VIRTUALITIES OF QUARKS AND GLUONS IN A QCD VACUUM AND NONLOCAL CONDENSATES WITHIN THE SINGLE INSTANTON APPROXIMATION

We calculate the lowest-dimensional nonlocal quark and gluon condensat es within the single instanton approximation of the instanton liquid m odel. As a result, we determine the values of average virtualities of quarks lambda(q)(2) = [:(q) over bar D(2)q:]/[:<(qq)over bar>:] and gl uons lambda(g)(2) = [:G (D) over tilde(2)G:]/[:GG:] in the QCD vacuum and obtain parameterless predictions for the ratio lambda(g)(2)/lambda (g)(2) = 12/5, and for some ratios of different vacuum condensates of higher dimensions. The nonlocal properties of quark and gluon condensa tes are analyzed, and the insufficiency of the single instanton approx imation is discussed.