Kaon nonleptonic decays and chiral-symmetry breaking

Abstract

A consistent formulation of current algebra and pion partial conservation of axial-vector current is given for the kaon nonleptonic weak decays $K\ensuremath{\rightarrow}2\ensuremath{\pi}$ and $K\ensuremath{\rightarrow}3\ensuremath{\pi}$. This includes evaluation of kaon $\ensuremath{\sigma}$ terms and $\ensuremath{\Delta}I=\frac{1}{2}$ and $\ensuremath{\Delta}I=\frac{3}{2}$ contributions to the weak current-current Hamiltonian. A large meson $\ensuremath{\sigma}$ term, ${\ensuremath{\sigma}}_{\mathrm{KK}}\ensuremath{\sim}2{{m}_{\ensuremath{\pi}}}^{2}$, apparently is necessary to explain the ${K}_{2\ensuremath{\pi}}$ and ${K}_{3\ensuremath{\pi}}$ measured decay parameters. The hyperon nonleptonic decays are then reexamined and also shown to be compatible with a large value for ${\ensuremath{\sigma}}_{\mathrm{KK}}$. Implications for the (3,\ifmmode\bar\else\textasciimacron\fi{}3) chiral-symmetry-breaking model and for octet dominance of the weak Hamiltonian are then discussed.