Physical states and scaling properties of W gravities and W strings

Abstract

We discuss some physical aspects of W gravities and W strings. We identify global characteristics in W gravities (in addition to the usual Euler characteristic) and show how the dependence of the partition function on the various chemical potentials involves these quantities. We find the operators which create physical states in W₃ and W₄ gravities and discuss their relationship with screening operators. W strings are discussed in the framework of a natural way of coupling "matter" to W gravity, and the issues of extra dimensions and critical dimensions are clarified. We find a remarkable relationship between pure W gravities and ordinary gravity coupled to c<1 unitary minimal models.