  Non-dipole effects in strong-field photoelectron momentum spectra have been
revealed experimentally [C.T.L. Smeenk et al., Phys. Rev. Lett. 106, 193002
(2011); A. Ludwig et al., Phys. Rev. Lett. 113, 243001 (2014)]. For certain
laser parameters and photoelectron momenta the spectra were found to be shifted
against the laser propagation direction whereas one would naively assume that
the radiation pressure due to the $\vec{v}\times\vec{B}$-force pushes electrons
always in propagation direction. Only the interplay between Lorentz and Coulomb
force may give rise to such counterintuitive dynamics. In this work, we
calculate the momentum-dependent shift in and against the propagation direction
by extending the quantum trajectory-based Coulomb-corrected strong-field
approximation beyond the dipole approximation. A semi-analytical treatment
where both magnetic and Coulomb force are treated perturbatively but
simultaneously reproduces the results from the full numerical solution of the
equations of motion.
