TENSOR AND NONLINEAR (4,4)SUPERMULTIPLETS IN SU(2)XSU(2) HARMONIC SUPERSPACE

We define the SU(2) x SU(2) harmonic superspace analogues of tensor an d nonlinear (4, 4), 2D supermultiplets. They are described by constrai ned analytic superfields and provide an off-shell formulation of a cla ss of torsionful (4, 4) supersymmetric sigma models with Abelian trans lational isometries on the bosonic target. We examine their relation t o (4, 4) twisted multiplets and discuss different types of (4, 4) dual ities associated with them. One of these dualities implies the standar d Abelian T-duality relations between the bosonic targets in the initi al and dual sigma model actions. We show that the N = 4, 2D superconfo rmal group admits a simple realization on the superfields introduced a nd presents a new superfield form of the (4, 4) SU(2) x U(1) WZNW acti on.