https://doi.org/10.1140/epja/s10050-020-00084-1
Regular Article - Theoretical Physics
Exact solution of spherical mean-field plus multi-pair interaction model with two non-degenerate j-orbits
1
Department of Physics, Liaoning Normal University, Dalian, 116029, China
2
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA, 70803-4001, USA
* e-mail: daipan@dlut.edu.cn
Received:
26
November
2019
Accepted:
4
February
2020
Published online:
4
March
2020
The exact solution of spherical mean-field plus multi-pair interaction model with two non-degenerate j-orbits, which is an extension of the widely used standard (two-body) pairing model, is derived based on the Bethe–Richardson–Gaudin approach. The Bethe–Richardson–Gaudin equations in determining eigenstates and the corresponding eigen-energies of the model are provided and exemplified with up to three-pair interactions. With a suitable parameterization of the overall multi-pair interaction strengths, the model with one adjustable parameter and valence nucleons confined in the 
and 
orbits is applied to fit binding energies of 
Sn. It is shown that the ground-state occupation probabilities of nucleon pairs calculated from this model and those from the standard pairing model are almost the same with perfect ground-state overlap of the two models. A noticeable feature of the multi-pair interactions is that the even–odd staggering of pairing interaction strength appearing in the standard pairing model due to the Pauli-blocking is suppressed. As the result, the pairing interaction strength of the model only depends on the number of valence nucleon pairs in the system.
© Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature, 2020
