Gaussian Sum-Rules and Prediction of Resonance Properties

Techniques for using Gaussian QCD sum-rules to predict hadronic resonance properties are developed for single-resonance and two-resonance phenomenological models, and criteria are developed for determining which of these models is required for analyzing a particular hadronic channel. The vector current sum-rule coupled to the ρ meson is shown to be consistent with a single resonance model, and the Gaussian sum-rule analysis results in an accurate ρ mass prediction which exhibits excellent agreement between the theoretical prediction of the Gaussian sum-rule and the phenomenological model. A two-resonance model is shown to be necessary for the Gaussian sum-rule for the non-strange quark scalar (n̄n) currents. The two-resonance Gaussian sum-rule analysis of the isoscalar and isovector (I = 0, 1) n̄n scalar mesons exhibits excellent agreement between the theoretical prediction and phenomenological model. The prediction of the resonance properties of the I = 0, 1 n̄n scalar mesons in this two-resonance model provides valuable information for the interpretation of the scalar mesons, including the X(1775).