An introduction to the quark model

Few-charge systems History of the quark model Mesons Baryons Multiquarks and other exotics Outlook
Molecules
We learned to be careful in this sector
In 1975, Iwazaki suggested ψ ′ = (c¯cq¯q)
In 1976–77, Voloshin & Okun, and De Rujùla, Georgi & Glashow
molecular structures out of D (∗) and ¯ D (∗)
In particular, DGG were puzzled by ψ(4.04) decaying too often in
D ∗ ¯ D ∗ relative to D ¯ D and D ¯ D ∗ + c.c., as compared to spin
counting and phase-space.
But Le Yaouanc et al., and Eichten et al. have shown this was
due to the node structure of this state.
We were accustomed to orbital excitations (Regge trajectories),
less to radial excitations
JMR Quark Model