The theory of KL → ππ decays
In this chapter, we present theoretical expectations for various CP violating observables in K → ππ decays, where we must face up to the challenge of explaining the ΔI = 1/2 rule discussed in Section 5.3. A theoretical description of decay rates involves two main steps:
Below we mainly state the results on operator renormalization and on the size of the relevant matrix elements giving few explanations. A more detailed treatment is found in .
9.1 The ΔS = 1 non-leptonic Lagrangian
The electroweak Lagrangian given in Eq. (8.17) is defined at an energy scale MW. At lower scales the