1,163 research outputs found
Parity violating cylindrical shell in the framework of QED
We present calculations of Casimir energy (CE) in a system of quantized
electromagnetic (EM) field interacting with an infinite circular cylindrical
shell (which we call `the defect'). Interaction is described in the only
QFT-consistent way by Chern-Simon action concentrated on the defect, with a
single coupling constant .
For regularization of UV divergencies of the theory we use % physically
motivated Pauli-Villars regularization of the free EM action. The divergencies
are extracted as a polynomial in regularization mass , and they renormalize
classical part of the surface action.
We reveal the dependence of CE on the coupling constant . Corresponding
Casimir force is attractive for all values of . For we
reproduce the known results for CE for perfectly conducting cylindrical shell
first obtained by DeRaad and Milton.Comment: Typos corrected. Some references adde
3D-4D Interlinkage Of qqq Wave Functions Under 3D Support For Pairwise Bethe-Salpeter Kernels
Using the method of Green's functions within a Bethe-Salpeter framework
characterized by a pairwise qq interaction with a Lorentz-covariant 3D support
to its kernel, the 4D BS wave function for a system of 3 identical relativistic
spinless quarks is reconstructed from the corresponding 3D form which satisfies
a fully connected 3D BSE. This result is a 3-body generalization of a similar
2-body result found earlier under identical conditions of a 3D support to the
corresponding qq-bar BS kernel under Covariant Instaneity (CIA for short). (The
generalization from spinless to fermion quarks is straightforward).
To set the CIA with 3D BS kernel support ansatz in the context of
contemporary approaches to the qqq baryon problem, a model scalar 4D qqq BSE
with pairwise contact interactions to simulate the NJL-Faddeev equations is
worked out fully, and a comparison of both vertex functions shows that the CIA
vertex reduces exactly to the NJL form in the limit of zero spatial range. This
consistency check on the CIA vertex function is part of a fuller accounting for
its mathematical structure whose physical motivation is traceable to the role
of `spectroscopy' as an integral part of the dynamics.Comment: 20 pages, Latex, submitted via the account of K.-C. Yan
The Boltzmann equation for colourless plasmons in hot QCD plasma. Semiclassical approximation
Within the framework of the semiclassical approximation, we derive the
Boltzmann equation describing the dynamics of colorless plasmons in a hot QCD
plasma. The probability of the plasmon-plasmon scattering at the leading order
in the coupling constant is obtained. This probability is gauge-independent at
least in the class of the covariant and temporal gauges. It is noted that the
structure of the scattering kernel possesses important qualitative difference
from the corresponding one in the Abelian plasma, in spite of the fact that we
focused our study on the colorless soft excitations. It is shown that
four-plasmon decay is suppressed by the power of relative to the process of
nonlinear scattering of plasmons by thermal particles at the soft momentum
scale. It is stated that the former process becomes important in going to the
ultrasoft region of the momentum scale.Comment: 41, LaTeX, minor changes, identical to published versio
Measurements of light background at large depth in the ocean
The mean intensity of Cerenkov emission from the products of K(40) decay and bioluminescence was measured at depths to 5 km. The intensity of ocean light background is found to depend upon depth and at the 5 km level is equal on averaged to 300 + or - 60 quanta/sq cms into spatial angle of 2 pi sterradian in transparency window. The amplitudes, duration and number of BL flashes were measured at various depths. The intensive flashes due to BL are shown to be observed rather seldom at depths over 4 km
A Cosmological Theory without Singularities
A theory of gravitation is constructed in which all homogeneous and isotropic
solutions are nonsingular, and in which all curvature invariants are bounded.
All solutions for which curvature invariants approach their limiting values
approach de Sitter space. The action for this theory is obtained by a higher
derivative modification of Einstein's theory. We expect that our model can
easily be generalized to solve the singularity problem also for anisotropic
cosmologies.Comment: 25 pages, 11 figures (available as hard copies from the authors),
uses phyzzx, BROWN-HET-89
Radiation of Charged Particles by Charged Black Hole
The probability of a charged particle production by the electric field of a
charged black hole depends essentially on the particle energy. This probability
is found in the nonrelativistic and ultrarelativistic limits. The range of
values for the mass and charge of a black hole is indicated where the discussed
mechanism of radiation is dominating over the Hawking one.Comment: 10 pages, latex, 4 ps-figure
Curing singularities: From the big bang to black holes
Singular spacetimes are a natural prediction of Einstein's theory. Most
memorable are the singular centers of black holes and the big bang. However,
dilatonic extensions of Einstein's theory can support nonsingular spacetimes.
The cosmological singularities can be avoided by dilaton driven inflation.
Furthermore, a nonsingular black hole can be constructed in two dimensions.Comment: To appear as a brief report in Phys. Rev.
Optical monitoring of the z=4.40 quasar Q 2203+292
We report Cousins R-band monitoring of the high-redshift (z=4.40) radio quiet
quasar Q 2203+292 from May 1999 to October 2007. The quasar shows maximum
peak-to-peak light curve amplitude of ~0.3 mag during the time of our
monitoring, and ~0.9 mag when combined with older literature data. The rms of a
fit to the light curve with a constant is 0.08 mag and 0.2 mag, respectively.
The detected changes are at ~3-sigma level. The quasar was in a stable state
during the recent years and it might have undergone a brightening event in the
past. The structure function analysis concluded that the object shows
variability properties similar to those of the lower redshift quasars. We set a
lower limit to the Q 2203+292 broad line region mass of 0.3-0.4 M_odot.
Narrow-band imaging search for redshifted Ly_alpha from other emission line
objects at the same redshift shows no emission line objects in the quasar
vicinity.Comment: 9 pages, 8 figures, accepted for publication in MNRA
Shock-wave and spalling phenomena in ultrafine-grained and coarse-grained (α + β) alloy Ti-Al-V treated by a nanosecond relativistic high-current electron beam
The results of experimental and theoretical research of shock-wave and spalling phenomena in ultrafine-grained and coarse-grained (α + β) alloy Ti–6.2% Al–4.0% V (wt %) treated by a nanosecond relativistic high-current electron beam are presented. Data on the dynamics of mass velocity, temperature and shock waves as well as on the interaction of the unloading wave with the rarefaction wave reflected from the back surface have been obtained for an axisymmetric position of the target. It is shown that the strain rate increase from 10−3 to 105 s−1 in the both grain structures does not change the fracture mechanism and the phase composition in the zone of spalling. The obtained theoretical dependence of the spalling layer thickness to the target thickness corresponds to experimental data
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