The quark-composites approach to QCD: The nucleons

We present a new perturbative approach to QCD based on the use of quark composites with hadronic quantum numbers as fundamental variables. We apply it to the case of the nucleons by performing a nonlinear change of variables in the Berezin integral which defines the partition function of QCD. The nucleon composites are thereby assumed as new integration variables. We evaluate the jacobian and certain transformation functions which appear in the change of variables. We show that the free action of the nucleon composites is the Dirac action, and we evaluate the first perturbative contributions to their electroweak effective action, which turn out to be a pure renormalization. Our expansion is compatible with a perturbative as well as nonperturbative regime of the gluons and it has the characteristic feature that the confinement of the quarks is buit in.