Training Manual . M. Moscow Post . Un-ta, 1985. — 96 s. A statement of the non-relativistic theory S - matrix. Initially, S - matrix is obtained in the form of a series of perturbations on the interaction potential. Then, by summing the series, the Lippmann-Schwinger equation . is obtained. An exact relationship is also obtained between the scattering amplitude and the potential. Dispersion of non-relativistic particles with spin . Specified apparatus of spin matrix density. The restrictions that impose on the invariance principles regarding rotations, reflections and reversals of time. are discussed in detail. On the basis of the principles of invariance, an important theorem on the equality of polarization and asymmetry . is obtained and analyzed in detail. For students of the Faculty of Physics of Moscow State University, theorists and experimenters . Reviewers:Academician B. M. Pontecorvokand . phys. -mat. Science C. P. Ivanova