Analysis of correlations between dipole transitions $1^-_1\rightarrow 0^+_1$ and $3^-_1\rightarrow 2^+_1$ based on the collective model

TL;DR

This paper investigates how the coupling between dipole, quadrupole, and octupole modes affects specific electromagnetic transition ratios in nuclei, using a phenomenological collective model to estimate the impact of giant dipole resonance admixture.

Contribution

It introduces a detailed analysis of mode coupling effects on transition ratios, highlighting the influence of giant dipole resonance admixture within a collective model framework.

Findings

Coupling decreases the $B(E1)$ ratio from the pure model prediction.

Giant dipole resonance admixture significantly affects low-lying mode transition ratios.

The ratio is reduced below the 7/3 value due to mode coupling.

Abstract

The purpose of the work is to evaluate effect of the isovector dipole and quadrupole-octupole modes coupling on the $B(E1;1^-_1\rightarrow 0^+_1)/B(E1;3^-_1\rightarrow 2^+_1)$ ratio. The Hamiltonian of the phenomenological collective model is used to calculate mixing of the isovector dipole and quadrupole and octupole modes. The effect of the admixture of the giant dipole resonance to the low-lying collective quadrupole and octupole modes is estimated. It is shown that the coupling of the quadrupole and octupole collective modes to giant dipole resonance leads to decrease of the ratio $B(E1;1^-_1\rightarrow 0^+_1)/B(E1;3^-_1\rightarrow 2^+_1)$ relative to the value 7/3 predicted by the pure collective quadrupole-octupole model.