## Instantons and Meson Correlators in QCD

Author: Marcus Hutter
Comments: 43 latex pages, 7 1/2 figures included by epsf.tex-macro
Report-no: LMU-Muenchen HEP-93-18
Journal-ref: Z.Phys. C74 (1997) 131-143

Abstract: Various QCD correlators are calculated in the instanton liquid model in zeromode approximation and $1/N_c$ expansion. Previous works are extended by including dynamical quark loops. In contrast to the original "perturbative" $1/N_c$ expansion not all quark loops are suppressed. In the flavor singlet meson correlators a chain of quark bubbles survives the $N_c\to\infty$ limit causing a massive $\eta^\prime$ in the pseudoscalar correlator while keeping massless pions in the triplet correlator. The correlators are plotted and meson masses and couplings are obtained from a spectral fit. They are compared to the values obtained from numerical studies of the instanton liquid and to experimental results.