Effective weak chiral Lagrangian to O(p4) in the chiral quark model Original Research Article

We investigate the ΔS=1,2 effective weak chiral Lagrangian within the framework of the chiral quark model. Starting from the effective four-quark operators, we derive the effective weak chiral action by integrating out the constituent quark fields. Employing the derivative expansion, we obtain the effective weak chiral Lagrangian to order O(p4). We examine the contributions of the order O(Nc) to the ratio g8/g27, considering e.g. the quark axial-vector constant gA different from unity. The low energy constants of the counterterms are also presented and discussed.