AXIAL-VECTOR DUALITY AS A GAUGE-SYMMETRY AND TOPOLOGY CHANGE IN STRING THEORY

Lines generated by marginal deformations of WZW models are considered. The Weyl symmetry at the WZW point implies the existence of a duality symmetry on such lines. The duality is interpreted as a broken gauge symmetry in string theory. It is shown that at the two end points the axial and vector cosets are obtained. This shows that the axial and ve ctor cosets are equivalent CFTs both in the compact and the non-compac t cases. Moreover, it is shown that there are sigma-model deformations that interpolate smoothly between manifolds with different topologies .