A class of non abelian affine Toda models arising from the axial gauged two-loop WZW model is presented. Their zero curvature representation is constructed in terms of a graded Kac-Moody algebra. It is shown that the discrete multivacua structure of the potential together with non abelian nature of the zero grade subalgebra allows soliton solutions with non trivial electric and topological charges. The dressing transformation is employed to explicitly construct one and two soliton solutions and their bound states in terms of the tau functions. A discussion of the classical spectra of such solutions and the time delays are given in detail.

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The soliton spectrum (massive and massless) of a family of integrable models with local U(1) and U(1) ⊗ U(1) symmetries is studied. These models represent relevant integrable deformations of SL(2, R) ⊗ U(1) n−1 -WZW and SL(2, R) ⊗ SL(2, R) ⊗ U(1) n−2 -WZW models. Their massless solitons appear as specific topological solutions of the U(1) (or U(1) ⊗ U(1)) -CFTs. The nonconformal analog of the GKO-coset formula is derived and used in the construction of the composite massive solitons of the ungauged integrable models.

A general construction of affine nonabelian (NA)-Toda models in terms of the axial and vector gauged two loop WZNW model is discussed. They represent integrable perturbations of the conformal σ -models (with tachyons included) describing (charged) black hole type string backgrounds. We study the off-critical T-duality between certain families of axial and vector type integrable models for the case of affine NA-Toda theories with one global U(1) symmetry. In particular we find the Lie algebraic condition defining a subclass of T-selfdual torsionless NA-Toda models and their zero curvature representation. C

A bicomplex structure is associated to the Leznov-Saveliev equation of integrable models. The linear problem associated to the zero curvature condition is derived in terms of the bicomplex linear equation. The explicit example of a Non-Abelian Conformal Affine Toda model is discussed in detail and its conservation laws are derived from the zero curvature representation of its equation of motion.

Neste trabalho, produtos inultiplainente torcidos são definidos. Em casos particulares, relevantes à teoria da relatividade geral, analisam-se sob quais condições as variedades correspondentes são variedades de Einstein ou possuem curvatura escalar constante.