2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/87803An interpretation of the ``halo puzzle'' in accelerators based on quantum-like diffraction is given. Comparison between this approach and the others based on classical mechanics equations is exhibited.6 pages. To appear in Proceedings of the 1999 Particle Accelerator Conference (PAC99), 29 March -- 02 April 1999, New York City, Eds: A. Luccio and W. MacKay. http://www.pd.infn.it/~khan/ and http://www.pd.infn.it/~pusterla/Accelerator PhysicsOpticsQuantum Physicstext