Taking ^120Sn as an example, we discuss the pseudospin symmetry in the single proton resonant states by examining the energies, widths and the wavefunctions. The information of the single proton resonant states in sph...Taking ^120Sn as an example, we discuss the pseudospin symmetry in the single proton resonant states by examining the energies, widths and the wavefunctions. The information of the single proton resonant states in spherical nuclei are extracted from an analytic continuation in the coupling constant method within the framework of the self-consistent relativistic mean field theory under the relativistic boundary condition. We find small energy splitting in a pair of pseudospin partners in the resonant states. The lower components of the Dirac wavefunctions of a pseudospin doublet agree well in the region where nuclear potential dominates. It is concluded that the pseudospin symmetry is also well conserved for the resonant states in realistic nuclei.展开更多
The pygmy and giant dipole resonances in proton-rich nuclei 17,1817,18Ne are investigated with a fully self-consistent approach. The properties of ground states are calculated in the Skyrme Hartree–Fock with the Bard...The pygmy and giant dipole resonances in proton-rich nuclei 17,1817,18Ne are investigated with a fully self-consistent approach. The properties of ground states are calculated in the Skyrme Hartree–Fock with the Bardeen–Cooper–Schrieffer approximation to take into account the pairing correlation. The quasiparticle random phase approximation (QRPA) method is used to explore the properties of excited dipole states. In the calculations the SLy5 Skyrme interaction is employed. In addition to the giant dipole resonances, pygmy dipole resonances (PDR) are found to be located in the energy region below 10 MeV in both ^17,18Ne. The strength and transition density show that the low-lying states are typical PDR states. However, analyzing the QRPA amplitudes of proton and neutron 2 quasiparticle (2qp) configurations for a given low-lying state in ^17,18Ne, we find that the PDR state is less collective, more like a single 2qp excitation.展开更多
The isoscalar giant monopole resonances(ISGMRs)of hypernucleiAA42Ca,AA(122)Sn,andAA(210)Pb are investigated using a fully self-consistent Skyrme-Hartree-Fock plus random phase approximation method.The Skyrme-typ...The isoscalar giant monopole resonances(ISGMRs)of hypernucleiAA42Ca,AA(122)Sn,andAA(210)Pb are investigated using a fully self-consistent Skyrme-Hartree-Fock plus random phase approximation method.The Skyrme-type forces,SGII,No.5 and SAAl,are adopted to describe the nucleon-nucleon,A hyperon-nucleon and A hyperon-A hyperon(AA)interactions,respectively.For a given hyperon fraction,we find that effects of AA interaction on the properties of infinite symmetric nuclear matter and finite hypernuclei are very small.The ISGMR strengths are shifted to the high energy region when two A are added into normal nuclei.The changes are from two parts,one is due to the mean field calculations,and the other is from the residual interaction associated with A hyperons.The constrained energies are increased by about 0.5-0.7MeV,which consequently enhances the effective incompressibility modulus of hypernuclei.展开更多
We apply the recently proposed RMF(BCS)*ansatz to study the charge radii of the potassium isotopic chain up to^(52)K.It is shown that the experimental data can be reproduced rather well,qualitatively similar to the Fa...We apply the recently proposed RMF(BCS)*ansatz to study the charge radii of the potassium isotopic chain up to^(52)K.It is shown that the experimental data can be reproduced rather well,qualitatively similar to the Fayans nuclear density functional theory,but with a slightly better description of the odd-even staggerings(OES).Nonetheless,both methods fail for ^(50)K and to a lesser extent for ^(48,52)K.It is shown that if these nuclei are deformed with aβ_(20)≈−0.2,then one can obtain results consistent with experiments for both charge radii and spin-parities.We argue that beyond-mean-field studies are needed to properly describe the charge radii of these three nuclei,particularly for ^(50)K.展开更多
We examined the low-lying quadrupole states in Sn isotopes in the framework of fully self-consistent Hartree-Fock+BCS plus QRPA.We focus on the effect of the density-dependence of pairing interaction on the properties...We examined the low-lying quadrupole states in Sn isotopes in the framework of fully self-consistent Hartree-Fock+BCS plus QRPA.We focus on the effect of the density-dependence of pairing interaction on the properties of the low-lying quadrupole state.The SLy5 Skyrme interaction with surface,mixed,and volume pairings is employed in the calculations,respectively.We find that the excitation energies and the corresponding reduced electric transition probabilities of the first 2^(+) state are different,given by the three pairing interactions.The properties of the quasiparticle state,two-quasiparticle excitation energy,reduced transition amplitude,and transition densities in ^(112)Sn are analyzed in detail.Two different mechanisms,the static and dynamical effects,of the pairing correlation are also discussed.The results show that the surface,mixed,and volume pairings indeed affect the properties of the first 2^(+) state in the Sn isotopes.展开更多
In this study, shape evolution and possible shape coexistence are explored in odd-A Ne isotopes in the framework of the multidimensionally constrained relativistic-mean-field(MDC-RMF)model. By introducing ~sΛ and phy...In this study, shape evolution and possible shape coexistence are explored in odd-A Ne isotopes in the framework of the multidimensionally constrained relativistic-mean-field(MDC-RMF)model. By introducing ~sΛ and phyperons, the impurity effects on the nuclear shape, energy, size, and density distribution are investigated.For the NN interaction, the PK1 parameter set is adopted, and for the ΛN interaction, the PK1-Y1 parameter set is used. The nuclear ground state and low-lying excited states are determined by blocking the unpaired odd neutron in different orbitals around the Fermi surface. Moreover, the potential energy curves(PECs), quadrupole deformations,nuclear r.m.s. radii, binding energies, and density distributions for the core nuclei as well as the corresponding hy pernuclei are analyzed. By examining the PECs, possibilities for shape coexistence inNe and a triple shape coexistence inNe are found. In terms of the impurity effects ofΛhyperons, as noted for even-even Ne hypernuclear isotopes, the shyperon exhibits a clear shrinkage effect, which reduces the nuclear size and results in a more spherical nuclear shape. The phyperon occupying the 1/2~-[110]orbital is prolate, which causes the nuclear shape to be more prolate, and the phyperon occupying the 3/2~-[101] orbital displays an oblate shape, which drives the nuclei to be more oblate.展开更多
A fixed particle number BCS (FBCS) approach is formulated in the relativistic mean field (RMF) model. It is shown that the RMF+FBCS model obtained can describe the weak pairing limit. We calculate the ground-stat...A fixed particle number BCS (FBCS) approach is formulated in the relativistic mean field (RMF) model. It is shown that the RMF+FBCS model obtained can describe the weak pairing limit. We calculate the ground-state properties of the calcium isotopes &32-74Ca and compare the results with those obtained from the usual RMF+BCS model. Although the results are quite similar to each other, we observe the interesting phenomenon that for ^54Ca, the FBCS approach can enhance the occupation probability of the 2p1/2 single particle level and slightly increases its radius, compared with the RMF+BCS model. This leads to the unusual scenario that although ^54Ca is more bound with a spherical configuration, the corresponding size is not the most compact. We anticipate that such a phenomenon might happen for other neutron-rich nuclei and should be checked by further more systematic studies.展开更多
The isovector giant dipole resonances(IVGDR)in proton-rich Ar and Ca isotopes have been systematic-ally investigated using the resonant continuum Hartree-F ock+BCS(HF+BCS)and quasiparticle random phase ap-proximation(...The isovector giant dipole resonances(IVGDR)in proton-rich Ar and Ca isotopes have been systematic-ally investigated using the resonant continuum Hartree-F ock+BCS(HF+BCS)and quasiparticle random phase ap-proximation(QRPA)methods.The Skyrme SLy5 and density-dependent contact pairing interactions are employed in the calculations.In addition to the giant dipole resonances at energy around 18 MeV,pygmy dipole resonances(PDR)are found to be located in the energy region below 12 MeV.The calculated energy-weighted moments of PDR in nuclei close to the proton drip-line exhaust about 4%of the TRK sum rule.The strengths decrease with in-creasing mass number in each isotopic chain.The transition densities of the PDR states show that motions of pro-tons and neutrons are in phase in the interiors of nuclei,while the protons give the main contribution at the surface.By analyzing the QRPA amplitudes of proton and neutron 2-quasiparticle configurations for a given low-lying state,we find that only a few proton configurations give significant contributions.They contribute about 95%to the total QRPA amplitudes,which indicates that the collectivity of PDR states is not strong in proton-rich nuclei in the present study.展开更多
β-decay half-lives of some magic and semi-magic nuclei have been studied in a fully self-consistent Skyrme Hartree-Fock(HF) plus charge-exchange random phase approximation(RPA).The self-consistency is addressed,in th...β-decay half-lives of some magic and semi-magic nuclei have been studied in a fully self-consistent Skyrme Hartree-Fock(HF) plus charge-exchange random phase approximation(RPA).The self-consistency is addressed,in that the same Skyrme energy density functional is adopted in the calculation of ground states and Gamow-Teller excited states.First,the impact of J2 terms on the β-decay half-lives is investigated by using the SGII interaction,revealing a large influence.Subsequently,numerical calculations are performed for the selected nuclei with Skyrme energy density functionals SGII,LNS,SKX,and SAMi.Finally,comparisons to available experimental data and predictions of different theoretical models are discussed.展开更多
A recent experimental breakthrough identified the last bound neutron-rich nuclei in fluorine and neon isotopes.Based on this finding,we perform a theoretical study of Z=9,10,11,12 isotopes in the relativistic mean fie...A recent experimental breakthrough identified the last bound neutron-rich nuclei in fluorine and neon isotopes.Based on this finding,we perform a theoretical study of Z=9,10,11,12 isotopes in the relativistic mean field(RMF)model.The mean field parameters are assumed from the PK1 parameterization,and the pairing correlation is described by the particle number conservation BCS(FBCS)method recently formulated in the RMF model.We show that the FBCS approach plays an essential role in reproducing experimental results of fluorine and neon isotopes.Furthermore,we predict 39Na and 40Mg to be the last bound neutron-rich nuclei in sodium and magnesium isotopes.展开更多
Based on relativistic mean field(RMF) models, we study finite A-hypernuclei and massive neutron stars. The effective N-N interactions PK1 and TM1 are adopted, while the N-A interactions are constrained by reproducin...Based on relativistic mean field(RMF) models, we study finite A-hypernuclei and massive neutron stars. The effective N-N interactions PK1 and TM1 are adopted, while the N-A interactions are constrained by reproducing the binding energy of A-hyperon at 1 s orbit of Λ^40Ca. It is found that the A-meson couplings follow a simple relation, indicating a fixed A potential well for symmetric nuclear matter at saturation densities, i.e., around VΛ=-29.786 MeV. With those interactions, a large mass range of Λ-hypernuclei can be described well. Furthermore,the masses of PSR J1614-2230 and PSR J0348+0432 can be attained adopting the Λ-meson couplings gσΛ/gσN≥0.73,gωΛ/gωN≥0.80 for PK1 and gσΛ/gσN≥0.81,gωΛ/gωN≥0.90 for TM1, respectively. This resolves the hyperon puzzle without introducing any additional degrees of freedom.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10447102, 10475003, 10435010 and 10605004, and the Scientific Research Innovation Foundation of BUAA.
文摘Taking ^120Sn as an example, we discuss the pseudospin symmetry in the single proton resonant states by examining the energies, widths and the wavefunctions. The information of the single proton resonant states in spherical nuclei are extracted from an analytic continuation in the coupling constant method within the framework of the self-consistent relativistic mean field theory under the relativistic boundary condition. We find small energy splitting in a pair of pseudospin partners in the resonant states. The lower components of the Dirac wavefunctions of a pseudospin doublet agree well in the region where nuclear potential dominates. It is concluded that the pseudospin symmetry is also well conserved for the resonant states in realistic nuclei.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11375022,11575060,11505058 and 11435014
文摘The pygmy and giant dipole resonances in proton-rich nuclei 17,1817,18Ne are investigated with a fully self-consistent approach. The properties of ground states are calculated in the Skyrme Hartree–Fock with the Bardeen–Cooper–Schrieffer approximation to take into account the pairing correlation. The quasiparticle random phase approximation (QRPA) method is used to explore the properties of excited dipole states. In the calculations the SLy5 Skyrme interaction is employed. In addition to the giant dipole resonances, pygmy dipole resonances (PDR) are found to be located in the energy region below 10 MeV in both ^17,18Ne. The strength and transition density show that the low-lying states are typical PDR states. However, analyzing the QRPA amplitudes of proton and neutron 2 quasiparticle (2qp) configurations for a given low-lying state in ^17,18Ne, we find that the PDR state is less collective, more like a single 2qp excitation.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11575060,11775014,11505058 and 11435014
文摘The isoscalar giant monopole resonances(ISGMRs)of hypernucleiAA42Ca,AA(122)Sn,andAA(210)Pb are investigated using a fully self-consistent Skyrme-Hartree-Fock plus random phase approximation method.The Skyrme-type forces,SGII,No.5 and SAAl,are adopted to describe the nucleon-nucleon,A hyperon-nucleon and A hyperon-A hyperon(AA)interactions,respectively.For a given hyperon fraction,we find that effects of AA interaction on the properties of infinite symmetric nuclear matter and finite hypernuclei are very small.The ISGMR strengths are shifted to the high energy region when two A are added into normal nuclei.The changes are from two parts,one is due to the mean field calculations,and the other is from the residual interaction associated with A hyperons.The constrained energies are increased by about 0.5-0.7MeV,which consequently enhances the effective incompressibility modulus of hypernuclei.
基金This work is partly Supported by the National Natural Science Foundation of China(11735003,11975041,11775014,11961141004)the fundamental Research Funds for the Central Universities+1 种基金Supported by the National Natural Science Foundation of China(12135004,11635003,11961141004,12047513)the Reform and Development Project of Beijing Academy of Science and Technology(13001-2110)。
文摘We apply the recently proposed RMF(BCS)*ansatz to study the charge radii of the potassium isotopic chain up to^(52)K.It is shown that the experimental data can be reproduced rather well,qualitatively similar to the Fayans nuclear density functional theory,but with a slightly better description of the odd-even staggerings(OES).Nonetheless,both methods fail for ^(50)K and to a lesser extent for ^(48,52)K.It is shown that if these nuclei are deformed with aβ_(20)≈−0.2,then one can obtain results consistent with experiments for both charge radii and spin-parities.We argue that beyond-mean-field studies are needed to properly describe the charge radii of these three nuclei,particularly for ^(50)K.
基金Supported by the National Natural Science Foundation of China(11975096,11875027,11775014)the Fundamental Research Funds for the Central Universities(2020NTST06)。
文摘We examined the low-lying quadrupole states in Sn isotopes in the framework of fully self-consistent Hartree-Fock+BCS plus QRPA.We focus on the effect of the density-dependence of pairing interaction on the properties of the low-lying quadrupole state.The SLy5 Skyrme interaction with surface,mixed,and volume pairings is employed in the calculations,respectively.We find that the excitation energies and the corresponding reduced electric transition probabilities of the first 2^(+) state are different,given by the three pairing interactions.The properties of the quasiparticle state,two-quasiparticle excitation energy,reduced transition amplitude,and transition densities in ^(112)Sn are analyzed in detail.Two different mechanisms,the static and dynamical effects,of the pairing correlation are also discussed.The results show that the surface,mixed,and volume pairings indeed affect the properties of the first 2^(+) state in the Sn isotopes.
基金Supported by the National Natural Science Foundation of China(U2032141)the Natural Science Foundation of Henan Province(202300410479)+1 种基金the Foundation of Fundamental Research for Young Teachers of Zhengzhou University(JC202041041)the Physics Research and Development Program of Zhengzhou University(32410217)。
文摘In this study, shape evolution and possible shape coexistence are explored in odd-A Ne isotopes in the framework of the multidimensionally constrained relativistic-mean-field(MDC-RMF)model. By introducing ~sΛ and phyperons, the impurity effects on the nuclear shape, energy, size, and density distribution are investigated.For the NN interaction, the PK1 parameter set is adopted, and for the ΛN interaction, the PK1-Y1 parameter set is used. The nuclear ground state and low-lying excited states are determined by blocking the unpaired odd neutron in different orbitals around the Fermi surface. Moreover, the potential energy curves(PECs), quadrupole deformations,nuclear r.m.s. radii, binding energies, and density distributions for the core nuclei as well as the corresponding hy pernuclei are analyzed. By examining the PECs, possibilities for shape coexistence inNe and a triple shape coexistence inNe are found. In terms of the impurity effects ofΛhyperons, as noted for even-even Ne hypernuclear isotopes, the shyperon exhibits a clear shrinkage effect, which reduces the nuclear size and results in a more spherical nuclear shape. The phyperon occupying the 1/2~-[110]orbital is prolate, which causes the nuclear shape to be more prolate, and the phyperon occupying the 3/2~-[101] orbital displays an oblate shape, which drives the nuclei to be more oblate.
基金Supported by the National Natural Science Foundation of China(11522539,11735003,11775014,11375022)
文摘A fixed particle number BCS (FBCS) approach is formulated in the relativistic mean field (RMF) model. It is shown that the RMF+FBCS model obtained can describe the weak pairing limit. We calculate the ground-state properties of the calcium isotopes &32-74Ca and compare the results with those obtained from the usual RMF+BCS model. Although the results are quite similar to each other, we observe the interesting phenomenon that for ^54Ca, the FBCS approach can enhance the occupation probability of the 2p1/2 single particle level and slightly increases its radius, compared with the RMF+BCS model. This leads to the unusual scenario that although ^54Ca is more bound with a spherical configuration, the corresponding size is not the most compact. We anticipate that such a phenomenon might happen for other neutron-rich nuclei and should be checked by further more systematic studies.
基金partly Supported by the National Natural Science Foundation of China(11975096,11775014)the Fundamental Research Funds for the Central Universities(2020NTST06).
文摘The isovector giant dipole resonances(IVGDR)in proton-rich Ar and Ca isotopes have been systematic-ally investigated using the resonant continuum Hartree-F ock+BCS(HF+BCS)and quasiparticle random phase ap-proximation(QRPA)methods.The Skyrme SLy5 and density-dependent contact pairing interactions are employed in the calculations.In addition to the giant dipole resonances at energy around 18 MeV,pygmy dipole resonances(PDR)are found to be located in the energy region below 12 MeV.The calculated energy-weighted moments of PDR in nuclei close to the proton drip-line exhaust about 4%of the TRK sum rule.The strengths decrease with in-creasing mass number in each isotopic chain.The transition densities of the PDR states show that motions of pro-tons and neutrons are in phase in the interiors of nuclei,while the protons give the main contribution at the surface.By analyzing the QRPA amplitudes of proton and neutron 2-quasiparticle configurations for a given low-lying state,we find that only a few proton configurations give significant contributions.They contribute about 95%to the total QRPA amplitudes,which indicates that the collectivity of PDR states is not strong in proton-rich nuclei in the present study.
基金Supported by the National Natural Science Foundation of China(11975096,11805280,11775014,11635003,11161130520)National Basic Research Program of China(2010CB832903)+1 种基金European Commission’s 7th Framework Programme(Fp7-PEOPLE-2010-IRSES)under Grant Agreement Project(269131)Continuous Basic Scientific Research Project(WDJC-2019-13)。
文摘β-decay half-lives of some magic and semi-magic nuclei have been studied in a fully self-consistent Skyrme Hartree-Fock(HF) plus charge-exchange random phase approximation(RPA).The self-consistency is addressed,in that the same Skyrme energy density functional is adopted in the calculation of ground states and Gamow-Teller excited states.First,the impact of J2 terms on the β-decay half-lives is investigated by using the SGII interaction,revealing a large influence.Subsequently,numerical calculations are performed for the selected nuclei with Skyrme energy density functionals SGII,LNS,SKX,and SAMi.Finally,comparisons to available experimental data and predictions of different theoretical models are discussed.
基金Partly supported by the National Natural Science Foundation of China(11735003,11975041,11775014,11961141004)the fundamental Research Funds for the Central Universities。
文摘A recent experimental breakthrough identified the last bound neutron-rich nuclei in fluorine and neon isotopes.Based on this finding,we perform a theoretical study of Z=9,10,11,12 isotopes in the relativistic mean field(RMF)model.The mean field parameters are assumed from the PK1 parameterization,and the pairing correlation is described by the particle number conservation BCS(FBCS)method recently formulated in the RMF model.We show that the FBCS approach plays an essential role in reproducing experimental results of fluorine and neon isotopes.Furthermore,we predict 39Na and 40Mg to be the last bound neutron-rich nuclei in sodium and magnesium isotopes.
基金Supported by National Natural Science Foundation of China(11525524,11505157,11375022,11705163,11621131001)National Key Basic Research Program of China(2013CB834400)+3 种基金the Physics Research and Development Program of Zhengzhou University(32410017)the Office of Nuclear Physics in the U.S.Dept.of Energysupported by the HPC Cluster of SKLTP/ITP-CASthe Supercomputing Center,CNIC,of the CAS
文摘Based on relativistic mean field(RMF) models, we study finite A-hypernuclei and massive neutron stars. The effective N-N interactions PK1 and TM1 are adopted, while the N-A interactions are constrained by reproducing the binding energy of A-hyperon at 1 s orbit of Λ^40Ca. It is found that the A-meson couplings follow a simple relation, indicating a fixed A potential well for symmetric nuclear matter at saturation densities, i.e., around VΛ=-29.786 MeV. With those interactions, a large mass range of Λ-hypernuclei can be described well. Furthermore,the masses of PSR J1614-2230 and PSR J0348+0432 can be attained adopting the Λ-meson couplings gσΛ/gσN≥0.73,gωΛ/gωN≥0.80 for PK1 and gσΛ/gσN≥0.81,gωΛ/gωN≥0.90 for TM1, respectively. This resolves the hyperon puzzle without introducing any additional degrees of freedom.