Exact solution of mean-field plus an extended T = 1 nuclear pairing Hamiltonian in the seniority-zero symmetric subspace

Pan, Feng; Ding, Xiaoxue; Launey, Kristina D.; Dai, L. R.; Draayer, J. P.

doi:10.1016/j.physletb.2018.02.054

Cited by 3 publications

(1 citation statement)

References 35 publications

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“…Other O(5) seniority-nonzero states constructed by (J = even, T = 1) and (J = odd, T = 0) pair operators coupled to J = 0 and at least with the total O(5) seniority number v = 4 are not considered as an approximation, of which J π = 0 + isovector pairing matrix elements are comparatively small, so that these seniority-nonzero states have less contribution to the low-lying J π = 0 + states as long as the isoscalar pairing interaction is negligible. As shown in our previous works [21,[25][26][27], such an approximation seems adequate as far as binding energies and a few low-lying J π = 0 + level energies are concerned.…”

Section: Labelling Scheme Withmentioning

confidence: 75%

On the importance of np-pairs in the isovector pairing model

Pan

Dai

et al. 2020

EPL

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It is shown that the isovector np-pair number operator can be realized in the O(5) quasi-spin basis. The computation of the isovector np-pair number is demonstrated for even-even and odd-odd ds-shell nuclei described by the charge-independent mean field plus isovector pairing model restricted within the O(5) seniority-zero subspace, thereby binding energies and low-lying excited states of these ds-shell nuclei are fit, along with estimates for the isovector neutron-proton pairing contributions. For reasonable neutron-proton pairing strengths the isovector np-pairing energy contribution to the total binding energy in odd-odd N = Z nuclei is systematically larger than that in the even-even nuclei. In sum, the results suggest that the isovector np-pairing mode is favored in odd-odd N = Z nuclei; and additionally, a decrease in the double binding-energy difference for odd-odd nuclei is primarily due to the symmetry and Wigner energy contributions to the binding energy.

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Section: Labelling Scheme Withmentioning

confidence: 75%

On the importance of np-pairs in the isovector pairing model

Pan

Dai

et al. 2020

EPL

Self Cite

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Exact isovector pairing in a shell-model framework: Role of proton-neutron correlations in isobaric analog states

et al. 2019

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We utilize a nuclear shell model Hamiltonian with only two adjustable parameters to generate, for the first time, exact solutions for pairing correlations for light to medium-mass nuclei, including the challenging proton-neutron pairs, while also identifying the primary physics involved. In addition to single-particle energy and Coulomb potential terms, the shell model Hamiltonian consists of an isovector T = 1 pairing interaction and an average proton-neutron isoscalar T = 0 interaction, where the T = 0 term describes the average interaction between non-paired protons and neutrons. This Hamiltonian is exactly solvable, where, utilizing 3 to 7 single-particle energy levels, we reproduce experimental data for 0 + state energies for isotopes with mass A = 10 through A = 62 exceptionally well including isotopes from He to Ge. Additionally, we isolate effects due to like-particle and protonneutron pairing, provide estimates for the total and proton-neutron pairing gaps, and reproduce N (neutron) = Z (proton) irregularity. These results provide a further understanding for the key role of proton-neutron pairing correlations in nuclei, which is especially important for waiting-point nuclei on the rp-path of nucleosynthesis.

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Isovector plus isoscalar neutron–proton pairing effect on nuclear statistical quantities using a path integral approach

Mokhtari

Allal

Fellah

2018

Int. J. Mod. Phys. E

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Gap equations at finite temperature are established in the isovector plus isoscalar pairing case [Formula: see text] using a path integral approach. Expressions of the various statistical quantities, i.e., the energy, the entropy and the heat capacity are then deduced. It is shown that they do generalize the ones obtained in the pure isovector ([Formula: see text]) pairing case, as well as those obtained within the conventional finite temperature Bardeen–Cooper–Schrieffer (FTBCS) theory in the pairing between like-particles case. A numerical study is then performed using the schematic one-level model. It is shown that the isoscalar n–p gap parameter [Formula: see text] behaves as a function of the temperature, like its homologues [Formula: see text] and [Formula: see text] in the conventional FTBCS approach. As for the three other gap parameters, i.e., [Formula: see text], [Formula: see text] and [Formula: see text], their behaviors are clearly modified when the isoscalar pairing is taken into account. In particular, one observes a shift of the values of the critical temperatures. Dealing with the statistical quantities, the inclusion of the isoscalar pairing, in addition to the isovector one, leads to a lowering of the energy as well as a change of the shapes of the curves of the energy, the entropy and the heat capacity as a function of the temperature.

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Exact solution of mean-field plus an extended T = 1 nuclear pairing Hamiltonian in the seniority-zero symmetric subspace

Cited by 3 publications

References 35 publications

On the importance of np-pairs in the isovector pairing model

On the importance of np-pairs in the isovector pairing model

Exact isovector pairing in a shell-model framework: Role of proton-neutron correlations in isobaric analog states

Isovector plus isoscalar neutron–proton pairing effect on nuclear statistical quantities using a path integral approach

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