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We study vortex-like configuration in Maxwell-Chern-Simons Electrodynamics. Attention is paid to the similarity it shares with the Nielsen-Olesen solutions at large distances. A magnetic symmetry between a point-like and an azimuthal-like current in this framework is also pointed out. Furthermore, we address the issue of a neutral and spinless particle interacting with a charged vortex, and obtain that the Aharonov-Casher-type phase depends upon mass and distance parameters., Comment: New refs. added. Version accepted for publication in Phys. Lett. A

We start from a parity-breaking MCS QED$_{3}$ model with spontaneous breaking of the gauge symmetry as a framework for evaluation of the electron-electron interaction potential and for attainment of numerical values for the e-e bound state. Three expressions are obtained for the potential according to the polarization state of the scattered electrons. In an energy scale compatible with Condensed Matter electronic excitations, these three potentials become degenerated. The resulting potential is implemented in the Schrodinger equation and the variational method is applied to carry out the electronic binding energy. The resulting binding energies in the scale of 10-100 meV and a correlation length in the scale of 10-30 Angs. are possible indications that the MCS-QED$_{3}$ model adopted may be suitable to address an eventual case of e-e pairing in the presence of parity-symmetry breakdown. The data analyzed here suggest an energy scale of 10-100 meV to fix the breaking of the U(1)-symmetry. PACS numbers: 11.10.Kk 11.15.Ex 74.20.-z 74.72.-h ICEN-PS-01/17, Comment: 13 pages, style revtex, revised version

In this paper, following a stream of investigation on supersymmetric gauge theories with cosmic string solutions, we contemplate the possibility of building up a D-and-F term cosmic string by means of a gauge-field mixing in connection with a U(1) x U(1)'-symmetry. The spontaneous break of both gauge symmetry and supersymmetry are thoroughly analysed and the fermion zero-modes are worked out. The role of the gauge-field mixing parameter is elucidated in connection with the string configuration that comes out. As an application of the model presented here, we propose the possibility that the supersimetric cosmic string yield production of fermionic charge carriers that may eject, at their late stages, particles that subsequently decay to produce cosmic rays of ultra-high energy. In our work, it turns out that massive supersymmetric fermionic partners may be produced for a susy breaking scale in the range 10^{11} to 10^{13} GeV, which is compatible with the phenomenology of a gravitino mass at the TeV scale. We also determine the range of the gauge-field mixing parameter, \alpha, in connection with the mass scales of the present model., Comment: 7 pages, no figures, ReVTex format, to appear in New Journal of Physics

The gauge-invariant Chern-Simons-type Lorentz- and CPT-breaking term is here reassessed and a spin-projector method is adopted to account for the breaking (vector) parameter. Issues like causality, unitarity, spontaneous gauge-symmetry breaking and vortex formation are investigated, and consistency conditions on the external vector are identified., Comment: 12 pages, latex

One considers the quantum dynamics of a charged spin-1/2 particle in an extended external eletromagnetic field that arises from the reduction of a 5-dimensional Abelian gauge theory. The non-relativistic regime of the reduced 4D-dynamics is worked out and one identifies the system as a sector of an N=2-supersymmetric quantum-mechanical dynamics. The full supersymmetric model is studied and one checks the algebra of the fermionic charges; the conclusion is that no central charge drops out. The possible r\^ole of the extra external fields, a scalar and a magnetic-like field, is discussed., Comment: 19 pages. Latex format. No figures

A generic massive Thirring Model in three space-time dimensions exhibits a correspondence with a topologically massive bosonized gauge action associated to a self-duality constraint, and we write down a general expression for this relationship. We also generalize this structure to $d$ dimensions, by adopting the so-called doublet approach, recently introduced. In particular, a non- conventional formulation of the bosonization technique in higher dimensions (in the spirit of $d=3$), is proposed and, as an application, we show how fermionic (Thirring-like) representations for bosonic topologically massive models in four dimensions may be built up., Comment: Revised version, to appear in Phys. Rev. D

By considering the Higgs mechanism in the framework of a parity-preserving Planar Quantum Electrodynamics, one shows that an attractive electron-electron interaction may come out. The e-e interaction potential emerges as the non-relativistic limit of the Moller scattering amplitude and it may result attractive with a suitable choice of parameters. Numerical values of the e-e binding energy are obtained by solving the two-dimensional Schrodinger equation. The existence of bound states is to be viewed as an indicative that this model may be adopted to address the pairing mechanism in some systems endowed with parity-preservation., Comment: 6 pages, 1 table, style revtex

The mechanism of dynamical mass generation for the gauge field is studied through 1-loop. We find out that torsion is an obstruction to the appearance of a 1-loop mass correction. Contrary, if torsion is not present, a mass gap is generated for the 2-form field., Comment: 9 pages, 2 figures

Abelian Lagrangians containing $\lambda\phi^{4}$-type vertices are regularized by means of a suitable point-splitting scheme combined with generalized gauge transformations. The calculation is developped in details for a general Lagrangian whose fields (gauge and matter ones) satisfy usual conditions. We illustrate our results by considering some special cases, such as the $(\bar{\psi}\psi)^{2}$ and the Avdeev-Chizhov models. Possible application of our results to the Abelian Higgs model, whenever spontaneous symmetry breaking is considered, is also discussed. We also pay attention to a number of features of the point-split action such as the regularity and non-locality of its new ``interacting terms''., Comment: 11 pages, no figures. Latex format. Submitted to New Journal Physics

Dirac-like monopoles are studied in three-dimensional Abelian Maxwell and Maxwell-Chern-Simons models. Their scalar nature is highlighted and discussed through a dimensional reduction of four-dimensional electrodynamics with electric and magnetic sources. Some general properties and similarities of them when are considered in Minkowski or Euclidian space are mentioned. However, by virtue of the structure of the space-time in which they are considered a number of differences among them take place. Furthermore, we pay attention to some consequences of these objects when acting upon usual particles. Among other subjects, special attention is given to the study of a Lorentz-violating non-minimal coupling between neutral fermions and the field generated by a monopole alone. In addition, an analogue of the Aharonov-Casher effect is discussed in this framework., Comment: 20 pages. Latex format. No figures. Accepted for publication in Phys. Rev. D

Following a previous work on Abelian (2,0)-gauge theories, one reassesses here the task of coupling (2,0) relaxed Yang-Mills superpotentials to a (2,0)- nonlinear $\sigma$-model, by gauging the isotropy or the isometry group of the latter. One pays special attention to the extra ``chiral-like'' component-field gauge potential that comes out from the relaxation of superspace constraints., Comment: 11 pages, Latex

Huyghens principle and Planck law are studied in Maxwell and Maxwell-Chern-Simons frameworks in (2+1) dimensions. Contrary to (3+1) dimensions, massless photons are shown to violate Huyghens principle in planar world. In addition, we obtain that Planck law is no longer proportional to $\nu^3$, but to the squared frequency, $\nu^2$, of the planar photons. We also briefly discuss possible physical consequences of these results., Comment: 10 pages, no figures. Latex format

We consider a parity-preserving QED_3 model with spontaneous breaking of the gauge symmetry as a framework for the evaluation of the electron-electron interaction potential underlying high-T_c superconductivity. The fact that the resulting potential, -C_s K_{0}(Mr), is non-confining and ``weak'' (in the sense of Kato) strongly suggests the mechanism of pair-condensation. This potential, compatible with an s-wave order parameter, is then applied to the Schr\"odinger equation for the sake of numerical calculations, thereby enforcing the existence of bound states. The results worked out by means of our theoretical framework are checked by considering a number of phenomenological data extracted from different copper oxide superconductors. The agreement may motivate a deeper analysis of our model viewing an application to quasi-planar cuprate superconductors. The data analyzed here suggest an energy scale of 1-10 meV for the breaking of the U(1)-symmetry., Comment: 12 pages, Revtex (Tables included); corrected sign misprint; results improved

One discusses the issue of low-energy electron-electron bound states in the Maxwell-Chern-Simons model coupled to QED3 with spontaneous breaking of a local U(1)-symmetry. The scattering potential, in the non-relativistic limit, steaming from the electron-electron Moller scattering, mediated by the Maxwell-Chern-Simons-Proca gauge field and the Higgs scalar, might be attractive by fine-tuning properly the physical parameters of the model., Comment: 11 pages, 1 figure, RevTex. Dedicated to the memory of George Leibbrandt

We study a cosmic string solution of an N=1-supersymmetric version of the Cremmer-Scherk-Kalb-Ramond (CSKR) Lagrangian coupled to a vector superfield by means of a topological mass term. The 2-form gauge potential is proposed to couple non-minimally to matter, here described by a chiral scalar superfield. The important outcome is that supersymmetry is kept exact both in the core and in the exterior region of the string. We contemplate the bosonic configurations and it can be checked that the solutions saturate the Bogomolnyi bound. A glimpse on the fermionic zero modes is also given., Comment: 14 pages, LaTeX, presented at the XXI "Encontro Nacional de Fisica de Particulas e Campos", Sao Lourenco, MG, Brazil, with zero modes added

The low-energy electron-electron scattering potential is derived and discussed for the Maxwell-Chern-Simons model coupled to QED_3 with spontaneous symmetry breaking. One shows that the Higgs mechanism might favour electron-electron bound states., Comment: 5 pages, latex, contribution to the proceedings of the "XXI Encontro Nacional de Fisica de Particulas e Campos", October 2000, Sao Lourenco, Brazil

In this talk, we present a parity-preserving QED3 model with spontaneous breaking of a local U(1)-symmetry. The breaking is accomplished by a potential of the phi^6-type. It is shown that a net attractive interaction appears in the Moeller scattering (s- and p-wave scatterings between two electrons) as mediated by the gauge field and a Higgs scalar. We show, by solving numerically the Schroedinger equation for both the scattering potentials (s- and p-wave), that in the weak-coupling regime only s-wave bound states appear, whereas in the strong-coupling regime s- and p-wave bound states show up. Also, we discuss possible applications of the model to the phenomenology of high-Tc superconductors and to the re-entrant superconductivity effect., Comment: 5 pages, latex, contribution to the proceedings of the "XXI Encontro Nacional de Fisica de Particulas e Campos", October 2000, Sao Lourenco, Brazil

At first, we discuss parallels electric and magnetic fields solutions in a gravitational background. Then, considering eletromagnetic and gravitational waves symmetries we show a particular solution for stationary gravitational waves. Finally we consider gravitation as a gauge theory (effective gravitational theory), evaluate the propagators of the model, analyze the corresponding quantum excitations and verify (confirm) the tree-level unitarity at many places of the model., Comment: 13 pages, AMStex

The existence of an electromagnetic field with parallel electric and magnetic field components in the presence of a gravitational field is considered. A non-parallel solution is shown to exist. Next, we analyse the possibility of finding stationary gravitational waves in nature. Finally, we construct a D=4 effective quantum gravity model. Tree-level unitarity is verified., Comment: 6 pages, LaTex

Following a previous work on Abelian (2,0)-gauge theories, one reassesses here the task of coupling (2,0) relaxed Yang-Mills super-potentials to a (2,0)-nonlinear Sigma-model, by gauging the isotropy or the isometry group of the latter. One pays special attention to the extra "chiral-like" component-field gauge potential that comes out from the relaxation of constraints., Comment: 14 pages, revised version, Latex

Classical Maxwell and Maxwell-Chern-Simons (MCS) Electrodynamics in (2+1)D are studied in some details. General expressions for the potential and fields are obtained for both models, and some particular cases are explicitly solved. Conceptual and technical difficulties arise, however, for accelerated charges. The propagation of electromagnetic signals is also studied and their reverberation is worked out and discussed. Furthermore, we show that a Dirac-like monopole yields a (static) tangential electric field. We also discuss some classical and quantum consequences of the field created by such a monopole when acting upon an usual electric charge. In particular, we show that at large distances, the dynamics of one single charged particle under the action of such a potential and a constant (external) magnetic field as well, reduces to that of one central harmonic oscillator, presenting, however, an interesting angular sector which admits energy-eigenvalues. Among other peculiarities, both sectors, the radial and the angular one, present non-vanishing energy-eigenvalues for their lowest level. Moreover, those associated to the angle are shown to respond to discrete shifts of such a variable. We also raise the question whether the formation of bound states is possible in the system., Comment: 17 pages, 2 figures. To appear in Phys. Rev. D

We study the modifications on the metric of an isolated self-gravitating bosonic superconducting cosmic string in a scalar-tensor gravity in the weak-field approximation. These modifications are induced by an arbitrary coupling of a massless scalar field to the usual tensorial field in the gravitational Lagrangian. The metric is derived by means of a matching at the string radius with a most general static and cylindrically symmetric solution of the Einstein-Maxwell-scalar field equations. We show that this metric depends on five parameters which are related to the string's internal structure and to the solution of the scalar field. We compare our results with those obtained in the framework of General Relativity., Comment: 23 pages, no figures, LATEX file

In this comment we discuss some serious inconsistencies presented by Gomes, Malacarne and da Silva in their paper, Phys.Rev. D60 (1999) 125016 (hep-th/9908181)., Comment: 2 pages, RevTex, no figures

We discuss the possibility to construct an effective quantum field theory for an axial vector coupled to a Dirac spinor field. A massive axial vector describes antisymmetric torsion. The consistency conditions include unitarity and renormalizability in the low-energy region. The investigation of the Ward identities and the one- and two-loop divergences indicate serious problems arising in the theory. The final conclusion is that torsion may exist as a string excitation, but there are very severe restrictions for the existence of a propagating torsion field, subject to the quantization procedure, at low energies., Comment: LaTeX, 26 pages, 4 figures

The leading long-distance 1-loop quantum corrections to the Coulomb potential are derived for scalar QED and their gauge-independence is explicitly checked. The potential is obtained from the direct calculation of the 2-particle scattering amplitude, taking into account all relevant 1-loop diagrams. Our investigation should be regarded as a first step towards the same programme for effective Quantum Gravity. In particular, with our calculation in the framework of scalar QED, we are able to demonstrate the incompleteness of some previous studies concerning the Quantum Gravity counterpart., Comment: LaTeX, 16 pages, 4 figures as one ps-file

We study the implications of a scalar-tensorial gravity for the metric of an isolated self-gravitating superconducting cosmic string. These modifications are induced by an arbitrary coupling of a massless scalar field to the usual tensorial field in the gravitational Lagrangian. We derive the metric in the weak-field approximation and we analyse the behaviour of light in this spacetime. We end with some discussions., Comment: 12 pp, Latex, no figures, based on a talk given by M. E. X. Guimaraes at the COSMO 99, 27/9 to 02/10/99, ICTP, Trieste, It

A systematic algorithm to derive superpropagators in the case of either explicitly or spontaneously broken supersymmetric three-dimensional theories is presented. We discuss how the explicit breaking terms that are introduced at tree-level induce 1-loop radiative corrections to the effective action. We also point out that the renormalisation effects and the breaking-inducing-breaking mechanism become more immediate whenever we adopt the shifted superpropagators discussed in this letter., Comment: 6 pages, LaTex, references added. To appear in Phys.Lett.B

We consider some aspects of conformal symmetry in a metric-scalar-torsion system. It is shown that, for some special choice of the action, torsion acts as a compensating field and the full theory is conformally equivalent to General Relativity on classical level. Due to the introduction of torsion, this equivalence can be provided for the positively-defined gravitational and scalar actions. One-loop divergences arising from the scalar loop are calculated and both the consequent anomaly and the anomaly-induced effective action are derived., Comment: 15 pages, LaTeX. Essentially extended version, in particular the discussion of the stability of the conformal factor in gravity theory with torsion and scalar added. Title also modified. To be published in Physics Letters B

In this paper, fermions are minimally coupled to 3D-gravity where a dynamical torsion is introduced. A Kalb-Ramond field is non-minimally coupled to these fermions in a gauge-invariant way. We show that a 1-loop mass generation mechanism takes place for both the 2-form gauge field and the torsion. As for the fermions, no mass is dynamically generated: at 1-loop, there is only a mass shift proportional to the Yukawa coupling whenever the fermions have a non-vanishing tree-level mass., Comment: 13 pages, latex file, no figures, some corrections added

The paper was withdrawn by the authors., Comment: This paper has been withdrawn

A rigorous algebraic proof of the full finiteness in all orders of perturbation theory is given for the Yang-Mills-Chern-Simons theory in a general three-dimensional Riemannian manifold. We show the validity of a trace identity, playing the role of a local form of the Callan-Symanzik equation, in all loop orders, which yields the vanishing of the beta-functions associated to the topological mass and gauge coupling constant as well as the anomalous dimensions of the fields., Comment: 5 pages, revtex

We study and discuss some of the consequences of the inclusion of torsion in 3D Einstein-Chern-Simons gravity. Torsion may trigger the excitation of non-physical modes in the spectrum. Higher-derivative terms are then added up and tree-level unitarity is contemplated., Comment: 16 pages, Latex, new results added

An Abelian gauge model, with vector and 2-form potential fields linked by a topological mass term that mixes the two Abelian factors, is shown to exhibit Dirac-like magnetic monopoles in the presence of a matter background. In addition, considering a "non-minimal coupling" between the fermions and the tensor field, we obtain a generalised quantisation condition that involves, among others, the mass parameter. Also, it is explicitly shown that 1_loop (finite) corrections do not shift the value of such a mass parameter., Comment: 11 pages, 1 figure (Feynman graph)

Abelian Lagrangians containing Phi^4-type vertices are regularized by means of a suitable point-splitting scheme combined with generalized gauge transformations.. The calculation is developed in details for a general Lagrangean, whose fields (gauge and matter ones) satisfy usual conditions. We illustrate our results by considering some special cases, such as the ($\overline{\psi}\psi)^2 and a modified version of the Avddev-Chizhov models. Possible application of our results to the Abelian Higgs model, whenever spontaneous symmetry breaking is considered, is also discussed. We also pay attention to a number of features of the point-split action such as the regularity and non-locality of its new ``interacting terms''., Comment: 11 pages. New corrected version: some minors errors corrected, new references added

We analyse the structure of N=1 and N=2 supersymmetric non-linear sigma-models built up with a pair of real superfields defined in the superspace of Atiyah-Ward space-time. The geometry arising has new features such as the existence of a locally product structure (N=1 case) and a set of automorphisms of the tangent space that is isomorphic to the split-quaternionic algebra (N=2 case)., Comment: 12 pages, no figures

The equivalence between rank-2 anti-symmetric tensor fields, considered as gauge potentials, and torsionless non-linear $\sigma$-models suggests us to study the possibility of coupling tensorial matter with Yang-Mills fields, through the gauging of the isometries of the target space. We show that this coupling is actually possible; however, the matter appears no longer as an elementary field, but rather as a composite one, expressed in terms of the bosonic degrees of freedom of the $\sigma$-model. A possible phenomenological application is presented that describes the interactions among vector mesons in terms of the geometrical properties of the target manifold. Also, spin-2 meson resonances may naturally be accommodated whenever the $\sigma$-model's target manifold is non-symmetric., Comment: 9 pages, Latex

We find self-dual vortex solutions in a Maxwell-Chern-Simons model with anomalous magnetic moment. From a recently developed N=2-supersymmetric extension, we obtain the proper Bogomol'nyi equations together with a Higgs potential allowing both topological and non-topological phases in the theory., Comment: 12 pages, 9 figures, 2 tables; some typos corrected, one reference updated. To be published in the Int. J. Mod. Phys. A (1999)

One discusses here the connection between \sigma-model gauge anomalies and the existence of a connection with torsion that does not flatten the Ricci tensor of the target manifold, by considering a number of non-symmetric coset spaces. The influence of an eventual anisotropy on a certain direction of the target manifold is also contemplated., Comment: 11 pages, title changed, a new example of coset space was added that elucidates our claim

An N=1--supersymmetric version of the Cremmer-Scherk-Kalb-Ramond model with non-minimal coupling to matter is built up both in terms of superfields and in a component-field formalism. By adopting a dimensional reduction procedure, the N=2--D=3 counterpart of the model comes out, with two main features: a genuine (diagonal) Chern-Simons term and an anomalous magnetic moment coupling between matter and the gauge potential., Comment: 15 pages, Latex; one reference corrected; To be published in the Int. J. Mod. Phys. A

We analyse the renormalizability of an Abelian N=1 super-Chern-Simons model coupled to parity-preserving matter on the light of the regularization independent algebraic method. The model shows to be stable under radiative corrections and to be gauge anomaly free., Comment: Latex, 7 pages, no figures

In this letter the algebraic renormalization method, which is independent of any kind of regularization scheme, is presented for the parity-preserving QED_3 coupled to scalar matter in the broken regime, where the scalar assumes a finite vacuum expectation value, $<\vf> = v$. The model shows to be stable under radiative corrections and anomaly free., Comment: 9 pages, latex, no figures

In this letter the algebraic renormalization method, which is independent of any kind of regularization scheme, is presented for the parity-preserving QED_3 coupled to scalar matter in the symmetric regime, where the scalar assumes vanishing vacuum expectation value, $<\phi>=0$. The model shows to be stable under radiative corrections and anomaly free., Comment: 9 pages, latex, no figures

The existence of an electromagnectic field with parallel electric and magnetic components is readdressed in the presence of a gravitational field. A non-parallel solution is shown to exist. Next, we analyse the possibility of finding stationary gravitational waves in de nature. Finaly, We construct a D=4 effective quantum gravity model. Tree-level unitarity is verified., Comment: 6 pages, Latex

In this paper, we present a parity-preserving QED3 with spontaneous breaking of a local U(1)-symmetry. The breaking is accomplished by a potential of the \vf^6-type. It is shown that a net attractive interaction appears in the M{\o}ller scattering (s and p-wave scattering between two electrons) as mediated by the gauge field and a Higgs scalar. This might favour a pair-condensation mechanism., Comment: 16 pages, Latex, revised version, appendix and references added

The supersymmetric generalization of a recently proposed Abelian axial gauge model with antisymmetric tensor matter fields is presented., Comment: 12 pages, Latex, no figures. The section concerning symmetry breaking is revised, leading to new conclusions. A discussion on the spinorial degrees of freedom is included, and references are added

We present a supersymmetric non-linear $\s$-model built up in the $N=1$ superspace of Atiyah-Ward space-time. A manifold of the K\"ahler type comes out that is restricted by a particular decomposition of the K\"ahler potential. The gauging of the $\s$-model isometries is also accomplished in superspace., Comment: 15 pages, Latex, no figures