The Mixed-Isospin Vector Current Correlator in Chiral Perturbation Theory and QCD Sum Rules ADP-95-20/T179 hep-ph/9504237

The mixed-isospin vector current correlator, 〈0|T (V ρ μ V ω ν )|0〉 is evaluated using both QCD sum rules and Chiral Perturbation Theory (ChPT) to one-loop order. The sum rule treatment is a modification of previous analyses necessitated by the observation that those analyses produce forms of the correlator that fail to be dominated, near q2 = 0, by the most nearby singularities. Inclusion of contributions associated with the φ meson rectify this problem. The resulting sum rule fit provides evidence for a significant direct ω → ππ coupling contribution in e+e− → π+π−. It is also pointed out that results for the q2-dependence of the correlator cannot be used to provide information about the (off-shell) q2-dependence of the off-diagonal element of the vector meson propagator unless a very specific choice of interpolating fields for the vector mesons is made. The results for the value of the correlator near q2 = 0 in ChPT are shown to be more than an order of magnitude smaller than those extracted from the sum rule analysis and the reasons why this suggests slow