QCD and Nuclear Structure

Abstract

Conventional nuclear theory — i.e. visionalizing the nucleus as a bound system of nucleons — is hampered by severe difficulties. They are mainly due to the unavoidable phenomenological character of the expressions for nuclear forces. Even within the well known boson theoretical attempt (so called boson exchange) which so far represents the most common approach, phenomenological parameters represent a basic input (e.g. various coupling constants and a most important cut-off or formfactor). In view of this unpleasant Situation the transition from this nucleonic level to an over-all nuclear quark structure represents, in fact, a real revelation: For the first time within the long and tedious history of nuclear science the expression for the basic interaction between the elementary constituents, i.e. the quarks, appears completely deter- mined by a (geometrically) most natural and fundamental theory namely QCD based, in turn, on the ail-embracing local gauge principle. In other words: Half phenomenological boson exchange appears by now replaced by gluon exchange, i.e. the quanta of the SU(3) gauge field, which, in turn, is uniquely determined by the basic local invariance principle of the theory. In this extremely short and informal report it will be shown within the framework of two different examples, how conventional models may be reinterpreted, or, replaced by using this more basic viewpoint: We first consider the few nucleon systems to be followed — as the main point — by a quark and gauge theoretical reformulation of conventional nuclear shell structure.