ABSTRACT
An important application of the addition of a spin ½ and an orbital angular momentum is in the theory of the scattering of a spinless particle by a spin ½ particle, for example, the scattering of a p mason, which has spin zero, by a proton. The orbital angular momentum is the relative angular momentum of the proton and pion, and the spin ½ is that of the proton. A simple example of the addition of three angular momenta is in a proton-neutron system. The proton and neutron each have a spin ½ and the third angular momentum is their relative orbital angular momentum. The Clebsch-Gordan coefficients obey simple orthogonality relations. An important application of the addition of a spin ½ and an orbital angular momentum is in the theory of the scattering of a spinless particle by a spin ½ particles, for example, the scattering of a p meson, which has spin zero, by a proton.
