Modelling the Off-Shell Dependence of $\pi^{o}- \eta$ Mixing with Quark   Loops
  It is shown that including form factors for the quark-pseudoscalar meson couplings of the Georgi-Manohar chiral quark model allows one to obtain the leading off-shell dependence of $\pi^{o}- \eta$ mixing (as predicted by chiral perturbation theory) from the effect of quark loops on the meson propagators. Implications for $\rho^{o} - \omega$ mixing and for the effects on meson mixing contributions to few body charge symmetry breaking observables are also discussed. 
Kim Maltman and T. Goldman