2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/82081A renormalized three-body model with zero-range potential is used to estimate the mean-square radii of three-body halo nuclei and molecular systems. The halo nuclei ($^6$He, $^{11}$Li, $^{14}$Be and $^{20}$C) are described as point-like inert cores and two neutrons. The molecular systems, with two helium atoms, are of the type $^4$He$_2-$X, where X$=^4$He, $^6$Li, $^7$Li, or $^{23}$Na. The estimations are compared with experimental data and realistic results.Parallel talk at 17th International IUPAP Conference on Few-Body Problems in Physics, June 5-10, 2003, Durham, North Carolina, USANuclear TheoryCondensed MatterAtomic and Molecular Clusterstext