Dynamical selection rules in [formula omitted]p annihilation at rest

Abstract

The branching ratios for p p annihilation at rest into two mesons show the existence of dynamical selection rules. The ratios for some annihilation modes are small even though much larger rates should be expected on the basis of statistical models. Dynamical selection rules are observed in annihilations in which strange mesons are produced, and in annihilations into two isovector mesons. The selection rules seem - to first order - not to depend on the spins or orbital angular momenta of the p p atom or of the two mesons produced. This observation suggests an underlying symmetry. It is argued that this symmetry is SU(3).