The influence of nondipole terms on the time delay in photoionization by an extreme-ultraviolet attosecond pulse in the presence of a near-infrared femtosecond laser pulse from 1s, 2s, and 2p states in hydrogen is investigated. In this attosecond photoelectron streaking process, the relative importance of nondipole terms compared with the dipole term is varied in two ways: (i) by increasing the photon energy of the attosecond pulse, and (ii) by considering photoelectron emission in directions where the dipole contribution is suppressed due to symmetry. Even in these cases, no time delay due to nondipole terms is found. The numerical calculations are supported by a theoretical analysis of the time delay.
Physical Review a (atomic, Molecular and Optical Physics), 2012, Vol 86, Issue 4