Ab initio nuclear shape coexistence and emergence of island of inversion around N = 20

We extend a nuclear ab initio framework based on chiral two- and three-nucleon interactions to investigate shape coexistence and the degradation of the N=20 magic number in both even-even and odd-even magnesium isotopes. The quantum-number projected generator coordinate method, combined with the in-...

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Main Authors: E.F. Zhou, C.R. Ding, J.M. Yao, B. Bally, H. Hergert, C.F. Jiao, T.R. Rodríguez
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:Physics Letters B
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Online Access:http://www.sciencedirect.com/science/article/pii/S0370269325002254
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author E.F. Zhou
C.R. Ding
J.M. Yao
B. Bally
H. Hergert
C.F. Jiao
T.R. Rodríguez
author_facet E.F. Zhou
C.R. Ding
J.M. Yao
B. Bally
H. Hergert
C.F. Jiao
T.R. Rodríguez
author_sort E.F. Zhou
collection DOAJ
description We extend a nuclear ab initio framework based on chiral two- and three-nucleon interactions to investigate shape coexistence and the degradation of the N=20 magic number in both even-even and odd-even magnesium isotopes. The quantum-number projected generator coordinate method, combined with the in-medium similarity renormalization group (IMSRG), is employed to compute their low-lying states. This approach reasonably reproduces the coexistence of weakly and strongly deformed states at comparable energies, and allows us to track the emergence of the N=20 island of inversion through the continuous IMSRG evolution of the chiral Hamiltonian. Our results indicate that the ground state of 33Mg with spin-parity 3/2− is predominantly a strongly deformed configuration with Kπ=3/2−, while the lowest 7/2− state is predicted to be a shape isomer, consisting of a mixture of weakly deformed configurations with different K values. The results highlight the essential roles of both dynamical and static collective correlations in reproducing the ordering of nuclear states with distinct shapes.
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spelling doaj-art-3ef76e020bcf41b5b7208c975e2170c32025-08-20T02:27:24ZengElsevierPhysics Letters B0370-26932025-06-0186513946410.1016/j.physletb.2025.139464Ab initio nuclear shape coexistence and emergence of island of inversion around N = 20E.F. Zhou0C.R. Ding1J.M. Yao2B. Bally3H. Hergert4C.F. Jiao5T.R. Rodríguez6School of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082, PR China; Guangdong Provincial Key Laboratory of Quantum Metrology and Sensing, Sun Yat-Sen University, Zhuhai 519082, ChinaSchool of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082, PR China; Guangdong Provincial Key Laboratory of Quantum Metrology and Sensing, Sun Yat-Sen University, Zhuhai 519082, ChinaSchool of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082, PR China; Guangdong Provincial Key Laboratory of Quantum Metrology and Sensing, Sun Yat-Sen University, Zhuhai 519082, China; Corresponding author.ESNT, IRFU, CEA, Université Paris-Saclay, 91191 Gif-sur-Yvette, FranceFacility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824-1321, USA; Department of Physics & Astronomy, Michigan State University, East Lansing, MI 48824-1321, USASchool of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082, PR China; Guangdong Provincial Key Laboratory of Quantum Metrology and Sensing, Sun Yat-Sen University, Zhuhai 519082, ChinaDepartamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, E-28040 Madrid, SpainWe extend a nuclear ab initio framework based on chiral two- and three-nucleon interactions to investigate shape coexistence and the degradation of the N=20 magic number in both even-even and odd-even magnesium isotopes. The quantum-number projected generator coordinate method, combined with the in-medium similarity renormalization group (IMSRG), is employed to compute their low-lying states. This approach reasonably reproduces the coexistence of weakly and strongly deformed states at comparable energies, and allows us to track the emergence of the N=20 island of inversion through the continuous IMSRG evolution of the chiral Hamiltonian. Our results indicate that the ground state of 33Mg with spin-parity 3/2− is predominantly a strongly deformed configuration with Kπ=3/2−, while the lowest 7/2− state is predicted to be a shape isomer, consisting of a mixture of weakly deformed configurations with different K values. The results highlight the essential roles of both dynamical and static collective correlations in reproducing the ordering of nuclear states with distinct shapes.http://www.sciencedirect.com/science/article/pii/S0370269325002254Nuclear ab initio methodNuclear chiral HamiltonianN = 20 island of inversion
spellingShingle E.F. Zhou
C.R. Ding
J.M. Yao
B. Bally
H. Hergert
C.F. Jiao
T.R. Rodríguez
Ab initio nuclear shape coexistence and emergence of island of inversion around N = 20
Physics Letters B
Nuclear ab initio method
Nuclear chiral Hamiltonian
N = 20 island of inversion
title Ab initio nuclear shape coexistence and emergence of island of inversion around N = 20
title_full Ab initio nuclear shape coexistence and emergence of island of inversion around N = 20
title_fullStr Ab initio nuclear shape coexistence and emergence of island of inversion around N = 20
title_full_unstemmed Ab initio nuclear shape coexistence and emergence of island of inversion around N = 20
title_short Ab initio nuclear shape coexistence and emergence of island of inversion around N = 20
title_sort ab initio nuclear shape coexistence and emergence of island of inversion around n   20
topic Nuclear ab initio method
Nuclear chiral Hamiltonian
N = 20 island of inversion
url http://www.sciencedirect.com/science/article/pii/S0370269325002254
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