679 research outputs found
First-order framework and generalized global defect solutions
This work deals with defect structures in models described by scalar fields.
The investigations focus on generalized models, with the kinetic term modified
to allow for a diversity of possibilities. We develop a new framework, in which
we search for first-order differential equations which solve the equations of
motion. The main issue concerns the introduction of a new function, which works
like the superpotential usually considered in the standard situation. We
investigate the problem in the general case, with an arbitrary number of
fields, and we present several explicit examples in the case of a single real
scalar field.Comment: 8 pages, 6 figures; version to appear in PL
Topological Twistons in Crystalline Polyethylene
We introduce an alternate model to describe twistons in crystalline
polyethylene. The model couples torsional and longitudinal degrees of freedom
and appears as an extension of a model that describes only the torsional
motion. We find exact solutions that describe stable topological twistons, in
good agreement with the torsional and longitudinal interactions in
polyethylene.Comment: Latex, 10 pages; some stylistic corrections, to appear in Chemical
Physics Letter
General solutions for some classes of interacting two field kinks
In this work we present some classes of models whose the corresponding two
coupled first-order nonlinear equations can be put into a linear form, and
consequently be solved completely. In these cases the so-called trial orbit
method is completely unnecessary. We recall that some physically important
models as, for instance, the problem of tiling a plane with a network of
defects and polymer properties are in this class of models.Comment: 14 pages, 3 figure
Alternate route to soliton solutions in hydrogen-bonded chains
In this paper we offer an alternate route for investigating soliton solutions
in hydrogen-bonded chains. This is done by examining a class of systems of two
coupled real scalar fields. We show that this route allows investigating
several models for hydrogen-bonded chains in a unified manner. We also show how
to investigate interesting issues, in particular the one concerning classical
or linear stability of solitonic solutions.Comment: 12 pages. Late
Defect structures in sine-Gordon-like models
We investigate several models described by real scalar fields, searching for
topological defects. Some models are described by a single field, and support
one or two topological sectors, and others are two-field models, which support
several topological sectors. Almost all the defect structures that we find are
stable and finite energy solutions of first-order differential equations that
solve the corresponding equations of motion. In particular, for the double
sine-Gordon model we show how to find small and large BPS solutions as
deformations of the BPS solution of the model. And also, for most of
the two field models we find the corresponding integrating factors, which lead
to the complete set of BPS solutions, nicely unveiling how they bifurcate among
the several topological sectors.Comment: RevTex, 18 pages, 17 figures; Version to appear in Physica
Bloch Brane
We investigate a system described by two real scalar fields coupled with
gravity in (4, 1) dimensions in warped spacetime involving one extra dimension.
The results show that the parameter which controls the way the two scalar
fields interact induces the appearence of thick brane which engenders internal
structure, driving the energy density to localize inside the brane in a very
specific way.Comment: 13 pages, 6 figures; some misprints corrected, to appear in JHE
Global Defects in Field Theory with Applications to Condensed Matter
We review investigations on defects in systems described by real scalar
fields in (D,1) space-time dimensions. We first work in one spatial dimension,
with models described by one and two real scalar fields, and in higher
dimensions. We show that when the potential assumes specific form, there are
models which support stable global defects for D arbitrary. We also show how to
find first-order differential equations that solve the equations of motion, and
how to solve models in D dimensions via soluble problems in D=1. We illustrate
the procedure examining specific models and showing how they may be used in
applications in different contexts in condensed matter physics, and in other
areas.Comment: 15 pages, 9 figure
Supersymmetric extensions of k-field models
We investigate the supersymmetric extension of k-field models, in which the
scalar field is described by generalized dynamics. We illustrate some results
with models that support static solutions with the standard kink or the compact
profile.Comment: 11 page
Complete factorization of equations of motion in supersymmetric field theories
We investigate bosonic sectors of supersymmetric field theories. We consider
superpotentials described by one and by two real scalar fields, and we show how
the equations of motion can be factorized into a family of first order
Bogomol'nyi equations, so that all the topological defects are of the
Bogomol'nyi-Prasad-Sommerfield type. We examine explicit models, that engender
the Z_N symmetry, and we identify all the topological sectors, illustrating
their integrability.Comment: Revtex, 6 pages; version to be published in Nucl. Phys.
Scalar fields: from domain walls to nanotubes and fulerenes
In this work we review some features of topological defects in field theory
models for real scalar fields. We investigate topological defects in models
involving one and two or more real scalar fields. In models involving a single
field we examine two different subclasses of models, which support one or more
topological defects. In models involving two or more real scalar fields, we
explore the presence of defects that live inside topological defects, and
junctions and networks of defects. In the case of junctions of defects we
investigte structures that simulate nanotubes and fulerenes. Our investigations
may also be used to describe nonlinear properties of polymers, Langmuir films
and optical solitons in fibers.Comment: Revtex, 10 pages, 5 figures. Talk presented at XXII Encontro Nacional
de Fisica de Particulas e Campos, Sao Lourenco, MG, Brazil, October 2001; v2,
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