Gravity-scalar fluctuations in holographic RG flow geometries

We study five-dimensional gravity models with non-vanishing background scal ar fields which are dual to non-conformal boundary field theories. We devel op a procedure to decouple the graviton fluctuations from the scalar ones a nd apply it to the simplest case of one scaler field, The quadratic action for the decoupled scaler fluctuations has a very simple form and can be use d to compute two-point functions. We perform this computation for the two e xamples of background RG now recently considered by DeWolfe and Freedman an d find physically reasonable results. (C) 2000 Elsevier Science B.V. All ri ghts reserved.