Scalar Mesons, Glueballs, Instantons and the Glueball/Sigma

Abstract

We include instanton effects in QCD sum rules for coupled scalar glueballs and mesons. We find a light glueball/sigma as in earlier studies without instantons, but in a lattice-type pure instanton model the light glueball/sigma is not found. In the 1-2 Gev region we now find that lightest I=0 meson, in the region of the f${}_o$(1370), has no direct glueball mixing, with the instanton loop replacing the glueball component. The lightest scalar mainly glueball in the region of the f${}_o$(1500) is sensitive to the choice of nonperturbative gluonic parameters.

Comments: 12 pages, 4 figures