Affine Poisson and affine quasi-Poisson T-duality

We generalize the Poisson-Lie T-duality by making use of the structure of the affine Poisson group which is the concept introduced some time ago in Poisson geometry as a generalization of the Poisson-Lie group. We also introduce a new notion of an affine quasi-Poisson group and show that it gives rise to a still more general T-duality framework. We establish for a class of examples that this new T-duality is compatible with the renormalization group flow.Comment: 36 pages, Section 7 is added which explains the relations of the affine (quasi-)Poisson T-duality to the theory of dressing cosets, there are some stylistic improvements also in other section

Gauge theories on the noncommutative sphere

Gauge theories are formulated on the noncommutative two-sphere. These theories have only finite number of degrees of freedom, nevertheless they exhibit both the gauge symmetry and the SU(2) "Poincar\'e" symmetry of the sphere. In particular, the coupling of gauge fields to chiral fermions is naturally achieved.Comment: 33 pages, LaTe

A nonperturbative regularization of the supersymmetric Schwinger model

It is shown that noncommutative geometry is a nonperturbative regulator which can manifestly preserve a space supersymmetry and a supergauge symmetry while keeping only a finite number of degrees of freedom in a theory. The simplest N=1 case of an U(1) supergauge theory on the sphere is worked out in detail.Comment: 29 pages, LaTe

The formulae of Kontsevich and Verlinde from the perspective of the Drinfeld double

A two dimensional gauge theory is canonically associated to every Drinfeld double. For particular doubles, the theory turns out to be e.g. the ordinary Yang-Mills theory, the G/G gauged WZNW model or the Poisson $\sigma$-model that underlies the Kontsevich quantization formula. We calculate the arbitrary genus partition function of the latter. The result is the $q$-deformation of the ordinary Yang-Mills partition function in the sense that the series over the weights is replaced by the same series over the $q$-weights. For $q$ equal to a root of unity the series acquires the affine Weyl symmetry and its truncation to the alcove coincides with the Verlinde formula.Comment: 36 pages, LaTeX, references adde

An extended fuzzy supersphere and twisted chiral superfields

A noncommutative associative algebra of N=2 fuzzy supersphere is introduced. It turns out to possess a nontrivial automorphism which relates twisted chiral to twisted anti-chiral superfields and hence makes possible to construct noncommutative nonlinear \si-models with extended supersymmetry.Comment: 20 pages, LaTe

Poisson-Lie T-duals of the bi-Yang-Baxter models

We prove the conjecture of Sfetsos, Siampos and Thompson that suitable analytic continuations of the Poisson-Lie T-duals of the bi-Yang-Baxter sigma models coincide with the recently introduced generalized lambda models. We then generalize this result by showing that the analytic continuation of a generic sigma model of "universal WZW-type" introduced by Tseytlin in 1993 is nothing but the Poisson-Lie T-dual of a generic Poisson-Lie symmetric sigma model introduced by Klimcik and Severa in 1995.Comment: 15 pages, we present an additional result that the analytic continuation of a generic sigma model of "universal WZW-type" introduced by Tseytlin in 1993 is nothing but the Poisson-Lie T-dual of a generic Poisson-Lie symmetric sigma model introduced by Klimcik and Severa in 199