  We apply to lattice QCD a bosonization method previously developed in which
dynamical bosons are generated by time-dependent Bogoliubov transformations.
The transformed action can be studied by an expansion in the inverse of the
nilpotency index, which is the number of fermionic states in the structure
function of composite bosons. When this number diverges the model is solved by
the saddle point method which has a variational interpretation. We give a
stationary covariant solution for a background matter field whose fluctuations
describe mesons. In the saddle point approximations live fermionic
quasiparticles with quark quantum numbers which are confined, in the sense that
they propagate only in pointlike color singlets. Conditions for chiral symmetry
breaking are determined, to be studied numerically, and a derivation of
mesons-nucleons action is outlined.
