Possible existence of pygmy dipole resonance built on excited states in a neutron-rich $^{80}$Ge nucleus
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| Format: | Preprint |
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2025
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| _version_ | 1866917980609183744 |
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| author | Phuc, L. Tan Dang, N. Dinh Li, R. Hung, N. Quang |
| author_facet | Phuc, L. Tan Dang, N. Dinh Li, R. Hung, N. Quang |
| contents | The pygmy dipole resonance (PDR) at the low-lying tail of the giant dipole resonance (GDR) is an interesting research subject as it carries important information about the nuclear surface with mixed isoscalar and isovector vibrations in $N > Z$ systems. The present paper investigates the possible existence of the PDR built on excited states in a neutron-rich $^{80}$Ge nucleus using the phonon damping model (PDM) with and without pairing correlation at zero and finite temperatures. The results obtained within the PDM with exact pairing (EP+PDM) reveal the appearance of two enhanced $γ$-transitions $E_γ= 7.25$ and 7.35 MeV at $T=0.6$ MeV, which carry the PDR nature and hence implying the possible existence of PDR built on excited states in this nucleus. These two $γ$-energies nicely match with a recent experimental observation, thus indicating the crucial role of the inclusion of exact pairing solution in the precise description of low-lying $γ$-transitions. The partition function-based analysis shows that this predicted PDR at $T=$ 0.6MeV is mainly contributed by the first $2^+$ excited state of the $^{80}$Ge nucleus. The isospin mixing at the nuclear surface is also observed in the investigated PDR at $T=0.6-0.7$ MeV. The primary mechanism underlying the emergence of the hot PDR is found due to the coupling of GDR phonon to non-collective particle-particle and hole-hole configurations at finite temperatures within the PDM framework, along with the shift in particle-hole excitation energies due to thermal pairing correlations |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2504_05797 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Possible existence of pygmy dipole resonance built on excited states in a neutron-rich $^{80}$Ge nucleus Phuc, L. Tan Dang, N. Dinh Li, R. Hung, N. Quang Nuclear Theory The pygmy dipole resonance (PDR) at the low-lying tail of the giant dipole resonance (GDR) is an interesting research subject as it carries important information about the nuclear surface with mixed isoscalar and isovector vibrations in $N > Z$ systems. The present paper investigates the possible existence of the PDR built on excited states in a neutron-rich $^{80}$Ge nucleus using the phonon damping model (PDM) with and without pairing correlation at zero and finite temperatures. The results obtained within the PDM with exact pairing (EP+PDM) reveal the appearance of two enhanced $γ$-transitions $E_γ= 7.25$ and 7.35 MeV at $T=0.6$ MeV, which carry the PDR nature and hence implying the possible existence of PDR built on excited states in this nucleus. These two $γ$-energies nicely match with a recent experimental observation, thus indicating the crucial role of the inclusion of exact pairing solution in the precise description of low-lying $γ$-transitions. The partition function-based analysis shows that this predicted PDR at $T=$ 0.6MeV is mainly contributed by the first $2^+$ excited state of the $^{80}$Ge nucleus. The isospin mixing at the nuclear surface is also observed in the investigated PDR at $T=0.6-0.7$ MeV. The primary mechanism underlying the emergence of the hot PDR is found due to the coupling of GDR phonon to non-collective particle-particle and hole-hole configurations at finite temperatures within the PDM framework, along with the shift in particle-hole excitation energies due to thermal pairing correlations |
| title | Possible existence of pygmy dipole resonance built on excited states in a neutron-rich $^{80}$Ge nucleus |
| topic | Nuclear Theory |
| url | https://arxiv.org/abs/2504.05797 |