On the stability of QED and QCD

The QED and QCD vacuum energy in a selfdual field with constant strength is considered. It is shown that in the quantum electrodynamics of a system of charged fermion and boson fields the minimum of vacuum energy is realized with zero selfdual photon field if (1) the doubled number of fermions exceeds the number of bosons and (2) the lightest charged particles are fermions. Namely, this situation takes place in Nature. In the quantum chromodynamics the global stability of the quark-gluon system takes place if the number of quarks with different flavours is equal to or more than two. The existence of massless selfinteracting gluons leads to the QCD vacuum which can be realized with nonzero selfdual gluon fields, The result is the confinement of quarks and gluons and the origin of stable states - hadrons. (author)