2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/129601We briefly review the derivation of a non-relativistic quantum mechanics description of a weakly bound non-relativistic system from the underlying quantum field theory. We highlight the main techniques used.4 pages, 6 figures. Invited talk given at 42nd Rencontres de Moriond on QCD and High-Energy Hadronic Interactions, La Thuile, March 2007High Energy Physics - Phenomenologytext