Superpropagators for explicitly broken 3D-supersymmetric theories

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.

Remarks on the Causality, Unitarity and Supersymmetric Extension of the Lorentz and CPT-Violating Maxwell-Chern-Simons Model

The gauge-invariant Chern-Simons-type Lorentz- and CPT-breaking term is here re-assessed and issues like causality, unitarity, spontaneous gauge-symmetry breaking are investigated. Moreover, we obtain a minimal extension of such a system to a supersymmetric environment. We comment on resulting peculiar self-couplings for the gauge sector, as well as on background contribution for gaugino masses.Comment: 5 pages, NPB style, talk presented at "Renormalization Group and Anomalies in Gravity and Cosmology", Ouro Preto, Brazil, March 200

Graviton Excitations and Lorentz-Violating Gravity with Cosmological Constant

Motivated by the interest raised by the problem of Lorenz-symmetry violating gauge theories in connetion with gravity models, this contribution sets out to provide a general method to systematically study the excitation spectrum of gravity actions which include a Lorentz-symmetry breaking Chern-Simons-type action term for the spin connection. A complete set of spin-type operators is found which accounts for the (Lorentz) violation parameter to all orders and graviton propagators are worked out in a number of different situations

Discussing Quantum Aspects of Higher-Derivative 3D-Gravity in the First-Order Formalism

In this paper, we reassess the issue of deriving the propagators and identifying the spectrum of excitations associated to the vielbein and spin connection of (1+2)-D gravity in the presence of dynamical torsion, while working in the first-order formulation. A number of peculiarities is pointed out whenever the Chern-Simons term is taken into account along with a combination of bilinear terms in the torsion tensor. We present a procedure to derive the full set of propagators, based on an algebra of enlarged spin-type operators, and we discuss under which conditions the poles of the tree-level 2-point functions correspond to physical excitations that do not conflict with causality and unitarity

Remarks on Dirac-like Monopole, Maxwell and Maxwell-Chern-Simons Electrodynamics in D=(2+1)

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.

Topological Yang-Mills theories and their observables: a superspace approach

Théori