22,990 research outputs found
Plastic Deformation of 2D Crumpled Wires
When a single long piece of elastic wire is injected trough channels into a
confining two-dimensional cavity, a complex structure of hierarchical loops is
formed. In the limit of maximum packing density, these structures are described
by several scaling laws. In this paper it is investigated this packing process
but using plastic wires which give origin to completely irreversible structures
of different morphology. In particular, it is studied experimentally the
plastic deformation from circular to oblate configurations of crumpled wires,
obtained by the application of an axial strain. Among other things, it is shown
that in spite of plasticity, irreversibility, and very large deformations,
scaling is still observed.Comment: 5 pages, 6 figure
Axial Vector Duality in Affine NA Toda Models
A general and systematic construction of Non Abelian affine Toda models and
its symmetries is proposed in terms of its underlying Lie algebraic structure.
It is also shown that such class of two dimensional integrable models naturally
leads to the construction of a pair of actions related by T-duality
transformationsComment: 9 pages, to appear in JHEP Proc. of the Workshop on Integrable
Theories, Solitons and Duality, IFT-Unesp, Sao Paulo, Brasil, one reference
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Noncommutativity due to spin
Using the Berezin-Marinov pseudoclassical formulation of spin particle we
propose a classical model of spin noncommutativity. In the nonrelativistic
case, the Poisson brackets between the coordinates are proportional to the spin
angular momentum. The quantization of the model leads to the noncommutativity
with mixed spacial and spin degrees of freedom. A modified Pauli equation,
describing a spin half particle in an external e.m. field is obtained. We show
that nonlocality caused by the spin noncommutativity depends on the spin of the
particle; for spin zero, nonlocality does not appear, for spin half, , etc. In the relativistic case the noncommutative
Dirac equation was derived. For that we introduce a new star product. The
advantage of our model is that in spite of the presence of noncommutativity and
nonlocality, it is Lorentz invariant. Also, in the quasiclassical approximation
it gives noncommutativity with a nilpotent parameter.Comment: 11 pages, references adda
T-Duality in Affine NA Toda Models
The construction of Non Abelian affine Toda models is discussed in terms of
its underlying Lie algebraic structure. It is shown that a subclass of such non
conformal two dimensional integrable models naturally leads to the construction
of a pair of actions which share the same spectra and are related by canonical
transformations.Comment: 6 pages, Presented at the 13th International Colloquium on Integrable
Systems and Quantum Groups, Prague, June, 200
T-Duality in 2-D Integrable Models
The non-conformal analog of abelian T-duality transformations relating pairs
of axial and vector integrable models from the non abelian affine Toda family
is constructed and studied in detail.Comment: 14 pages, Latex, v.2 misprints corrected, reference added, to appear
in J. Phys.
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