Glueball correlators as holograms
  We investigate the dynamical content of both hard- and soft-wall approximations to holographic QCD by deriving the corresponding glueball correlation functions and by confronting them with a variety of QCD results. We further calculate the glueball decay constants in both holographic duals, discuss emerging limitations and improvement strategies, and comment on a recent attempt to generalize the glueball correlator in the soft-wall background. 
Hilmar Forkel