I. INTRODUCTION The optical Magnus effect is the photonic version of the Magnus effect in classical me- chanical systems. As a result of the usual mechanical Magnus effect, a rotating ball falling through the air is deflected from the vertical to the direction of rotation. The influence of spin on the trajectory can be considered as the optical analogue of the mechanical Magnus effect. The spin photon to some extent can be regarded as a rotating ball, and then after multiple reflections during its propagation through a fiber the photon will be deflected from its initial trajectory [1, 2]. Hence this effect has received the name of optical Magnus effect or optical ping-pong effect. Recently, the physical nature of the optical Magnus effect is connected with spin-orbital interaction in a wave field, which essentially depends on the gradient of a refractive index of optical medium [3]. For beams propagating in the free space, it is generally believed that the optical magnus effect takes no place since the gradient of a refractive index is zero. In fact, the changes in transverse momentum currents can lead to the rotation phenomenon in paraxial light beams. The possible occurrence of a polarization-dependent rotation of beam centroid in the free space was already predicted by Borodavka and coworkers [4]. However, they do not connect such a rotation with the occurrence of nonzero transverse momentum currents. In our opinion, the optical Magnus effect manifests itself within vector field structure in the frame of classical electrodynamics. However, the Jones vector is not sufficient to describe the vectorial property of a finite beam, due to the longitudinal component [5]. Thus, it is necessary for us to establish a general vector field model to reveal the role of transverse momentum currents in optical Magnus effect. Meanwhile the same interaction also leads to other effects such as the spin Hall effect of light (SHEL) [6, 7]. The interesting effect has been recently observed in beam refrac- tion [8] and in scattering from dielectric spheres [9]. More recently, the SHEL was found to occur when a light beam is observed on the direction making an angle with the propagation axis [10]. This effect has a purely geometric nature and amounts to a polarization-dependent shift or split of the beam intensity distribution. As the tilting angle tends to zero, the split- ting effect vanishes. The possible reason for this is that the transverse intensity distribution of fundamental Gaussian beam is axially symmetric and the polarization-dependent rotation, if it exists, cannot be observed directly. We believe that such a polarization-dependent shift should be unavoidable when the beam possesses the transverse momentum currents. Thus, 2