Meson spectroscopy in the quark shell model

The meson spectrum is discussed in terms of the three-quark shell model with SU(6) X O(3) symmetry. Wave functions and mass operators are constructed. A fit of the experimental spectrum is performed for the N = 0 and 1 levels, and gives good argeement with the data. An accetable fit to the N = 1 level is not possible with only spin-scalar and spin-vector operators, but the inclusion of a particular spin-tensor gives a good description of the spectrum and a successful prediction of mixing angles. The possibility that the low-lying 0+ states are (qq) (anti qanti q) bound states, as suggested in the bag model, requires a separate (anti q) nonet at higher mass. The consequences of this view have been investigated by refitting the mass spectrum with the conventional 0+ states replaced by recently discovered higher mass mesons. In this case too, spin-tensor terms are needed to obtain a reasonable fit to the data. Due to a lack of data no complete analysis for the N = 2 level can be made, but by exploiting a relation between reduced matrix-elements for different multiplets, the masses of several resonances are predicted. (Auth.)