SU(3) Symmetry in Atomic Nuclei by V. K. B. Kota

Author:V. K. B. Kota
Language: eng
Format: epub
ISBN: 9789811536038
Publisher: Springer Singapore

7.3.1 Introduction

Important multipolarity next to the quadrupole degree of freedom, in the low-lying levels of heavy nuclei, is the octupole and obviously here in IBM description, one has to include f (octupole) bosons with besides the s and d bosons. Then, we have the sdfIBM and this appears to be a good model as long as only octupole vibrational states are present. This model was analyzed in some detail and applied in some early works [41, 42]. Here, it is possible to have SU(3) in the form of just as we have discussed in the previous section the limit (it is also possible to consider coupled to more than one f boson). However, there is strong evidence that octupole deformation will also occur in nuclei and in this situation, Iachello and collaborators found that sdfIBM is inadequate. In particular in describing the low-lying bands and enhanced E1 strengths, it is found that the cure is to include not only f bosons but also p () bosons. This led to the development of sdpfIBM [43, 44]. It is important to recognize that enhanced E1 strengths can be described using (i) octupole mode [45]; (ii) -clustering and then there will be enhanced E1 transitions due to the oscillations of the cluster relative to the remaining part of the nucleus [46]; (iii) pigmy dipole resonance [47]. See Fig. 7.4 and Ref. [40]. In the sdpfIBM, the E1 strengths arise from the octupole mode via p bosons. Also, microscopic (shell model) studies showed clearly the need to include p bosons [48]. More likely the p boson arises from the collective low-lying valence shell excitation after removing the center-of-mass motion and then the p-state is collective with respect to the operator similar to the octupole operator [43].

The sdpfIBM admits a large number of dynamical symmetries (group–subgroup chains) [49–51] and here below, we will restrict our detailed discussion to the SU(3) limit of the model.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.