Using $K^0{\pi }^{-}\to {\pi }^{-}$ transitions to compute $K\to (\pi \pi {)}_{I=0}$ decay amplitudes at NLO in the chiral expansion

Changhoan Kim, Christopher Sachrajda

It is proposed to compute matrix elements for the (unphysical) $K^0{\pi }^{-}\to {\pi }^{-}$ transition to determine the next-to-leading order low energy constants of the weak chiral Lagrangian.…