Coherent polychotomous waves from an attractive well
  A novel effect of a wave packet scattering off an attractive one- dimensional well is found numerically and analytically. For a wave packet narrower than the width of the well, the scattering proceeds through a quasi-bound state of almost zero energy. The wave reflected from the well is a polychotomous (multiple peak) monochromatic and coherent train. The transmitted wave is a spreading smooth wave packet. The effect is strong for low average speeds of the packet, and it disappears for wide packets. 
G. K\"albermann (Cyclotron Institute, Texas A&M University College   Station, TX, USA)