Non-critical holography and four-dimensional CFT's with fundamentals

We find non-critical string backgrounds in five and eight dimensions, holographically related to four-dimensional conformal field theories with = 0 and = 1 supersymmetries. In the five-dimensional case we find an AdS5 background metric for a string model related to non-supersymmetric, conformal QCD with large number of colors and flavors and discuss the conjectured existence of a conformal window from the point of view of our solution. In the eight-dimensional string theory, we build a family of solutions of the form AdS5 ? 3 with 3 a squashed three-sphere. For a special value of the ratio Nf/Nc, the background can be interpreted as the supersymmetric near-horizon limit of a system of color and flavor branes on 1,3 times a known four-dimensional generalization of the cigar. The = 1 dual theory with fundamental matter should have an IR fixed point only for a fixed ratio Nf/Nc. General features of the string/gauge theory correspondence for theories with fundamental flavors are also addressed.