Relativistic bound states

The standard results of the quark model rely on nonrelativistic descriptions of the wavefunctions of the quarks in the hadron. However, simple uncertainty principle considerations show that the momenta of the quarks are comparable to their (constituent) masses, so that relativistic dynamics must be used in the description of the hadronic structure. In this paper the author describes a number of new and old results which illustrate relativistic effects on the quark structure of hadrons, and which employ the method of light cone quantisation to handle relativity. This approach to e-e- scattering immediately generalises, of course to e+e- scattering and the kernel for the Bethe-Salpeter equation for positronium. It is well known (e.g. Itzykson and Zuber 1980) that the Bethe-Salpeter equation is solved starting from Fock's solution for the momentum space wavefunction of two particles interacting through a Coulomb potential. The light cone treatment suggests that the Bethe-Salpeter equation with the contact inteaction of equation as the kernel may be an alternative starting point. 17 refs., 2 figs