Hadronic transitions among quarkonium states in a soft-exchange-approximation. Chiral breaking and spin symmetry breaking processes☆

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′ → 3Pπ0, 3Pη, level splittings and transitions which break both chiral and spin symmery, such as ψ′ → J/ψπ0, J/ψη and 1P1 → J/ψπ0.