QCD sum rules: charmonium

The dimensiond=4 gluon condensateφ ₁ is determined from an analysis of charmonium, taking model dependent estimates ofd=6.8 condensates into account. ForS-waves, there is a compatibility region, where both these and model dependent higher state corrections to ground state dominance are small, enablingφ ₁ to be determined from a fit to the data. ForP-waves the estimated higher dimension contributions are large in the region of ground state dominance, and noφ ₁ determination is possible. Theφ ₁ value obtained from the fit to theS-wave ratios is 3 5 times bigger than that obtained by RRY using the plateau method. The methods are compared for the vector current. We show that the higher state correction used by RRY does not fit the data; and that the plateau method is much more sensitive to thed=6.8 condensates than the ratio used here. When reasonable estimates of both these and the higher state corrections are taken into account, there is compatibility between the two methods.