Pocket resonances in low-energy antineutron reactions with nuclei

Upon investigating whether the antineutron-nucleus annihilation cross-sections at very low momenta p satisfy Bethe-Landau's power law of σann(p)∝1/pα, we uncover unexpected regular oscillatory structures in the low antineutron energy region from 0.001 to 10 MeV, with small amplitudes and narrow periodicity in the logarithm of the antineutron energies, for large-A nuclei such as Pb and Ag. Subsequent semiclassical analyses of the S matrices reveal that these oscillations are pocket resonances that arise from quasi-bound states inside the effective potential pocket with a barrier. They are a continuation of the bound states in the continuum. Experimental observations of these pocket resonances will provide vital information on the properties of the optical model potentials and the nature of the antinucleon-nucleus reactions.