METHODS OF CALCULATION OF HIGHER POWER CORRECTIONS IN QCD

Although the methods of calculation of power corrections in QCD sum ru les are well known, algebraic complexity rapidly grows with the increa se of vacuum condensates' dimensions. Currently, state-of-the-art calc ulations include dimension 7 and 8 condensates. I summarize and extend algorithms of such calculations. First, I present all the formulae ne cessary for application of the systematic classification of bilinear q uark condensates proposed earlier, and extend this method to the case of gluon condensates. Then I apply these systematic procedures to expa nsions of bilinear and noncollinear quark and gluon condensates in loc al ones, and of noncollinear condensates in bifocal ones. The formulae obtained can be used for calculation of correlators involving nonloca l condensates, and for inventing consistent ansatze for these condensa tes. Finally, I summarize the methods of calculation of heavy and ligh t quark currents' correlators. This paper aims both to present new res ults on gluon and nonlocal condensates and to be a self-contained hand book of formulae necessary for calculation of power corrections in QCD sum rules.