Ap. Szczepaniak et Es. Swanson, Chiral extrapolation, renormalization, and the viability of the quark model - art. no. 072001, PHYS REV L, 8707(7), 2001, pp. 2001
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.