Fragmentation of electric dipole strength in N=82 isotones

TL;DR

This paper investigates how the electric dipole strength in N=82 isotones is fragmented due to complex nuclear interactions, using advanced theoretical models to better match experimental observations.

Contribution

It applies the second random-phase approximation (SRPA) to analyze dipole strength fragmentation, revealing the impact of 2p2h couplings on low-energy states, which is a novel approach.

Findings

SRPA provides additional damping of the giant dipole resonance.

Low-energy dipole strength is redistributed due to 2p2h coupling.

Results agree reasonably with experimental data.

Abstract

Fragmentation of the dipole strength in the N=82 isotones 140Ce, 142Nd and 144Sm is calculated using the second random-phase approximation (SRPA). In comparison with the result of the random-phase approximation (RPA), the SRPA provides the additional damping of the giant dipole resonance and the redistribution of the low-energy dipole strength. Properties of the low-energy dipole states are significantly changed by the coupling to two-particle-two-hole (2p2h) states, which are also sensitive to the correlation among the 2p2h states. Comparison with available experimental data shows a reasonable agreement for the low-energy E1 strength distribution.