Quasi-bound low energy tail of resonance

The ground state of particle-unbound nuclei is observed as a resonance. According to the Heisenberg's uncertainty principle, the shorter is the lifetime of the state the broader is the resonance. The Breit-Wigner formalism describes perfectly the shape of the resonance when energy-dependent partial-widths are used. In the low energy tail of a ground state resonance near the particle-emission threshold, the partial-width for the emission of a charged particle through the Coulomb barrier is drastically reduced. The fact that the proton decay is strongly hindered seems to be equivalent to the assertion that the decay of the proton is strongly delayed. In this interpretation and as an example, possible consequences are discussed in astrophysical context. Two reactions O(p,β)O and O(p,γ)(β)O are proposed as new pathways to bypass the O waiting point. Cross-sections were calculated after precise measurements of energies and widths of the proton-unbound F low lying states, obtained using the H( O,p)O reaction. These measurements were performed at SPIRAL - GANIL facility using an O post-accelerated radioactive beam. © 2007 American Institute of Physics.