Meson spectroscopy

Abstract
The experimentally observed meson spectrum is compared to that predicted by theoretical models. The discussion and interpretation is dominated by the nonrelativistic quark model, although other theoretical ideas have some bearing on particular aspects of the spectrum. In the quark model, mesons are envisaged as compounds of a quark and an antiquark where the quarks are assigned to the smallest non-trivial multiplet of the symmetry group SU(3)-a triplet. Particles are then classified according to symmetries involving both their internal SU(3) quantum numbers-isospin and strangeness-and the ordinary non-relativistic spin assumed for their quark constituents. With a growing body of experimental support, it becomes increasingly urgent to achieve a fully consistent theory of quark confinement and bound states.