Partial Dynamical Symmetries in the Nuclear Many-Body System

Rajiv Gupta

Jutta Escher

A. Leviatan

We introduce the notions of partial dynamical symmetry (PDS) and quasi dynamical symmetry (QDS) and demonstrate their relevance to nuclear spectroscopy, to quantum phase transitions and to mixed systems with regularity and chaos. The analysis serves to highlight the potential role of PDS and QDS towards understanding the emergent "simplicity out of complexity" exhibited by complex many-body systems.

P. Van Isacker

Jutta Escher

Partial dynamical symmetry (PDS) extends and complements the concepts of exact and dynamical symmetry. It allows one to remove undesired constraints from an algebraic theory, while preserving some of the useful aspects of a dynamical symmetry, and to study the effects of symmetry breaking in a controlled manner. An example of a PDS in an interacting fermion system is presented. The associated PDS Hamiltonians are closely related with a realistic quadrupole-quadrupole interaction and provide new insights into this important interaction.

Wei-Min Zhang, D.H. Feng

In this paper, the dynamical symmetry concept is used to investigate the quantum integrability of nuclear many-body systems. It is found that such systems are generally nonintegrable due to the complicated inherent interactions. In fact, in certain regions of the intrinsic parameters, the time-dependent mean-field solution can be chaotic. However, when subdynamical symmetries, e.g., certain excitation modes, dominate, the corresponding dynamics will be rendered regular, thus signaling that the nuclear many-body system is not fully chaotic. Chaotic behavior emerges in the transitional region between the excitation modes where subdynamical symmetries are broken and accompanied by structural phase transitions.