arXiv subjects

C. A. S. Almeida

Publications and source records attributed to C. A. S. Almeida.

151 records · Page 9Linked to original sources

arXiv2000

Nonabelian topological mass mechanism for a three-dimensional 2-form field

Starting from a recently proposed abelian topological model in (2+1) dimensions, we use the method of the consistent deformations to prove that a topologically massive model involving the Kalb-Ramond two form field does not admit a nonabelian generalization. The introduction of a connection-type one form field keeps the previous result. However we show that the goal is achieved if we introduce a vectorial auxiliary field, exhibiting a nonabelian topological mass generation mechanism in D=3, that provides mass for the Kalb-Ramond field. Further, we find the complete set of BRST and anti-BRST equations using the horizontality condition, suggesting a connection between this formalism and the method of the consistent deformations.

hep-th↗

arXiv2000

A superspace gauge-invariant formulation of a massive tridimensional 2-form field

By dimensional reduction of a massive supersymmetric B$\wedge $F theory, a manifestly N=1 supersymmetric completion of a massive antisymmetric tensor gauge theory is constructed in (2+1) dimensions. In the N=1-D=3 superspace, a new topological term is used to give mass for the Kalb-Ramond field. We have introduced a massive gauge invariant model using the Stuckelberg formalism and an abelian topologically massive theory for the Kalb-Ramond superfield. An equivalence of both massive models is suggested. Further, a component field analysis is performed, showing a second supersymmetry in the model.

hep-th↗

arXiv2000

Vortices in a nonminimal Maxwell-Chern-Simons O(3) Sigma Model

In this work we consider an Abelian O(3) sigma model coupled nonminimally with a gauge field governed by a Maxwell and Chern-Simons terms. Bogomol'nyi equations are constructed for a specific form of the potential and generic nonminimal coupling constant. Furthermore, topological and nontopological self-dual soliton solutions are obtained for a critical value of the nonminimal coupling constant. Some particular static vortex solutions (topological and nontopological) satisfying the Bogomol'nyi bound are numerically solved and presented.

hep-th↗

arXiv1999

Treating some solid state problems with the Dirac equation

The ambiguity involved in the definition of effective-mass Hamiltonians for nonrelativistic models is resolved using the Dirac equation. The multistep approximation is extended for relativistic cases allowing the treatment of arbitrary potential and effective-mass profiles without ordering problems. On the other hand, if the Schrodinger equation is supposed to be used, our relativistic approach demonstrate that both results are coincidents if the BenDaniel and Duke prescription for the kinetic-energy operator is implemented. Applications for semiconductor heterostructures are discussed.

cond-mat↗

arXiv1999

Non-Chern-Simons Topological Mass Generation in (2+1) Dimensions

By dimensional reduction of a massive BF theory, a new topological field theory is constructed in (2+1) dimensions. Two different topological terms, one involving a scalar and a Kalb-Ramond fields and another one equivalent to the four-dimensional BF term, are present. We constructed two actions with these topological terms and show that a topological mass generation mechanism can be implemented. Using the non-Chern-Simons topological term, an action is proposed leading to a classical duality relation between Klein-Gordon and Maxwell actions. We also have shown that an action in (2+1) dimensions with the Kalb-Ramond field is related by Buscher's duality transformation to a massive gauge-invariant Stuckelberg-type theory.

hep-th↗

arXiv1999

Pauli's Term and Fractional Spin

In this work we consider an Abelian Chern-Simons-Higgs model coupled non-minimally to matter fields. This coupling is implemented by means of a Pauli-type coupling. We show that the Pauli term is sufficient to gives rise to fractional spin.

hep-th↗

arXiv1997

Bogomol'nyi equations in gauge theories

By imposing self-duality conditions, we obtain the explicit form in which gauge theories spontaneously breakdown in the Bogomol'nyi limit. In this context, we reconsider the Abelian Higgs, Chern-Simons Higgs and Maxwell-Chern-Simons Higgs models. On the same footing, we find a topological Higgs potential for a Maxwell-Chern-Simons extended theory presenting both minimal and nonminimal coupling. Finally, we perform a numerical calculation in the asymmetric phase and show the solutions to the self-dual equations of motion of the topological theory. We argue about certain relations among the parameters of the model in order to obtain such vortex configurations.

hep-th↗