Learning the structure of giant resonances from their $\gamma$-decay

TL;DR

This paper uses a microscopic self-consistent model to analyze the gamma-decay of giant resonances in lead-208, revealing how gamma-decay patterns reflect the structure of these nuclear excitations and depend on isospin.

Contribution

It introduces a model that considers effects beyond linear response to study gamma-decay of giant resonances, providing new insights into their wave functions and isospin sensitivity.

Findings

Gamma-decay is highly sensitive to the isospin of states.

A larger weight of the 3_1^- component in GQR wave function was found.

Gamma-decay can serve as a probe for nuclear structure models.

Abstract

The direct $\gamma$-decays of the giant dipole resonance (GDR) and the giant quadrupole resonance (GQR) of $^{208}$Pb to low-lying states are investigated by means of a microscopic self-consistent model. The model considers effects beyond the linear response approximation. The strong sensitivity of $\gamma$-decay to the isospin of the involved states is proven. By comparing their decay widths, a much larger weight of the $3_{1}^{-}$ component in the GQR wave function of $^{208}$Pb is deduced, with respect to the weight of the $2_{1}^{+}$ component in the GDR wave function. Thus, we have shown that $\gamma$-decay is a unique probe of the resonance wave functions, and a testground for nuclear structure models.