Some Consequences of Symmetries of the Strong Interactions

Abstract

The consequences for the electromagnetic interactions of strange particles of some proposed symmetries of the strong interactions are discussed. A minimal electromagnetic coupling is assumed. It is shown that if the interactions with both $\pi$ and $K$ mesons of the nucleon and cascade particle are identical, if one neglects the $n-\Xi$ mass difference, and if charge independence is satisfied, then the electromagnetic from factors of the ${\Lambda }^0$ and ${\Sigma }^0$, and in particular their magnetic moments, vanish. This is independent of any assumed relation between the $\Lambda$ and $\Sigma$ interactions, such as global symmetry. It is also shown that the same conditions, together with charge conjugation invariance, imply a generalized form of the Pais-Jost-Pugh theorem about processes involving only meson or photon external lines. If there is still more symmetry for the strong interactions, as in the case where the $\pi$ interactions are globally symmetric and the $K$ interactions also have this doublet structure, it is shown that the $K^0$ acts as a completely neutral particle insofar as electromagnetic interactions are concerned.