Application and development of Lobachevskiĭ ideas in modern physics (Russian).
Obʺed. Inst. Yadernykh Issled., Dubna.
2004.
P. 160-170
Summary (translated from the Russian): "In the framework of general relativity for the {rm SU}(2) sigma model, we construct an exact cylindrically symmetric (vortex) solution of the equations of motion, which is characterized by the topological charge of the type that is a power of a mapping and by the angular deficit. We prove the linearized stability of the vortices in the sense of Lyapunov and compute the angle of deviation of a light beam in the gravitational field of a vortex (the gravitational lens effect)."