1,801 research outputs found
No confinement without Coulomb confinement
We compare the physical potential of an external quark-antiquark
pair in the representation of SU(N), to the color-Coulomb potential which is the instantaneous part of the 44-component of the gluon
propagator in Coulomb gauge, D_{44}(\vx,t) = V_{\rm coul}(|\vx|) \delta(t) +
(non-instantaneous). We show that if is confining, , then the inequality holds asymptotically at large , where is the Casimir in
the representation . This implies that is also
confining.Comment: 9 page
Superstring-Inspired E_6 Unification, Shadow Theta-Particles and Cosmology
We construct a new cosmological model considering the superstring-inspired
E_6 unification in the 4-dimensional space at the early stage of the Universe.
We develop a concept of parallel existence in Nature of the ordinary and shadow
worlds with different cosmological evolutions.Comment: 7 page
Superfield Approach to (Non-)local Symmetries for One-Form Abelian Gauge Theory
We exploit the geometrical superfield formalism to derive the local,
covariant and continuous Becchi-Rouet-Stora-Tyutin (BRST) symmetry
transformations and the non-local, non-covariant and continuous dual-BRST
symmetry transformations for the free Abelian one-form gauge theory in four -dimensions (4D) of spacetime. Our discussion is carried out in the
framework of BRST invariant Lagrangian density for the above 4D theory in the
Feynman gauge. The geometrical origin and interpretation for the (dual-)BRST
charges (and the transformations they generate) are provided in the language of
translations of some superfields along the Grassmannian directions of the six
(-dimensional supermanifold parametrized by the four spacetime and two
Grassmannian variables.Comment: LaTeX file, 23 page
Linear Sigma model in the Gaussian wave functional approximation II: Analyticity of the S-matrix and the effective potential/action
We show an explicit connection between the solution to the equations of
motion in the Gaussian functional approximation and the minimum of the
(Gaussian) effective potential/action of the linear model, as well as
with the N/D method in dispersion theory. The resulting equations contain
analytic functions with branch cuts in the complex mass squared plane.
Therefore the minimum of the effective action may lie in the complex mass
squared plane. Many solutions to these equations can be found on the second,
third, etc. Riemann sheets of the equation, though their physical
interpretation is not clear. Our results and the established properties of the
S-matrix in general, and of the N/D solutions in particular, guide us to the
correct choice of the Riemann sheet. We count the number of states and find
only one in each spin-parity and isospin channel with quantum numbers
corresponding to the fields in the Lagrangian, i.e. to Castillejo-Dalitz-Dyson
(CDD) poles. We examine the numerical solutions in both the strong and weak
coupling regimes and calculate the Kallen-Lehmann spectral densities and then
use them for physical interpretation.Comment: 14 pages, 4 ps figures, to appear in Nucl. Phy
Cohomological Operators and Covariant Quantum Superalgebras
We obtain an interesting realization of the de Rham cohomological operators
of differential geometry in terms of the noncommutative q-superoscillators for
the supersymmetric quantum group GL_{qp} (1|1). In particular, we show that a
unique superalgebra, obeyed by the bilinears of fermionic and bosonic
noncommutative q-(super)oscillators of GL_{qp} (1|1), is exactly identical to
that obeyed by the de Rham cohomological operators. A set of discrete symmetry
transformation for a set of GL_{qp} (1|1) covariant superalgebras turns out to
be the analogue of the Hodge duality * operation of differential geometry. A
connection with an extended BRST algebra obeyed by the nilpotent (anti-)BRST
and (anti-)co-BRST charges, the ghost charge and a bosonic charge (which is
equal to the anticommutator of (anti-)BRST and (anti-)co-BRST charges) is also
established.Comment: LaTeX file, 21 page
Abelian 2-form gauge theory: special features
It is shown that the four -dimensional (4D) free Abelian 2-form
gauge theory provides an example of (i) a class of field theoretical models for
the Hodge theory, and (ii) a possible candidate for the quasi-topological field
theory (q-TFT). Despite many striking similarities with some of the key
topological features of the two -dimensional (2D) free Abelian (and
self-interacting non-Abelian) gauge theories, it turns out that the 4D free
Abelian 2-form gauge theory is {\it not} an exact TFT. To corroborate this
conclusion, some of the key issues are discussed. In particular, it is shown
that the (anti-)BRST and (anti-)co-BRST invariant quantities of the 4D 2-form
Abelian gauge theory obey the recursion relations that are reminiscent of the
exact TFTs but the Lagrangian density of this theory is not found to be able to
be expressed as the sum of (anti-)BRST and (anti-)co-BRST exact quantities as
is the case with the {\it topological} 2D free Abelian (and self-interacting
non-Abelian) gauge theories.Comment: LaTeX, 23 pages, journal ref. give
On ghost condensation, mass generation and Abelian dominance in the Maximal Abelian Gauge
Recent work claimed that the off-diagonal gluons (and ghosts) in pure
Yang-Mills theories, with Maximal Abelian gauge fixing (MAG), attain a
dynamical mass through an off-diagonal ghost condensate. This condensation
takes place due to a quartic ghost interaction, unavoidably present in MAG for
renormalizability purposes. The off-diagonal mass can be seen as evidence for
Abelian dominance. We discuss why ghost condensation of the type discussed in
those works cannot be the reason for the off-diagonal mass and Abelian
dominance, since it results in a tachyonic mass. We also point out what the
full mechanism behind the generation of a real mass might look like.Comment: 7 pages; uses revtex
Observation of Very High Energy Gamma Rays from HESS J1804-216 with CANGAROO-III Telescopes
We observed the unidentified TeV gamma-ray source HESS J1804-216 with the
CANGAROO-III atmospheric Cerenkov telescopes from May to July in 2006. We
detected very high energy gamma rays above 600 GeV at the 10 sigma level in an
effective exposure of 76 hr. We obtained a differential flux of
(5.0+/-1.5_{stat}+/-1.6_{sys})\times 10^{-12}(E/1 TeV)^{-\alpha}
cm^{-2}s^{-1}TeV^{-1} with a photon index \alpha of 2.69 +/- 0.30_{stat} +/-
0.34_{sys}, which is consistent with that of the H.E.S.S. observation in 2004.
We also confirm the extended morphology of the source. By combining our result
with multi-wavelength observations, we discuss the possible counterparts of
HESS J1804-216 and the radiation mechanism based on leptonic and hadronic
processes for a supernova remnant and a pulsar wind nebula.Comment: 11 pages, 12 figures, Accepted in Ap
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