Robust transverse structures in rescattered photoelectron wavepackets and their observable consequences

Initial-state symmetry has been underappreciated in strong-field spectroscopies, where laser fields dominate the dynamics. We demonstrate numerically that the transverse photoelectron phase structure, arising from this symmetry, is robust in strong-field rescattering, and manifests in strong-field photoelectron spectra. Interpretation of rescattering experiments need to take these symmetry effects into account. In turn, transverse photoelectron phase structures may enable attosecond super-resolution imaging with structured electron beams.