Constituent Quarks from QCD: Perturbation Theory and the Infra-red

Abstract

Systematic approaches to building up gauge invariant descriptions of charged fields, such as electrons or quarks, are described. Physically relevant descriptions must then be singled out from a multiplicity of possibilities and to this end we give a physical interpretation of one description. Perturbative calculations which back up this interpretation are outlined. A non-perturbative obstruction to observing an isolated quark is reported. This sets the limits of the constituent quark model.

3 pages, sprocl.sty required, talk given at the International Conference "Quark Confinement and the Hadron Spectrum II", Como June 1996, A related simulation may be found at http://www.ifae.es/~roy/