2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/104542A phenomenological analysis of various decay processes is performed in order to test the large $N_c$ Chiral Perturbation Theory predictions for the octet and singlet pseudoscalar decay constants and mixing angles. The results obtained hint at a disagreement with the expectations of this theoretical framework although the statistical significance is still limited.7 pages, uses appolb style. Talk presented at the PHOTON2005 International Conference on the Structure and Interactions of the Photon, Warsaw, Poland, 31.8-4.9.2005High Energy Physics - Phenomenologytext