Isoscalarππresonances and current-algebra constraints inψ′→ψ+2π

Abstract

The difficulty of classifying three $I=0$, low-lying scalar resonances [in particular $\ensuremath{\epsilon}(700)$] within an SU(4) framework is stressed. Current-algebra constraints are worked out for the decay ${\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}\ensuremath{\psi}+2\ensuremath{\pi}$; these lead to a matrix element disfavoring small pion momenta. A companion discussion is given of the decays ${\ensuremath{\eta}}^{\ensuremath{'}}=\ensuremath{\eta}\ensuremath{\pi}\ensuremath{\pi}$ and ${\ensuremath{\omega}}^{\ensuremath{'}}=\ensuremath{\omega}\ensuremath{\pi}\ensuremath{\pi}$.