Study of Kaon Decay to Two Pions

Understand

The weak decay of the kaon to two pions is studied within the NJL Model.

• Using the standard effective weak Hamiltonian, both the decay amplitude arising from an intermediate state \sigma-meson and the direct decay amplitude are calculated.
• The effect of final state interactions is also included.
• When the matching scale is chosen such that the decay amplitude with isospin I=2 is close to its experimental value, the \sigma-meson contributes more than 85% of the total I=0 amplitude.