Meson Correlators in QCD Vacuum - is Saturation the Right Approach ?
  Equal time, point to point correlation functions for spatially separated meson currents are calculated with respect to a variational construct for the ground state of QCD. With exact calculations, vector, axial vector and scalar channels show qualitative agreement with the phenomenological predictions, where as pseudoscalar channel does not. However, the pseudoscalar correlator, when approximated by saturating with intermediate one pion states agrees with results obtained from spectral density functions parametrised by pion decay constant and $<\bar \psi \psi>$ value obtained from chiral perturbation theory. 
Varun Sheel, Hiranmaya Mishra and Jitendra C. Parikh