2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/193223In this work we study the spectral functions of scalar mesons in one- and two-channel cases. When the propagators satisfy the Källen-Lehman representation a normalized spectral function is obtained, allowing to take into account finite-width effects in the evaluation of decay rates. In the one-channel case, suitable to the light sigma and k mesons, the spectral function can deviate consistently from a Breit-Wigner shape. In the two-channel case with one subthreshold channel the evaluated spectral function is well approximated by a Flatte' distribution; when applying the study to the a_0(980) and f_0(980) mesons the tree-level forbidden KK decay is analysed.13 pages, 7 figuresHigh Energy Physics - Phenomenologytext