35,988 research outputs found
Monopoles and Knots in Skyrme Theory
We show that the Skyrme theory actually is a theory of monopoles which allows
a new type of solitons, the topological knots made of monopole-anti-monopole
pair,which is different from the well-known skyrmions. Furthermore, we derive a
generalized Skyrme action from the Yang-Mills action of QCD, which we propose
to be an effective action of QCD in the infra-red limit. We discuss the
physical implications of our results.Comment: 4 pages. Phys. Rev. Lett. in pres
Abelian Dominance in Wilson Loops
It has been conjectured that the Abelian projection of QCD is responsible for
the confinement of color. Using a gauge independent definition of the Abelian
projection which does {\it not} employ any gauge fixing, we provide a strong
evidence for the Abelian dominance in Wilson loop integral. In specific we
prove that the gauge potential which contributes to the Wilson loop integral is
precisely the one restricted by the Abelian projection.Comment: 4 pages, no figure, revtex. Phys. Rev. D in pres
Color Reflection Invariance and Monopole Condensation in QCD
We review the quantum instability of the Savvidy-Nielsen-Olesen (SNO) vacuum
of the one-loop effective action of SU(2) QCD, and point out a critical defect
in the calculation of the functional determinant of the gluon loop in the SNO
effective action. We prove that the gauge invariance, in particular the color
reflection invariance, exclude the unstable tachyonic modes from the gluon loop
integral. This guarantees the stability of the magnetic condensation in QCD.Comment: 28 pages, 3 figures, JHEP styl
QCD effective action with a most general homogeneous field background
We consider one-loop effective action of SU(3) QCD with a most general
constant chromomagnetic (chromoelectric) background which has two independent
Abelian field components. The effective potential with a pure magnetic
background has a local minimum only when two Abelian components H_{\mu\nu}^3
and H_{\mu\nu}^8 of color magnetic field are orthogonal to each other. The
non-trivial structure of the effective action has important implication in
estimating quark-gluon production rate and p_T-distribution in quark-gluon
plasma. In general the production rate depends on three independent Casimir
invariants, in particular, it depends on the relative orientation between
chromoelectric fields.Comment: 6 pages, 3 figures (9 pages in published version
Radiating sources in higher-dimensional gravity
We study a time-dependent 5D metric which contains a static 4D sub-metric
whose 3D part is spherically symmetric. An expansion in the metric coefficient
allow us to obtain close-to Schwarzschild approximation to a class of
spherically-symmetric solutions. Using Campbell's embedding theorem and the
induced-matter formalism we obtain two 4D solutions. One describes a source
with the stiff equation of state believed to be applicable to dense
astrophysical objects, and the other describes a spherical source with a radial
heat flow.Comment: Latex, 20 pages, no figures. to appear in J. Math. Phy
Fundamental study of flow field generated by rotorcraft blades using wide-field shadowgraph
The vortex trajectory and vortex wake generated by helicopter rotors are visualized using a wide-field shadowgraph technique. Use of a retro-reflective Scotchlite screen makes it possible to investigate the flow field generated by full-scale rotors. Tip vortex trajectories are visible in shadowgraphs for a range of tip Mach number of 0.38 to 0.60. The effect of the angle of attack is substantial. At an angle of attack greater than 8 degrees, the visibility of the vortex core is significant even at relatively low tip Mach numbers. The theoretical analysis of the sensitivity is carried out for a rotating blade. This analysis demonstrates that the sensitivity decreases with increasing dimensionless core radius and increases with increasing tip Mach number. The threshold value of the sensitivity is found to be 0.0015, below which the vortex core is not visible and above which it is visible. The effect of the optical path length is also discussed. Based on this investigation, it is concluded that the application of this wide-field shadowgraph technique to a large wind tunnel test should be feasible. In addition, two simultaneous shadowgraph views would allow three-dimensional reconstruction of vortex trajectories
On Signatures of Atmospheric Features in Thermal Phase Curves of Hot Jupiters
Turbulence is ubiquitous in Solar System planetary atmospheres. In hot
Jupiter atmospheres, the combination of moderately slow rotation and thick
pressure scale height may result in dynamical weather structures with unusually
large, planetary-size scales. Using equivalent-barotropic, turbulent
circulation models, we illustrate how such structures can generate a variety of
features in the thermal phase curves of hot Jupiters, including phase shifts
and deviations from periodicity. Such features may have been spotted in the
recent infrared phase curve of HD 189733b. Despite inherent difficulties with
the interpretation of disk-integrated quantities, phase curves promise to offer
unique constraints on the nature of the circulation regime present on hot
Jupiters.Comment: 22 pages, 6 figures, 1 table, accepted for publication in Ap
Strong and Electromagnetic Decays of Two New Baryons
Two recently discovered excited charm baryons are studied within the
framework of Heavy Hadron Chiral Perturbation Theory. We interpret these new
baryons which lie 308 \MeV and 340 \MeV above the as
members of a P-wave spin doublet. Differential and total decay rates for their
double pion transitions down to the ground state are calculated.
Estimates for their radiative decay rates are also discussed. We find that the
experimentally determined characteristics of the baryons may be
simply understood in the effective theory.Comment: 16 pages with 4 figures not included but available upon request,
CALT-68-191
Partially Dual variables in SU(2) Yang-Mills Theory
We propose a reformulation of SU(2) Yang-Mills theory in terms of new
variables. These variables are appropriate for describing the theory in its
infrared limit, and indicate that it admits knotlike configurations as stable
solitons. As a consequence we arrive at a dual picture of the Yang-Mills theory
where the short distance limit describes asymptotically free, massless point
gluons and the large distance limit describes extended, massive knotlike
solitons.Comment: 4 pages, revtex twocolum
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