Chiral extrapolation, renormalization, and the viability of the quark model - art. no. 072001

The relationship of the quark model to the known chiral properties of QCD i s a long-standing problem in the interpretation of low-energy QCD. In parti cular, how can the pion be viewed as both a collective Goldstone-boson quas iparticle and as a valence-quark-antiquark bound state? A comparison of the many-body solution of a simplified model of QCD to the constituent-quark m odel demonstrates that the quark model is sufficiently flexible to describe meson hyperfine splitting provided proper renormalization conditions and c orrect degrees of freedom are employed consistently.