2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/100685This paper is withdrawn by the authors, a better version is available as hep-ph/0505139.This paper is withdrawn by the authors, a better version is available as hep-ph/0505139High Energy Physics - PhenomenologyDensity dependence of pion coupling, $f_π$, from three modelstext