2,574 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
Twisted N=8, D=2 super Yang-Mills theory as example of a Hodge-type cohomological theory
It is shown that the dimensional reduction of the N_T=2, D=3 Blau-Thompson
model to D=2, i.e., the novel topological twist of N=8, D=2 super Yang-Mills
theory, provides an example of a Hodge-type cohomological theory. In that
theory the generators of the topological shift, co-shift and gauge symmetry,
together with a discrete duality operation, are completely analogous to the de
Rham cohomology operators and the Hodge *-operation.Comment: 8 pages, Late
A new look at the problem of gauge invariance in quantum field theory
Quantum field theory is assumed to be gauge invariant. However it is well
known that when certain quantities are calculated using perturbation theory the
results are not gauge invariant. The non-gauge invariant terms have to be
removed in order to obtain a physically correct result. In this paper we will
examine this problem and determine why a theory that is supposed to be gauge
invariant produces non-gauge invariant results.Comment: Accepted by Physica Scripta. 27 page
Duality and Superconvergence Relation in Supersymmetric Gauge Theories
We investigate the phase structures of various N=1 supersymmetric gauge
theories including even the exceptional gauge group from the viewpoint of
superconvergence of the gauge field propagator. Especially we analyze in detail
whether a new type of duality recently discovered by Oehme in gauge
theory coupled to fundamental matter fields can be found in more general gauge
theories with more general matter representations or not. The result is that in
the cases of theories including matter fields in only the fundamental
representation, Oehme's duality holds but otherwise it does not. In the former
case, superconvergence relation might give good criterion to describe the
interacting non-Abelian Coulomb phase without using some information from dual
magnetic theory.Comment: 20 pages, LaTe
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
The basic cohomology of the twisted N=16, D=2 super Maxwell theory
We consider a recently proposed two-dimensional Abelian model for a Hodge
theory, which is neither a Witten type nor a Schwarz type topological theory.
It is argued that this model is not a good candidate for a Hodge theory since,
on-shell, the BRST Laplacian vanishes. We show, that this model allows for a
natural extension such that the resulting topological theory is of Witten type
and can be identified with the twisted N=16, D=2 super Maxwell theory.
Furthermore, the underlying basic cohomology preserves the Hodge-type structure
and, on-shell, the BRST Laplacian does not vanish.Comment: 9 pages, Latex; new Section 4 showing the invariants added; 2
references and relating remarks adde
Pt-incorporated anatase TiO2(001) surface for solar cell applications : First-principles density functional theory calculations
First-principles density functional theory calculations were carried out to
determine the low energy geometries of anatase TiO(001) with Pt implants in
the sublayers as substitutional and interstitial impurities as well as on the
surface in the form of adsorbates. We investigated the effect of such a
systematic Pt incorporation in the electronic structure of this surface for
isolated and interacting impurities with an emphasis on the reduction in the
band gap to visible region. Comprehensive calculations, for 1x1 surface, showed
that Pt ions at interstitial cavities result in local segregation, forming
metallic wires inside, while substitution for bulk Ti and adsorption drives
four strongly dispersed impurity states from valence-bands up in the gap with a
narrowing of ~1.5 eV. Hence, such a contiguous Pt incorporation drives anatase
into infrared regime. Pt substitution for the surface Ti, on the other hand,
metallizes the surface. Systematic trends for 2x2 surface revealed that Pt can
be encapsulated inside to form stable structures as a result of strong Pt-O
interactions as well as the adsorptional and substitutional cases. Dilute
impurities considered for 2x2 surface models exhibit flat-like defect states
driven from the valence bands narrowing the energy gap suitable to obtain
visible light responsive titania.Comment: 15 pages, 8 figures, 4 tables. to appear on Phys. Rev
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