957 research outputs found
Structure of Multi-Meron Knot Action
We consider the structure of multi-meron knot action in the Yang-Mills theory
and in the CP^1 Ginzburg-Landau model. Self-dual equations have been obtained
without identifying orientations in the space-time and in the color space. The
dependence of the energy bounds on topological parameters of coherent states in
planar systems is also discussed. In particular, it is shown that a
characteristic size of a knot in the Faddeev-Niemi model is determined by the
Hopf invariant.Comment: 7 pages, Latex2
Kondo effect in the presence of spin-orbit coupling
We study the T=0 Kondo physics of a spin-1/2 impurity in a
non-centrosymmetric metal with spin-orbit interaction. Within a simple
variational approach we compute ground state properties of the system for an
{\it arbitrary} form of spin-orbit coupling consistent with the crystal
symmetry. This coupling produces an unscreened impurity magnetic moment and can
lead to a significant change of the Kondo energy. We discuss implications of
this finding both for dilute impurities and for heavy-fermion materials without
inversion symmetry.Comment: TeXLive (Unix), revtex4-1, 5 page
Yang-Mills and Born-Infeld actions on finite group spaces
Discretized nonabelian gauge theories living on finite group spaces G are
defined by means of a geometric action \int Tr F\wedge *F . This technique is
extended to obtain a discrete version of the Born-Infeld action.Comment: Talk presented at GROUP24, Paris, July 2002. LaTeX, 4 pages, IOP
style
Local physics of magnetization plateaux in the Shastry-Sutherland model
We address the physical mechanism responsible for the emergence of
magnetization plateaux in the Shastry-Sutherland model. By using a hierarchical
mean-field approach we demonstrate that a plateau is stabilized in a certain
{\it spin pattern}, satisfying {\it local} commensurability conditions derived
from our formalism. Our results provide evidence in favor of a robust local
physics nature of the plateaux states, and are in agreement with recent NMR
experiments on \scbo.Comment: 4 pages, LaTeX 2
Quantum group covariant noncommutative geometry
The algebraic formulation of the quantum group covariant noncommutative
geometry in the framework of the -matrix approach to the theory of quantum
groups is given. We consider structure groups taking values in the quantum
groups and introduce the notion of the noncommutative connections and
curvatures transformed as comodules under the "local" coaction of the structure
group which is exterior extension of . These noncommutative
connections and curvatures generate -covariant quantum algebras.
For such algebras we find combinations of the generators which are invariants
under the coaction of the "local" quantum group and one can formally consider
these invariants as the noncommutative images of the Lagrangians for the
topological Chern-Simons models, non-abelian gauge theories and the Einstein
gravity. We present also an explicit realization of such covariant quantum
algebras via the investigation of the coset construction
.Comment: 21 pages, improved versio
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