COMPARISON OF CHIRAL PERTURBATION-THEORY AND QCD SUM-RULE RESULTS FORPSEUDOSCALAR ISOSCALAR-ISOVECTOR MIXING

The forms of the neutral, non-strange pseudoscalar propagator matrix a nd mixed axial current correlator, (0/T(A(mu)(3)A(nu)(8))/0), are disc ussed at next-to-leading (one-loop) order in chiral perturbation theor y, and the results compared to those obtained using QCD sum rules. Thi s comparison provides a check of the truncations employed in the sum r ule treatment of the current correlator. Values for the slope of the c orrelator with q(2) in the two approaches are found to differ by more than an order of magnitude and the source of this discrepancy is shown to be the incorrect chiral behavior of the sum rule result.