depend
on the dynamical variables, typically as a function of , and can influence
the semiclassical dynamics of the (2+1)-dimensional spacetime.
These results shall be significant from the viewpoint of quantum gravity.Comment: 21 pages. To appear in Physical Review D. The discussion on the
path-integral domain for the shift vector has been adde
Classical and quantum wormholes in a flat -decaying cosmology
We study the classical and quantum wormholes for a flat {\it Euclidean}
Friedmann-Robertson-Walker metric with a perfect fluid including an ordinary
matter source plus a source playing the role of dark energy (decaying
cosmological term). It is shown that classical wormholes exist for this model
and the quantum version of such wormholes are consistent with the Hawking-Page
conjecture for quantum wormholes as solutions of the Wheeler-DeWitt equation.Comment: 8 pages, 4 figures, accepted for publication in IJT
Poincar\'{e} gauge theory of gravity
A Poincar\'{e} gauge theory of (2+1)-dimensional gravity is developed.
Fundamental gravitational field variables are dreibein fields and Lorentz gauge
potentials, and the theory is underlain with the Riemann-Cartan space-time. The
most general gravitational Lagrangian density, which is at most quadratic in
curvature and torsion tensors and invariant under local Lorentz transformations
and under general coordinate transformations, is given. Gravitational field
equations are studied in detail, and solutions of the equations for weak
gravitational fields are examined for the case with a static, \lq \lq spin"less
point like source. We find, among other things, the following: (1)Solutions of
the vacuum Einstein equation satisfy gravitational field equations in the
vacuum in this theory. (2)For a class of the parameters in the gravitational
Lagrangian density, the torsion is \lq \lq frozen" at the place where \lq \lq
spin" density of the source field is not vanishing. In this case, the field
equation actually agrees with the Einstein equation, when the source field is
\lq \lq spin"less. (3)A teleparallel theory developed in a previous paper is
\lq \lq included as a solution" in a limiting case. (4)A Newtonian limit is
obtainable, if the parameters in the Lagrangian density satisfy certain
conditions.Comment: 27pages, RevTeX, OCU-PHYS-15
Microphysical Approach to Nonequilibrium Dynamics of Quantum Fields
We examine the nonequilibrium dynamics of a self-interacting
scalar field theory. Using a real time formulation of finite temperature field
theory we derive, up to two loops and , the effective equation of
motion describing the approach to equilibrium. We present a detailed analysis
of the approximations used in order to obtain a Langevin-like equation of
motion, in which the noise and dissipation terms associated with quantum
fluctuations obey a fluctuation-dissipation relation. We show that, in general,
the noise is colored (time-dependent) and multiplicative (couples nonlinearly
to the field), even though it is still Gaussian distributed. The noise becomes
white in the infinite temperature limit. We also address the effect of
couplings to other fields, which we assume play the r\^ole of the thermal bath,
in the effective equation of motion for . In particular, we obtain the
fluctuation and noise terms due to a quadratic coupling to another scalar
field.Comment: 30 pages, LaTex (uses RevTex 3.0), DART-HEP-93/0
Negative modes in the four-dimensional stringy wormholes
We study the Giddings-Strominger wormholes in string theories. We found
negative modes among O(4)-symmetric fluctuations about the non-singular
wormhole background. Hence the stringy wormhole contribution to the euclidean
functional integral is purely imaginary. This means that the stringy wormhole
is a bounce (not an instanton) and describes the nucleation and growth of
wormholes in the Minkowski spacetime.Comment: 12 pages 2 figures, RevTe
Field-enlarging transformations and chiral theories
A field-enlarging transformation in the chiral electrodynamics is performed.
This introduces an additional gauge symmetry to the model that is unitary and
anomaly-free and allows for comparison of different models discussed in the
literature. The problem of superfluous degrees of freedom and their influence
on quantization is discussed. Several "mysteries" are explained from this point
of view.Comment: 14 pages, LaTeX-file, BI-TP 93/0
Cosmological Sphaleron from Real Tunneling and Its Fate
We show that the cosmological sphaleron of Einstein-Yang-Mills system can be
produced from real tunneling geometries. The sphaleron will tend to roll down
to the vacuum or pure gauge field configuration, when the universe evolves in
the Lorentzian signature region with the sphaleron and the corresponding
hypersurface being the initial data for the Yang-Mills field and the universe,
respectively. However, we can also show that the sphaleron, although unstable,
can be regarded as a pseudo-stable solution because its lifetime is even much
greater than those of the universe.Comment: 20 pages, LaTex, article 12pt style, TIT/HEP-242/COSMO-3
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