Gauge/Gravity Duality, Green Functions of N=2 SYM and   Radial/Energy-Scale Relation
  We consider supergravity configuration of D5 branes wrapped on supersymmetric 2-cycles and use it to calculate one-point and two-point Green functions of some special operators in N=2 super Yang-Mills theory. We show that Green functions obtained from supergravity include two very different parts. One of them corresponds to perturbative results of quantum field theory, and another is a non-perturbative effect which corresponds to contribution from instantons with fractional charge. Comparing Green functions obtained from supergravity and gauge theory, we obtain radial/energy-scale relation for this gauge/gravity correspondence with N=2 supersymmetry. This relation leads right beta-function of N=2 SYM from supergravity configuration. 
Xiao-Jun Wang and Seng Hu