The finite-width Laplace sum rules for the 0++ scalar glueball in the instanton liquid model

Abstract

In the framework of a semiclassical expansion for quantum chromodynamics (QCD) in the instanton liquid background, the correlation function of the 0++ scalar glueball current is given. Besides the pure classical and quantum contributions, the contributions arising from the interactions between the classical instanton fields and quantum gluons are taken into account as well. Instead of the usual zero-width approximation for the resonance, the Breit–Wigner form for the spectral function of the finite-width resonance is adopted. The family of the Laplace sum rules for the scalar glueball in QCD with and without light quarks are studied. A consistency between the subtracted and unsubtracted sum rules is very well justified, and the values of the mass, decay width and the coupling to the corresponding current for the 0++ resonance in which the glueball fraction is dominant, are obtained.