  We have examined effective theory induced by gauged WZW models, in which the
tachyon field is added as a marginal operator. Due to this operator added, we
must further add the higher order corrections, which modifies the original
configuration, to make the theory full-conformally invariant. It has been found
that 2d is a critical dimension in the sense that the metric obtained from
gauged WZW is modified by the tachyon condensation for $d>2$, but not for $d\le
2$.

High Energy Physics - Theory