2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/44662In pure chiral perturbation theory (ChPT) the couplings of higher order Lagrangian terms are running parameters and hence can be determined only empirically from various low-energy hadronic processes. While this scenario works well for strong interactions, it is unsatisfactory for nonleptonic and radiative nonleptonic weak interactions: It is impossible, from the outset, to determine all unknown higher-order chiral couplings by experiment; theory is tested only by certain chiral constraints rather than by its quantitative predictions. Based on a QCD-motivated model for $p^4$ strong chiral Lagrangian valid in the limit of large $N_c$, one can derive large-$N_c$ fourth-order effective chiral Lagrangians for $ΔS=1$ nonleptonic weak interactions and radiative weak transitions. Applications to $K\riπππ,~K\riπγγ$, and $K\riππγ$ are discussed.15 pages (input of phyzzx.tex is required), IP-ASTP-17-92High Energy Physics - Phenomenologytext