Title: Neutron-proton pairing correction in the extended isovector and isoscalar pairing model

Abstract

An extended O_ST(8) model with multi j-orbits is constructed based on the angular momentum decomposition with “pseudo”-spin S for valence nucleons in a j-orbit. It is shown that the isovector S = 0 and T=1 pairs are exactly the J=0 and T=1 pairs in a given j-orbit, while the isoscalar S = 1 pairs are linear combinations of J=odd pairs, with which the pairing Hamiltonian can be used to estimate isovector and isoscalar pairing interactions. As an example of the model application, some low-lying J = 0⁺ level energies of even-even and odd-odd A=18 – 28 nuclei up to the half-filling in the ds-shell above the ¹⁶O core are fit by the model and compared with the fitting results of the same Hamiltonian in the O_LST(8) form. It has been verified from the fitting of both the models that the isoscalar pairing interaction can be neglected in the lower energy part of the spectra of these ds-shell nuclei as far as binding energies and a few J=0⁺ excited levels of these nuclei are concerned. With the mean-field plus isovector pairing interaction only, neutron-neutron, proton-proton, and neutron-proton pairing contributions at the ground or the lowest J=0⁺ state of these nuclei aremore » estimated. It is shown that the isovector np-pairing contribution to the binding in the odd-odd N=Z nuclei is systematically larger than that in the even-even nuclei. Furthermore, the isoscalar np-pair content at the lowest J=0+ state of these nuclei is also estimated. In both the O_ST(8) and O_LST(8) models, it is clearly shown that the isoscalar-pair content in the lowest J=0⁺ state of the N=Z and N=Z±2 nuclei increases with increasing of the valence nucleons, especially in those even-even nuclei, which indicates the isoscalar pairing correlation to be of importance at low-lying states of N=Z and N=Z±2 nuclei, especially in those even-even nuclei with more valence nucleons up to the half-filling, even though the isoscalar pairing interaction is negligible.« less

Authors:

Pan, Feng  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-5118-1719"

He, Yingwen ^[2]; Wu, Yingxin ^[2]; Wang, Yu ^[2]; Launey, Kristina D. ^[3]; Draayer, Jerry P.  ^[3]

• Search DOE PAGES for author "Draayer, Jerry P."
• Search DOE PAGES for ORCID "0000-0003-3568-8223"

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+ Show Author Affiliations

1. Liaoning Normal University, Dalian (China); Louisiana State Univ., Baton Rouge, LA (United States)
2. Liaoning Normal University, Dalian (China)
3. Louisiana State Univ., Baton Rouge, LA (United States)

Publication Date:

Wed Oct 07 00:00:00 EDT 2020

Research Org.:

Louisiana State Univ., Baton Rouge, LA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1850906

Grant/Contract Number:  

SC0005248

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review. C

Additional Journal Information:

Journal Volume: 102; Journal Issue: 4; Journal ID: ISSN 2469-9985

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Physics; Binding energy & masses; Models based on symmetries; Nuclear forces; Nuclear many-body theory; 20 ≤ A ≤ 38; 6 ≤ A ≤ 19