us to describe in detail how the wavepacket trajectory evolves in the LHMs. Recently, the technique of transformation optics has emerged as a means of designing metamaterials that can bring about unprecedented control of electromagnetic fields [46]. It is possible that the trajectories of circularly polarized wavepacket can be controlled by introducing a prescribed spatial variation in the constitutive parameters. In conclusion, we have established a general vector field model to describe the role of transverse momentum currents in optical Magnus effect in the free space. We have demon- strated the existence of a novel optical polarization-dependent Magnus effect which differs from conventional optical Magnus effect in that light-matter interaction is not required. In the optical Magnus effect, the circularly polarized wavepacket acts as the rotating ball, but is not identical to a rigid body. This is because different parts of the wavepacket present diverse rotation characteristics. For a certain circularly polarized wavepacket, whether the rotation is clockwise or anticlockwise depends on the polarization state. Such a polarization- dependent rotation is unavoidable when the wavepacket possesses transverse momentum currents. We predict that this novel effect may be observed experimentally even in the propagation direction. Our findings provide further evidence for the optical Magnus effect in the free space. Because of the close similarity in atom physics, condensed matter, and optical physics, we believe that the Magnus effect is not limited to electromagnetic fields, but extends to other research areas, such as atom, ion, and electron beams. We are sincerely grateful to the anonymous referee, whose comments have led to a sig- nificant improvement of our paper. This research was supported by the National Natural Science Foundation of China (Grants Nos. 10804029, 10904036, 60890202, and 10974049). Acknowledgments V. CONCLUSIONS [1] A. V. Dooghin, N. D. Kundikova, V. S. Liberman, and B. Y. Zeldovich, Phys. Rev. A 45 , 8204 (1992). [2] V. S. Liberman and B. Y. Zeldovich, Phys. Rev. A 46 , 5199 (1992). 17