Spin independence, W spin, parity, and SU(6) symmetry

Abstract

The assumption of strict spin independence of strong interactions between elementary particles forbids all three-meson and meson-baryon-baryon couplings, such as ρππ, NNπ, and N*Nπ. It is shown that these catastrophies may be avoided, even in the nonrelativistic limit, by adopting a modified definition of spin independence, i.e., W-spin independence. A nonrelativistic definition of W spin is obtained which requires only a trivial change to yield the relativistic description. The consequences of the assumption of W-spin independence are explored.