$K\to 2\pi$ Decay in the Nambu-Jona-Lasinio Model

Abstract

We study the $K\to 2\pi$ decays using the $U_L(3)\times U_R(3)$ version of the Nambu-Jona-Lasinio model with the effective $\Delta S=1$ nonleptonic weak interaction. The $\Delta I=3/2$ amplitude is in reasonable agreement with experimental data. On the other hand, the calculated $\Delta I=1/2$ amplitudes strongly depend on the mass of the low-lying scalar-isoscalar $\sigma$ meson, and therefore give a strong constraint on the parameters of the model.

Comments: 10 pages, 3 Postscript figures, Talk given at YITP Workshp: From Hadronic Matter to Quark Matter: Evolving View of Hadronic Matter, Kyoto, Japan, Oct. 30-Nov. 1, 1994, to be published in Prog. Theor. Phys. Suppl