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

Pan, Feng; He, Yingwen; Wu, Yingxin; Wang, Yu; Launey, Kristina D.; Draayer, Jerry P.

doi:10.1103/physrevc.102.044306

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

Journal Article · Wed Oct 07 00:00:00 EDT 2020 · Physical Review. C

DOI:https://doi.org/10.1103/physrevc.102.044306· OSTI ID:1850906

^[1]; He, Yingwen ^[2]; Wu, Yingxin ^[2]; Wang, Yu ^[2]; Launey, Kristina D. ^[3];

^[3]

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

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 are 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.

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

Sponsoring Organization:: USDOE Office of Science (SC)

Grant/Contract Number:: SC0005248

OSTI ID:: 1850906

Journal Information:: Physical Review. C, Vol. 102, Issue 4; ISSN 2469-9985

Publisher:: American Physical Society (APS)Copyright Statement

Country of Publication:: United States

Language:: English

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