Spreading widths of giant monopole resonance in the lead region: Random matrix approach

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Hauptverfasser: Arsenyev, N. N., Severyukhin, A. P., Nazmitdinov, R. G.
Format: Preprint
Veröffentlicht: 2023
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author Arsenyev, N. N.
Severyukhin, A. P.
Nazmitdinov, R. G.
author_facet Arsenyev, N. N.
Severyukhin, A. P.
Nazmitdinov, R. G.
contents The microscopic calculation of the decay width of giant monopole resonance (GMR) anticipates the mixing of one-phonon states with configurations of increasing complexity. To this aim we develop the effective approach for description of monopole excited states that are obtained in the quasiparticle random phase approximation (QRPA), with regard of the coupling between one- and two-phonon states. Based on the QRPA one-phonon states, we generate the coupling and two-phonon states by means of the Gaussian orthogonal ensemble (GOE) distribution. Within our approach the spreading width of the GMRs in $^{204,206,208}$Pb are described by means of a random matrix approach on two energy scales. It is demonstrated that the main contribution into the decay of the GMR is determined by a small number of two-phonon states strongly coupled to low-energy surface vibrations. While a vast majority of the coupling matrix elements (that are small in value and following the GOE distribution) are responsible for the fine structure of the GMR spreading width. A remarkable agreement between the results of the full microscopic calculations (based on QRPA phonons coupled by means of the microscopic coupling matrix elements with calculated two-phonon states) with those of the developed approach confirms the vitality of the proposed ideas.
format Preprint
id arxiv_https___arxiv_org_abs_2311_05397
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Spreading widths of giant monopole resonance in the lead region: Random matrix approach
Arsenyev, N. N.
Severyukhin, A. P.
Nazmitdinov, R. G.
Nuclear Theory
Nuclear Experiment
The microscopic calculation of the decay width of giant monopole resonance (GMR) anticipates the mixing of one-phonon states with configurations of increasing complexity. To this aim we develop the effective approach for description of monopole excited states that are obtained in the quasiparticle random phase approximation (QRPA), with regard of the coupling between one- and two-phonon states. Based on the QRPA one-phonon states, we generate the coupling and two-phonon states by means of the Gaussian orthogonal ensemble (GOE) distribution. Within our approach the spreading width of the GMRs in $^{204,206,208}$Pb are described by means of a random matrix approach on two energy scales. It is demonstrated that the main contribution into the decay of the GMR is determined by a small number of two-phonon states strongly coupled to low-energy surface vibrations. While a vast majority of the coupling matrix elements (that are small in value and following the GOE distribution) are responsible for the fine structure of the GMR spreading width. A remarkable agreement between the results of the full microscopic calculations (based on QRPA phonons coupled by means of the microscopic coupling matrix elements with calculated two-phonon states) with those of the developed approach confirms the vitality of the proposed ideas.
title Spreading widths of giant monopole resonance in the lead region: Random matrix approach
topic Nuclear Theory
Nuclear Experiment
url https://arxiv.org/abs/2311.05397