Symmetries in the nonlinear Bethe-Heitler process

The nonlinear Bethe-Heitler process in a bichromatic laser field is investigated using strong-field quantum electrodynamics formalism. The symmetry properties of the angular distributions of the created e(-)e(+) pairs are analyzed. These properties are shown to be governed by a behavior of the vector potential characterizing the laser field, rather than by the respective electric-field component.