Perfecting the ultra-violet of holographic descriptions of QCD

We investigate imposing a UV cutoff into a simple AdS/QCD model of the rho mesons. The cutoff corresponds to the scale at which QCD moves from perturbative to non-perturbative behaviour, above which the gravity dual will itself become strongly coupled. Simply imposing a cutoff significantly improves the fit to the masses of the tower of excited rho mesons. Formally one should match the couplings of higher dimension operators and the anomalous dimensions of fields to the QCD values at the cutoff. We explore examples of these matchings including looking at the anomalous dimensions of the q (q) over bar gamma(mu)q operators and including a G Tr F-4 coupling. (c) 2006 Elsevier B.V. All rights reserved.