Role of tensor forces in nuclei

Abstract

Recently, calculations of the ground states of the lightest nuclei have been performed using highly accurate data on realistic internucleon forces. In this paper, these results were used to describe the properties of nuclei with nucleon numbers $A>4$. Taking into account tensor forces leads to the conclusion that the four subsystems in the nucleus with zero nucleon orbital momenta are combined predominantly into the $^1S_0$ cluster. Subsystems with nonzero orbital momenta also combine into clusters with lower potential energy. This approach allows us to consistently explain the lifetime of the $^8$Be nucleus, the Hoyle state, the sequential mechanism of the reaction with the emission of $α$ particles, the shift of the reaction threshold, and more. The assumption of the existence of a one-dimensional effective interaction of nucleons in the nucleus leads to the conclusion that the nucleus contains a "power center" and, accordingly, nucleons have orbital angular momenta relative to this "power center." Our approach does not predict the presence of such a "power center" in the nucleus.