The Meson as a Composite Particle

Calculations are carried out along the lines of the work of Fermi and Yang in which the π-meson is considered as a composite particle formed from a proton and an anti-neutron. On the assumption of a vector interaction it is found that the ¹S₀ state must be excluded because its energy goes to zero as the interaction goes to zero, while the ³P₀ state appears to give an acceptable solution. On the assumption of a tensor interaction it is found that ¹S₀ and ³P₀ solutions both exist, but for opposite signs of the interaction. The tensor interaction must therefore be excluded since it would lead to the formation of a composite particle by a proton and a neutron. Using the vector interaction one finds that the ground state is a ³P₁, but that there are other states with j=0,1 and 2 lying near it, the proximity depending on the interaction range assumed.