2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/45356The branching ratios of weak decays of $η$ mesons are estimated in the framework of the Standard Model. To observe such decays, $η$ meson sources with $N_η > 10^{13}$ per year are needed.6 pages, LaTeX file, A postscript version can be obtained from anonymous ftp at ftp://ftp.ifae.es/preprint.ftHigh Energy Physics - Phenomenologytext