Quark-composites approach to QCD: The nucleon-pion system - art. no. 074009

We present a new perturbative approach to QCD, based on the use of quark co mposites as fundamental variables. The composites with the quantum numbers of the nucleons are assumed as new integration variables in the Berezin int egral which defines the partition function, while the composites with the q uantum numbers of the chiral mesons are replaced by auxiliary bosonic field s. The action is modified by the addition of irrelevant operators which pro vide the kinetic terms for these composites, and the quark action is treate d as a perturbation. The resulting expansion has the quark confinement buil t in. As a first application we investigate the pion-nucleon interaction. [ S0556-2821(99)01615-X].