Boson Model Of Nuclei Research Articles

Regularity and chaos at critical points of first-order quantum phase transitions

We study the interplay between regular and chaotic dynamics at the critical point of a generic first-order quantum phase transition in an interacting boson model of nuclei. A classical analysis reveals a distinct behavior of the coexisting phases in a broad energy range. The dynamics is completely regular in the deformed phase and, simultaneously, strongly chaotic in the spherical phase. A quantum analysis of the spectra separates the regular states from the irregular ones, assigns them to particular phases, and discloses persisting regular rotational bands in the deformed region.

Nonperipheral effects in medium energy proton scattering on collective nuclear states.

The Glauber approximation is combined with the interacting boson model of nuclei to describe medium energy proton scattering to collective states. Channel coupling effects are included to all orders. Nonperipheral contributions are found to be nonnegligible, especially for small angles. As an illustration, cross sections for the excitation of the low lying ${J}^{\ensuremath{\pi}}$${=0}^{+}$, ${2}^{+}$ states in $^{154}\mathrm{Gd}$ are presented.

The Composite Particle Representation Theory: (I) The Composite Particle Representation Transformation

A generalization of the quantum mechanical representation transformation is presented, in this paper. It is shown that, as an important example, the Boson-expansion method, commonly employed in nuclear physics, corresponds to such a generalized transformation. Using this generalization, we were able to construct a special representation called the “Composite Particle Representation”. In the composite, particle representation, the composite particle degrees of freedom are included, as well as the original particle degrees of freedom. The former is introduced in order that the motion of certain particle clusters can be described as separate entities in a many-body system. This representation is shown to be exactly equivalent to the usual quantum mechanical representation which includes only the original particle degrees of freedom. Many applications of this theory are expected, in particular in the study of hadrons from the quark point of view and the Interacting Boson Model in nuclei.

Generalization of the U(6) boson model

An attempt has been made to generalize the U(6) boson model for nuclei introduced by Arima and Iachello by allowing the bosons to populate, in addition to the $L=0 \mathrm{and} 2$, the $L=4,6,\dots{},{L}_{max}$ excited levels. In this expanded space, a generalized boson degeneracy $g$ is defined. It is then shown that in the generalized space the interacting boson model will have the same simple features by explicitly looking at the rotational limit.NUCLEAR STRUCTURE U(6) interacting boson approximation generalized. Odd-$K$ bands, band cutoffs predicted.