Hadronic Transitions among Quarkonium States in a Soft-Exchange-Approximation. Chiral Breaking and Spin Symmetry Breaking Processes

Abstract

Although no asymptotic heavy quark spin symmetry, and even more no flavor symmetry, are expected for systems such as quarkonium, a numerical discussion shows that for some processes and in a preasymptotic region which may roughly include charmonium and bottomonium, the use of the spin-symmetry may be useful in conjunction with chiral symmetry for light hadrons (soft-exchange- approximation regime, SEA). We continue our discussion of hadronic transitions in the SEA-regime by studying in particular chiral breaking transitions such as $~^3P' \to ~^3P\pi^0$, $~^3P\eta$, level splittings and transitions which break both chiral and spin symmetry, such as $\psi ' \to J/\psi \pi^0$, $J/\psi \eta$, and $~^1P_1 \to J/\psi \pi^0$.