Instanton and Higher-Loop Perturbative Contributions to the QCD Sum-Rule Analysis of Pseudoscalar Gluonium

Abstract

Instanton effects and three-loop perturbative contributions are incorporated into QCD sum-rule analyses of pseudoscalar ($J^{PC}=0^{-+}$) gluonium. Gaussian sum-rules are shown to be superior to Laplace sum-rules in optimized predictions for pseudoscalar gluonium states in the presence of instanton contributions. The Gaussian sum-rule analysis yields a pseudoscalar mass of $(2.65\pm 0.33)GeV$ and width bounded by $\Gamma <530MeV$. The Laplace sum-rules provide corroborating evidence in support of the $\approx 2.7GeV$ mass scale.

Comments: latex, using elsart style and amsmath, 17 pages, 6 eps figures included in manuscript. Revised version includes an extra figure and extends the analysis to consider the coupling of the eta'