Occurrence of high-lying rotational bands in the interacting boson model

Abstract

We observe an adiabatic separation of collective rotations built upon a subset of intrinsic vibrational states within the interacting boson model (IBM) in the parameter domains corresponding to axially deformed ground state. The effect is not limited only to the low-lying states and closely follows the variation of quantum and classical measures of regularity. It leads to the existence of rotational bands even close to the highest accessible energies in specific regions within the IBM symmetry triangle. We propose a more general effect of regular intrinsic dynamics on the adiabatic separation of intrinsic and collective motion.

Simultaneous occurrence of distinct symmetries in nuclei

“…The non-solvable K-bands are mixed with respect to SU(3) in a coherent, L-independent manner, hence exemplify SU(3)-QDS. As expected, the Pearson correlator [26] is C SU3 (0 i −6) ≈ 1, for these regular K-bands. The above results demonstrate that PDS and QDS can characterize the remaining regularity in a system, amidst a complicated (at time chaotic) environment of other states.…”

Jacobi-type transitions in the interacting boson model

“…As seen from Fig. 2(a), the constant-energy surfaces develop a clear low-energy well (blue color) around β ≃ √ 2 and γ = 0 • , which indicates that the states confined in the well are γ-rigid [28,29] and associated with the SU(3) quasidynamical symmetry [28,30,31]. Once they are excited out of the low-energy well (as signified with the arrow in Fig.…”

“…In general, the γ-rigid to γ-soft transition is present in all the deformed region of the phase diagram but with different properties. The γ-soft characteristics may come either from the U(5) or SO(6) DS or their mixing while the γ-rigid characteristics originate from the SU(3) DS [28,29].…”

Analytic derivation of an approximate SU(3) symmetry inside the symmetry triangle of the interacting boson approximation model

“…[9] was limited to the low-lying part of the spectrum, while regularity amidst chaoticity has been discovered by Alhassid and Whelan through the study of the whole spectrum [2,3]. The properties of high-lying rotational bands built on axially deformed ground states have been studied recently [17] in the IBA, showing signatures of a SU(3) QDS extending to the highest part of the IBA spectrum.…”