Optimal pair density functional for the description of nuclei with large neutron excess

Yamagami, M.; Shimizu, Yoshifumi R.; Nakatsukasa, Takashi

doi:10.1103/physrevc.80.064301

Cited by 54 publications

(85 citation statements)

References 60 publications

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“…We should note, however, that a densitydependent pairing functional needs to be investigated. Recent work [59] has shown that isovector-density dependence [60] allows a good reproduction of the dependence of pairing gaps on isotope. Such a functional might affect the isotopic dependence of E2 strength as well.…”

Section: B N -And Z-dependencementioning

confidence: 99%

Testing Skyrme energy-density functionals with the quasiparticle random-phase approximation in low-lying vibrational states of rare-earth nuclei

Terasaki

Engel

2011

Phys. Rev. C

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Although nuclear energy density functionals are determined primarily by fitting to ground state properties, they are often applied in nuclear astrophysics to excited states, usually through the quasiparticle random phase approximation (QRPA). Here we test the Skyrme functionals SkM * and SLy4 along with the self-consistent QRPA by calculating properties of low-lying vibrational states in a large number of well-deformed even-even rare-earth nuclei. We reproduce trends in energies and transition probabilities associated with γ-vibrational states, but our results are not perfect and indicate the presences of multi-particle-hole correlations that are not included in the QRPA. The Skyrme functional SkM * performs noticeably better than SLy4. In a few nuclei, changes in the treatment of the pairing energy functional have a significant effect. The QRPA is less successful with "β-vibrational" states than with the γ-vibrational states.

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Section: B N -And Z-dependencementioning

confidence: 99%

Testing Skyrme energy-density functionals with the quasiparticle random-phase approximation in low-lying vibrational states of rare-earth nuclei

Terasaki

Engel

2011

Phys. Rev. C

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“…The starting point of the model is the energy density functional, which we construct from the Skyrme interaction with the parameter set SLy4 [31], and the densitydependent delta interaction (DDDI) adopted as an effective pairing force [13,16,20,[32][33][34][35][36][37][38][39][40][41]. The DDDI is given by…”

Section: Skyrme-hartree-fock-bogoliubov Mean-field Plus Qrpa Apprmentioning

confidence: 99%

Anomalous pairing vibration in neutron-rich Sn isotopes beyond theN=82magic number

Shimoyama

2011

Phys. Rev. C

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Two-neutron transfer associated with the pair correlation in superfluid neutron-rich nuclei is studied with focus on low-lying 0 + states in Sn isotopes beyond the N = 82 magic number. We describe microscopically the two-neutron addition and removal transitions by means of the Skyrme-HartreeFock-Bogoliubov mean-field model and the continuum quasiparticle random phase approximation formulated in the coordinate space representation. It is found that the pair transfer strength for the transitions between the ground states becomes significantly large for the isotopes with A ≥ 140, reflecting very small neutron separation energy and long tails of the weakly bound 3p orbits. In 132−140 Sn, a peculiar feature of the pair transfer is seen in transitions to low-lying excited 0 + states. They can be regarded as a novel kind of pair vibrational mode which is characterized by an anomalously long tail of the transition density extending to far outside of the nuclear surface, and a large strength comparable to that of the ground-state transitions. The presence of the weakly bound neutron orbits plays a central role for these anomalous behaviors.

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“…Our calculations reproduce well the neutron number dependence of experimental data for binding energy, two-neutron separation energy, and odd-even mass staggering of these isotopes with the interaction IS+IV Bare. Recently, the isospin dependent interaction is extended to introduce the quadratic terms of isospin and applied to a wide region of nuclei in the mass table [9]. These results suggest that by introducing the isovector term in the pairing interaction, one can construct a global effective pairing interaction which is applicable to nuclei in a wide range of the nuclear chart.…”

Section: Discussionmentioning

confidence: 99%

New type of Pairing interactions in nuclear matter and finite nuclei

Sagawa¹,

Margueron²,

Hagino³

2011

J. Phys.: Conf. Ser.

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Abstract. We propose new types of density dependent contact pairing interaction which reproduce pairing gaps in a wide range of nuclear mass table.We discuss also the relation between the proposed paring interactions and the pairing gaps in symmetric and neutron matters obtained by a microscopic treatment based on a bare nucleonnucleon interaction. It is shown that the isovector type pairing interaction is necessary on top of the isoscalar term to reproduce systematically nuclear empirical pairing gaps. The BCS-BEC crossover of neutrons pairs in symmetric and asymmetric nuclear matters is studied by using these contact interactions. It is shown that the bare and screened pairing interactions lead to different features of the BCS-BEC crossover in symmetric nuclear matter. IntroductionIt has been known that the pairing correlations play an important role in finite and also infinite nuclear systems. There are mainly two different approaches for a calculation of pairing correlations in finite nuclei. The first approach is based on phenomenological pairing interactions whose parameters are determined using some selected data [1], while the second approach starts from a bare nucleon-nucleon interaction and eventually includes the effect of phonon coupling [2]. The latter approach has shown that the medium polarization reduces the pairing gaps in neutron matter while the neutron pairing gaps in symmetric matter are much enlarged at low density compared to that of the bare calculation. This enhancement takes place especially for neutron Fermi momenta k Fn < 0.7 fm −1 .In this report, we propose effective density-dependent pairing interactions which reproduce both the neutron-neutron (nn) scattering length at zero density and the neutron pairing gap in uniform matter. In order to simultaneously describe the density dependence of the neutron pairing gap for both symmetric and neutron matter, it is necessary to include an isospin dependence in the effective pairing interaction. Depending on whether the medium polarization effects on the pairing gap given in Ref.[3] are taken into account or not, we invent two different density dependences in the pairing interaction. Then, we apply these interactions to study BCS-BEC cross-over in infinite systems and also pairing gaps in semi-magic finite nuclei, such as Ca, Ni, Sn and Pb isotopic chains.

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Optimal pair density functional for the description of nuclei with large neutron excess

Cited by 54 publications

References 60 publications

Testing Skyrme energy-density functionals with the quasiparticle random-phase approximation in low-lying vibrational states of rare-earth nuclei

Testing Skyrme energy-density functionals with the quasiparticle random-phase approximation in low-lying vibrational states of rare-earth nuclei

Anomalous pairing vibration in neutron-rich Sn isotopes beyond theN=82magic number

New type of Pairing interactions in nuclear matter and finite nuclei

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