2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/192504We calculated the mass and width of the $d'$ resonance inside nuclei within a nucleon-$Δ$ model by including the self-energy of the $Δ$ in the $NΔ$ propagator. We found that in the nuclear medium the width of the $d'$ is increased by one order of magnitude while its mass changes only by a few MeV. This broadening of the width of the $d'$ resonance embedded in nuclei is consistent with the experimental observations so that the $d'$ can be understood as a $NΔ$ resonance. Thus, given the freedom between either isospin 0 or isospin 2 for the $d'$, our results give weigth to the isospin-2 assignment.14 pages, RevteX type, 2 eps figures. To be published in Phys. Rev. C (September)Nuclear Theorytext