2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/86050The generation of finite energy packets of X-waves is analysed in normally dispersive cubic media by using an X-wave expansion. The 3D nonlinear Schroedinger model is reduced to a 1D equation with anomalous dispersion. Pulse splitting and beam replenishment as observed in experiments with water and Kerr media are explained in terms of a higher order breathing soliton. The results presented also hold in periodic media and Bose-condensed gases.18 pages, 6 figures, corrected version to be published in Physical Review EOpticsGeneral Physicstext