Regularization of two-dimensional quantum gravity

The gauge sector of two-dimensional quantum gravity, which plays a centralrole in string theory, cannot be regularized consistently by means of the usualdimensional-regularization method. As alternatives, dimensional reduction, avariant of dimensional regularization introduced in the context ofsupersymmetry, and /zeta/-function regularization are considered. Apart fromthe appearance of the conformal anomaly, dimensional reduction is found toviolate also two-dimensional general covariance, whereas /zeta/-functionregularization turns out to be symmetry preserving.