Narrow near-threshold resonances of the hydrogen atom in strong magnetic fields

Continuum states and bound states of the hydrogen atom in a strong magnetic field are studied for field strengths somewhat smaller than B₀=2.35×10⁹ G, and for azimuthal quantum numbers up to | m |=2. At field strengths for which the third Landau excited state in a given m^π subspace with positive z parity π lies close to the ionization threshold, the width of this state is orders of magnitude smaller than might be expected from the widths of the two lower-lying Landau excited states in the respective m⁺ subspace.