Glory scattering in strong-field ionization

Since Keldysh's pioneering work fifty years ago, the theory of strong-field approximation has achieved great success in providing a solid foundation to strong-field atomic ionization. However, the neglect of Coulomb interaction remains a long-standing gap between the well-established optical-tunneling picture and the experimental observations, which has been highlighted in the past decade by a series of striking disagreements extending from the low energy regime near the ionization threshold to the intermediate energy around twice the ponderomotive energy, not only in longitudinal direction but also transverse direction. Here we report that the gap can be largely bridged with the aid of an effect named as glory, which is associated with a specific type of singularity concealed in Coulomb forward rescattering. We reveal that the trajectory lying exactly on the singular point dominates both the photoelectron longitudinal and transverse momentum distribution, which directly connects tunneling theory with photoelectron distribution after post-tunneling propagation.