1,482 research outputs found
Embedding Brans-Dicke gravity into electroweak theory
We argue that a version of the four dimensional Brans-Dicke theory can be
embedded in the standard flat spacetime electroweak theory. The embedding
involves a change of variables that separates the isospin from the hypercharge
in the electroweak theory.Comment: 4 pages, no figures; replaced to match published versio
Anomaly-Induced Magnetic Screening in 2+1 dimensional QED at Finite Density
We show that in 2+1 dimensional Quantum Electrodynamics an external magnetic
field applied to a finite density of massless fermions is screened, due to a
-dimensional realization of the underlying -dimensional axial anomaly
of the space components of the electric current. This is shown to imply
screening of the magnetic field, i.e., the Meissner effect. We discuss the
physical implications of this result.Comment: 8 pages, DFTT-93-10 [ Eq.(15) and (16) were scrambled in previous
version
Abelian and Non-Abelian Induced Parity Breaking Terms at Finite Temperature
We compute the exact canonically induced parity breaking part of the
effective action for 2+1 massive fermions in particular Abelian and non Abelian
gauge field backgrounds. The method of computation resorts to the chiral
anomaly of the dimensionally reduced theory.Comment: 13 pages, RevTeX, no figure
Induced Parity Breaking Term at Finite Temperature
We compute the exact induced parity-breaking part of the effective action for
2+1 massive fermions in at finite temperature by calculating the
fermion determinant in a particular background. The result confirms that gauge
invariance of the effective action is respected even when large gauge
transformations are considered.Comment: to be published in Physical Review Letters. 5 pages, Revtex, no
figure
On The Finite Temperature Chern-Simons Coefficient
We compute the exact finite temperature effective action in a 0+1-dimensional
field theory containing a topological Chern-Simons term, which has many
features in common with 2+1-dimensional Chern-Simons theories. This exact
result explains the origin and meaning of puzzling temperature dependent
coefficients found in various naive perturbative computations in the higher
dimensional models.Comment: 11 pages LaTeX; no figure
Gauge Invariance, Finite Temperature and Parity Anomaly in D=3
The effective gauge field actions generated by charged fermions in
and can be made invariant under both small and large gauge
transformations at any temperature by suitable regularization of the Dirac
operator determinant, at the price of parity anomalies. We resolve the paradox
that the perturbative expansion is not invariant, as manifested by the
temperature dependence of the induced Chern-Simons term, by showing that large
(unlike small) transformations and hence their Ward identities, are not
perturbative order-preserving. Our results are illustrated through concrete
examples of field configurations.Comment: 4 pages, RevTe
Spin-Charge Separation and the Pauli Electron
The separation between the spin and the charge converts the quantum
mechanical Pauli Hamiltonian into the Hamiltonian of the non-Abelian
Georgi-Glashow model, notorious for its magnetic monopoles and confinement. The
independent spin and charge fluctuations both lead to the Faddeev model,
suggesting the existence of a deep duality structure and indicating that the
fundamental carriers of spin and charge are knotted solitons.Comment: 7 pages; v2: new results added, references update
Derivation of transient relativistic fluid dynamics from the Boltzmann equation
In this work we present a general derivation of relativistic fluid dynamics
from the Boltzmann equation using the method of moments. The main difference
between our approach and the traditional 14-moment approximation is that we
will not close the fluid-dynamical equations of motion by truncating the
expansion of the distribution function. Instead, we keep all terms in the
moment expansion. The reduction of the degrees of freedom is done by
identifying the microscopic time scales of the Boltzmann equation and
considering only the slowest ones. In addition, the equations of motion for the
dissipative quantities are truncated according to a systematic power-counting
scheme in Knudsen and inverse Reynolds number. We conclude that the equations
of motion can be closed in terms of only 14 dynamical variables, as long as we
only keep terms of second order in Knudsen and/or inverse Reynolds number. We
show that, even though the equations of motion are closed in terms of these 14
fields, the transport coefficients carry information about all the moments of
the distribution function. In this way, we can show that the particle-diffusion
and shear-viscosity coefficients agree with the values given by the
Chapman-Enskog expansion.Comment: 27 page
Suppression of Bremsstrahlung at Non-Zero Temperature
The first-order bremsstrahlung emission spectrum is
at zero temperature. If the radiation is emitted into a region that contains a
thermal distribution of photons, then the rate is increased by a factor
where is the Bose-Einstein function. The stimulated
emission changes the spectrum to for . If this were correct, an infinite amount of energy would be radiated in the
low frequency modes. This unphysical result indicates a breakdown of
perturbation theory. The paper computes the bremsstrahlung rate to all orders
of perturbation theory, neglecting the recoil of the charged particle. When the
perturbation series is summed, it has a different low-energy behavior. For
, the spectrum is independent of and has a value
proportional to .Comment: 16 pages (plain TeX), figures available on reques
Generalised chiral QED2 : Anomaly and Exotic Statistics
We study the influence of the anomaly on the physical quantum picture of the
generalized chiral Schwinger model defined on the circle. We show that the
anomaly i) results in the background linearly rising electric field and ii)
makes the spectrum of the physical Hamiltonian nonrelativistic without a
massive boson. The physical matter fields acquire exotic statistics . We
construct explicitly the algebra of the Poincare generators and show that it
differs from the Poincare one. We exhibit the role of the vacuum Berry phase in
the failure of the Poincare algebra to close. We prove that, in spite of the
background electric field, such phenomenon as the total screening of external
charges characteristic for the standard Schwinger model takes place in the
generalized chiral Schwinger model, too.Comment: LATEX file, 36 pp., to appear in Phys.Rev.
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