ILM gluons in perturbative QCD

Abstract

In this paper we extend our previous work on gluon propagator in the Instanton Liquid Model (ILM) of the QCD vacuum. This objects presents a lot of interest for studies of the heavy quarkonium $Q\bar Q$ observables in the framework of potential Nonrelativistic QCD (pNRQCD). Our goal is to evaluate the gluon polarization operator in ILM, and understand if it gets contributions from infrared (IR) renormalons. We perform a systematic analyis, taking into account both perturbative and nonperturbative effects, and making a double series expansion in terms of the strong coupling $\alpha_s(\rho)\sim 0.5$ (the scale is given by average instanton size $\rho\approx1/3$ fm) and the instanton gas packing fraction $\lambda=\rho^4/R^4\sim 0.01$ ($R\approx 1$ fm is average inter-instanton distance). We demonstrate that there are no IR renormalon related to ILM gluon propagator, since instantons generate a ILM gluon dynamical mass.