Effects of phonon-phonon coupling on properties of pygmy resonance in $^{124-132}$Sn

TL;DR

This paper investigates how phonon-phonon coupling influences the low-energy electric dipole response in tin isotopes, using QRPA calculations with an effective Skyrme interaction, and finds that two-phonon configurations significantly affect the pygmy resonance.

Contribution

It introduces a detailed analysis of phonon-phonon coupling effects on pygmy resonances in tin isotopes using a finite rank separable QRPA approach with Skyrme interactions.

Findings

Two-phonon configurations significantly contribute to low-lying strength.

The calculated $E1$ strength distribution agrees reasonably with experimental data.

Phonon-phonon coupling affects the properties of pygmy resonances.

Abstract

Starting from an effective Skyrme interaction we study effects of phonon-phonon coupling on the low-energy electric dipole response in $^{124-132}$Sn. The QRPA calculations are performed within a finite rank separable approximation. The inclusion of two-phonon configurations gives a considerable contribution to low-lying strength. Comparison with available experimental data shows a reasonable agreement for the low-energy $E1$ strength distribution.