The quark potential model is extended to include the sea quark excitation using the random phase approximation. The effective quark interaction preserves the important QCD properties — chiral symmetry and confinement...The quark potential model is extended to include the sea quark excitation using the random phase approximation. The effective quark interaction preserves the important QCD properties — chiral symmetry and confinement simultaneously. A primary qualitative analysis shows that the π meson as a well-known typical Goldstone boson and the other mesons made up of valence quark pair such as the ρ meson can also be described in this extended quark potential model.展开更多
By using the rigorous spectral representation of relativistic random phase approximation, the low-lying excitation of finite nuclei and its longitudinal response function for quasielastic electron scattering are calcu...By using the rigorous spectral representation of relativistic random phase approximation, the low-lying excitation of finite nuclei and its longitudinal response function for quasielastic electron scattering are calculated in the σ-ω model of quantum hadrodynamics. It is shown that the reproduction of the correct order of the 1- and 3- excitation states of 16O is due to the contribution of the exchange vertex. There is no significant influence of the retardation effect on the low-lying excitation states. In contrast, the retardation effect plays an important role in the electron scattering process of nuclei. The theoretical longitudinal responses of 12C and 40Ca, including the contributions of the exchange vertex and the retardation effect, are suppressed and reproduce the experimental data better than the results excluding them.展开更多
We apply the derivative coupling model with ZM and ZM3 parameters to investigate the longitudinal response function in quasielastic electron scattering in the relativistic random phase approximation. The non-spectral ...We apply the derivative coupling model with ZM and ZM3 parameters to investigate the longitudinal response function in quasielastic electron scattering in the relativistic random phase approximation. The non-spectral method is chosen to describe the nucleon Green＇s function in a finite nucleus. Some remarks have been made in conclusion.展开更多
The random phase approximation is applied to the coupled-cluster expansions of lattice gauge theory (LGT). Using this method, wavefunctions are approximated by linear combination of graphs consisting of only one conne...The random phase approximation is applied to the coupled-cluster expansions of lattice gauge theory (LGT). Using this method, wavefunctions are approximated by linear combination of graphs consisting of only one connected Wilson loop. We study the excited state energy and wavefunction in (2+1)-D SU(3) LGT up to the third order. The glueball mass shows a good scaling behavior.展开更多
In this paper, the generalized oscillator strengths (GOSs) of excitations of atomic sodium from ground state to 2p63s0 (3p, 4p, 5p, 6p) states, immersed in Debye plasma, were calculated by using wavefunctions which we...In this paper, the generalized oscillator strengths (GOSs) of excitations of atomic sodium from ground state to 2p63s0 (3p, 4p, 5p, 6p) states, immersed in Debye plasma, were calculated by using wavefunctions which were obtained numerically from the restricted Hartree-Fock (RHF) equation. This RHF equation employs the local density approach for exchange interactions including plasma Debye screening. Theoretical RHF and random phase approximation with exchange (RPAE) velocity calculations have shown that the GOSs for excitations to 3 s0(3 p,4 p,5 p,6 p)depend on the plasma Debye screening effects, as shown by the reduction in the GOS amplitude with decreasing Debye length λD. The agreement between the present RPAE V results for the transitions 3 s→3 s0(3 p,4 p,5 p)and the length calculations of Martínez-Flores was satisfactory. Correlation effects were found quite to be significant in the vicinity of the maxima of the GOS of the 3 s→3 s0(4 p,5 p,6 p)excitations by using the RPAE V approach. We note the poor influence of many electron correlations on the GOS of (3 s→3 p)transition with the same principal quantum number. Finally, we comment that the RPAE V calculations are useful in investigating electron correlation effects on the transition GOS of atomic sodium planted in Debye plasma. The present velocity results also reveal that the 3 s→3 s0(5p, 6p)transition GOSs tend to be delocalized due to more significant screening effects at Debye lengths λD=20and 30 a.u. for excited subshells 5p and 6p, respectively. We report here novel results of GOS for 3 s→3 s06ptransition obtained from different Debye lengths.展开更多
The generalized oscillator strengths (GOSs) of 2p63s0 (3p, 4p, 5p, 6p) states excited from sodium ground state in Debye plasma, are studied by two kinds of theoretical approaches: the restricted Hartree-Fock (RHF) met...The generalized oscillator strengths (GOSs) of 2p63s0 (3p, 4p, 5p, 6p) states excited from sodium ground state in Debye plasma, are studied by two kinds of theoretical approaches: the restricted Hartree-Fock (RHF) method and the random phase approximation with exchange (RPAE). Wavefunctions of the ground state and the excited states are calculated numerically from the RHF equation, employing the local density approach for exchange interaction including, in extension, plasma screening effects. The GOSs have been computed by using these wavefunctions. The results of RHF and RPAE calculations of the GOS for different Debye lengths have been reported for sodium dipole excitation to 3s0 (3p, 4p, 5p, 6p). We show, in this study, that RPAE results for values of Debye length D = 30, 100, ∞ are in excellent agreement with those found by other authors. The results of RPAE calculations show that correlation effects are quite significant around the maxima GOS for the excitations to 3s0 (4p, 5p, 6p) but are found to have no great influence in the GOS for the dipole excitation to 3s03p. We find that the amplitude of the GOS has noticeably been reduced in going from higher to lower Debye length. We’ve observed here that the peak of the GOS shifts towards a small momentum transfer when the value D = 20 a.u is taken. These results show an important influence of the Debye plasma screening interactions on the GOS as the screening Debye length is decreased.展开更多
Ferromagnetism in the one-dimensional Hubbard model with the next-nearest-neighbor hopping is explored by using the exact-diagonalization method in a small cluster and the equation-of-motion method in the thermodynami...Ferromagnetism in the one-dimensional Hubbard model with the next-nearest-neighbor hopping is explored by using the exact-diagonalization method in a small cluster and the equation-of-motion method in the thermodynamic limit with electron density n = 3/2. With these two complementary methods, it is found that an intermediate value of the next-nearest- neighbor hopping amplitude tl tends to stabilize the fully polarized ferromagnetic state under the condition that the on-site coulomb interaction U is sufficiently large in our model. The ground-state phase diagram of the model is presented in the tl-U plane.展开更多
The isovector giant dipole resonance in Ca isotopes is investigated in the framework of the fully consistent relativistic random phase approximation. The calculations are performed in an effective Lagrangian with a pa...The isovector giant dipole resonance in Ca isotopes is investigated in the framework of the fully consistent relativistic random phase approximation. The calculations are performed in an effective Lagrangian with a parameter set , which was proposed for satisfactorily describing nuclear ground state properties. It is found that a soft isovector dipole mode for Ca isotopes near drip lines exists at energy around . The soft dipole states are mainly due to the excitation of the weakly bound and pure neutron (proton) states near Fermi surface as well as the correlation of isoscalar and isovector operators. For nuclei with the extreme value of , the contributions of isoscalar mesons in the isovector mode play a non-negligible role.展开更多
We investigate the effects of theσmeson mass(m_(σ)),symmetry energy,and slope of the symmetry energy on the neutron star core-crust transition density and the crustal moment of inertia(ΔI/I)in the nonlinear relativ...We investigate the effects of theσmeson mass(m_(σ)),symmetry energy,and slope of the symmetry energy on the neutron star core-crust transition density and the crustal moment of inertia(ΔI/I)in the nonlinear relativistic Hartree approach(RHA),which includes vacuum polarization.Although the core-crust transition density(ρ_(t)),pressure(P_(t)),and neutron star radius(R),which are all dependent on the symmetry energy,contribute to determiningΔI/I,we find that changing only the slope of symmetry energy within a reasonable range is not sufficient to reachΔI/I≥7%to achieve the large glitches of the Vela pulsar.However,since all three factors(ρ_(t),P_(t),and R)increase with the increase in mσthrough scalar vacuum polarization,adjusting mσcan easily achieveΔI/I≥7%.展开更多
We conduct a new investigation of the correlation at saturation(subsaturation)density between the density dependence of symmetry energy and the percentage of the energy-weighted sum rule(EWSR)exhausted by pygmy dipole...We conduct a new investigation of the correlation at saturation(subsaturation)density between the density dependence of symmetry energy and the percentage of the energy-weighted sum rule(EWSR)exhausted by pygmy dipole resonances(PDR)in^(68)Ni and^(132)Sn.The calculations are performed within the Skyrme HF(or HF+BCS)plus random phase approximation(RPA)(or quasiparticle RPA)problem using SAMi-J effective interactions.The effect of pairing on the dipole strength distribution of^(68)Ni and density dependence of the symmetry energy is discussed.Slope parameter L and symmetry energy J at saturation(subsaturation)density are 41.8−90.2 MeV(39.3−64.1 MeV)and 28.0−32.5 MeV(23.0−23.8 MeV),respectively.They are consistent with the currently accepted values except for J at subsaturation density,which is slightly lower than the values obtained from nuclear mass difference measurements and electric dipole polarizability data.展开更多
The effects of the tensor force on the and decay nuclear matrix elements(NMEs)of,,,and are studied using the Hartree-Fock-Bogoliubov(HFB)plus proton-neutron quasi-particle random phase approximation(pnQRPA)model based...The effects of the tensor force on the and decay nuclear matrix elements(NMEs)of,,,and are studied using the Hartree-Fock-Bogoliubov(HFB)plus proton-neutron quasi-particle random phase approximation(pnQRPA)model based on the Skyrme energy density functional.We include the full spectra of intermediate states with up to the energy cutoff E=60 MeV,which is sufficient for convergence of NME calculations.The isovector(IV)pairing and tensor interactions are considered in both HFB and QRPA calculations,while the isoscalar(IS)pairing interaction is included only in QRPA calculations.We found that the tensor force shifts Gamow-Teller(GT)transition strengths substantially to low-energy regions and enhances the decay NME.The inclusion of tensor force enhances the NME by approximately 13%for and and 30%for and,for a fixed IS pairing strength.We found that the intermediate 2-state makes an important contribution to the NME,which is slightly enhanced by the inclusion of the tensor force.We also found that the contribution of the state makes important differences through the inclusion of the tensor force,which enhances the contribution largely.However when the IS pairing strength is increased,the contributions from 1+states are rapidly reduced to be very small,resulting in even negative contributions.Thus,tensor and IS pairing effects cancel each other,making the net effect on the NME relatively small.Due to this cancellation,if the IS pairing strength is optimized separately for cases with and without the tensor interaction to reproduce the experimental NME,the consequent NME with the tensor interaction is close to that without the tensor interaction within a 10%difference.展开更多
The continuum quasiparticle random phase approximation(CQRPA),which includes the Skyrme interaction for both groundand excited-state calculations,is extended in a more consistent manner in the present work.The emergen...The continuum quasiparticle random phase approximation(CQRPA),which includes the Skyrme interaction for both groundand excited-state calculations,is extended in a more consistent manner in the present work.The emergence,evolution,and origin of pygmy monopole strengths along the even-even Ni isotopes were investigated carefully within consistent Skyrme HF+BCS and CQRPA models.The SLy5 Skyrme interaction and density-dependent zero-range pairing interactions were adopted in the calculations.No pygmy monopole strength was observed in^(70-78)Ni.However,pronounced pygmy monopole strengths are clearly observed in^(80-84)Ni,which are attributed mainly to the neutron excitations from weakly bound orbitals into the continuum.The neutron states involved in the pygmy monopole strength include 1 g_(9∕2),2 d_(5∕2),3 s_(1∕2)and 2 d_(3∕2).We suggest that more efforts from experimental investigations of pygmy monopole resonance should be made to confirm or disprove the predictions from models in the future.展开更多
The self-consistent random phase approximation (RPA) approach with the residual interaction derived from a relativistic pointcoupling energy functional is applied to evaluate the isospin symmetry-breaking corrections ...The self-consistent random phase approximation (RPA) approach with the residual interaction derived from a relativistic pointcoupling energy functional is applied to evaluate the isospin symmetry-breaking corrections δ c for the 0+ → 0+ superallowed Fermi transitions.With these δ c values,together with the available experimental f t values and the improved radiative corrections,the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix is examined.Even with the consideration of uncertainty,the sum of squared top-row elements has been shown to deviate from the unitarity condition by 0.1% for all the employed relativistic energy functionals.展开更多
The charge exchange spin-dipole(SD) excitations of ^(90)Zr are studied using the Skyrme Hartee-Fock plus proton-neutron random phase approximation with SAMi-J interactions.The experimental value of the model-independe...The charge exchange spin-dipole(SD) excitations of ^(90)Zr are studied using the Skyrme Hartee-Fock plus proton-neutron random phase approximation with SAMi-J interactions.The experimental value of the model-independent sum rule obtained from the SD strength distributions of ^(90)Zr(p,n) ^(90)Nb and ^(90)Zr(n,p) ^(90)Y is used to deduce the neutron skin thickness.The neutron skin thickness Δr_(np) of ^(90)Zr is extracted as 0.083±0.032 fm,which is similar to the results of other studies.Based on the correlation analysis of the neutron skin thickness Δr_(np) and the nuclear symmetry energy J as well as its slope parameter L,a constraint from the extracted Δr_(np) leads to the limitation of J to 29.2±2.6 MeV and L to 53.3±28.2 MeV.展开更多
Based on the random phase approximation calculation in two-orbital honeycomb lattice model,we investigate the pairing symmetry of Ni-based transition-metal trichalcogenides by electron doping access to type-II van Hov...Based on the random phase approximation calculation in two-orbital honeycomb lattice model,we investigate the pairing symmetry of Ni-based transition-metal trichalcogenides by electron doping access to type-II van Hove singularities(vHs).We find that chiral even-parity d+id-wave(Eg)state is suppressed by odd-parity p+ip-wave(Eu)state when electron doping approaches the type-II vHs.The type-II vHs peak in density of states(DOS)enables to strengthen the ferromagnetic fluctuation,which is responsible for triplet pairing.The competition between antiferromagnetic and ferromagnetic fluctuation results in pairing phase transition from singlet to triplet pairing.The Ni-based transition-metal trichalcogenides provide a promising platform to unconventional superconductor emerging from electronic DOS.展开更多
Using partially restored isospin symmetry,we calculate the nuclear matrix elements for a special decay mode of a two-neutrino double beta decay–the decay to the first 2+excited states.Employing the realistic CD–Bonn...Using partially restored isospin symmetry,we calculate the nuclear matrix elements for a special decay mode of a two-neutrino double beta decay–the decay to the first 2+excited states.Employing the realistic CD–Bonn nuclear force,we analyze the dependence of the nuclear matrix elements on the isovector and isoscalar parts of proton–neutron particle–particle interactions.The dependence on the different nuclear matrix elements is observed,and the results are explained.We also provide the phase space factors using numerical electron wavefunctions and properly chosen excitation energies.Finally,we present our results for the half-lives of this decay mode for different nuclei.展开更多
The pygmy dipole resonance（PDR） of nickel isotopes is studied using the deformed random phase approximation method. The isoscalar character of the pygmy resonance is confirmed, and the correlation between the pygmy ...The pygmy dipole resonance（PDR） of nickel isotopes is studied using the deformed random phase approximation method. The isoscalar character of the pygmy resonance is confirmed, and the correlation between the pygmy resonance and neutron skin thickness is discussed. Our investigation shows a linear correlation between PDR integral cross section and neutron skin thickness when the excess neutrons lie in pf orbits, with a correlation rate of about 0.27 fm^（-1）. However, in more neutron-rich nickel isotopes, the growth of the pygmy dipole resonance is stagnant. Although the neutron skin thickness increases, the whole skin is not active. There is an inertial part in the nuclei^（70-78）Ni which does not participate in the pygmy resonance actively and as a result, contributes little to the photo-absorption cross section.展开更多
文摘The quark potential model is extended to include the sea quark excitation using the random phase approximation. The effective quark interaction preserves the important QCD properties — chiral symmetry and confinement simultaneously. A primary qualitative analysis shows that the π meson as a well-known typical Goldstone boson and the other mesons made up of valence quark pair such as the ρ meson can also be described in this extended quark potential model.
基金Supported by National Nature Science Foundation of China (10775059)Specialized Research Fund for the Doctoral Program of the Higher Education of China (20070183133)
文摘By using the rigorous spectral representation of relativistic random phase approximation, the low-lying excitation of finite nuclei and its longitudinal response function for quasielastic electron scattering are calculated in the σ-ω model of quantum hadrodynamics. It is shown that the reproduction of the correct order of the 1- and 3- excitation states of 16O is due to the contribution of the exchange vertex. There is no significant influence of the retardation effect on the low-lying excitation states. In contrast, the retardation effect plays an important role in the electron scattering process of nuclei. The theoretical longitudinal responses of 12C and 40Ca, including the contributions of the exchange vertex and the retardation effect, are suppressed and reproduce the experimental data better than the results excluding them.
基金Supported by National Basic Research Program of China (2009CB824800)National Natural Science Foundation of China (11103001)+1 种基金Hunan Provincial Natural Science Foundation of China (11JJ3006)Research Grants of Changsha University of Science and Technology,the Construct Program of the Key Discipline in Hunan Province and Aid Program for Science and Technology Innovative Research Team in Higher Educational Institute of Hunan Province
文摘We apply the derivative coupling model with ZM and ZM3 parameters to investigate the longitudinal response function in quasielastic electron scattering in the relativistic random phase approximation. The non-spectral method is chosen to describe the nucleon Green＇s function in a finite nucleus. Some remarks have been made in conclusion.
文摘The random phase approximation is applied to the coupled-cluster expansions of lattice gauge theory (LGT). Using this method, wavefunctions are approximated by linear combination of graphs consisting of only one connected Wilson loop. We study the excited state energy and wavefunction in (2+1)-D SU(3) LGT up to the third order. The glueball mass shows a good scaling behavior.
文摘In this paper, the generalized oscillator strengths (GOSs) of excitations of atomic sodium from ground state to 2p63s0 (3p, 4p, 5p, 6p) states, immersed in Debye plasma, were calculated by using wavefunctions which were obtained numerically from the restricted Hartree-Fock (RHF) equation. This RHF equation employs the local density approach for exchange interactions including plasma Debye screening. Theoretical RHF and random phase approximation with exchange (RPAE) velocity calculations have shown that the GOSs for excitations to 3 s0(3 p,4 p,5 p,6 p)depend on the plasma Debye screening effects, as shown by the reduction in the GOS amplitude with decreasing Debye length λD. The agreement between the present RPAE V results for the transitions 3 s→3 s0(3 p,4 p,5 p)and the length calculations of Martínez-Flores was satisfactory. Correlation effects were found quite to be significant in the vicinity of the maxima of the GOS of the 3 s→3 s0(4 p,5 p,6 p)excitations by using the RPAE V approach. We note the poor influence of many electron correlations on the GOS of (3 s→3 p)transition with the same principal quantum number. Finally, we comment that the RPAE V calculations are useful in investigating electron correlation effects on the transition GOS of atomic sodium planted in Debye plasma. The present velocity results also reveal that the 3 s→3 s0(5p, 6p)transition GOSs tend to be delocalized due to more significant screening effects at Debye lengths λD=20and 30 a.u. for excited subshells 5p and 6p, respectively. We report here novel results of GOS for 3 s→3 s06ptransition obtained from different Debye lengths.
文摘The generalized oscillator strengths (GOSs) of 2p63s0 (3p, 4p, 5p, 6p) states excited from sodium ground state in Debye plasma, are studied by two kinds of theoretical approaches: the restricted Hartree-Fock (RHF) method and the random phase approximation with exchange (RPAE). Wavefunctions of the ground state and the excited states are calculated numerically from the RHF equation, employing the local density approach for exchange interaction including, in extension, plasma screening effects. The GOSs have been computed by using these wavefunctions. The results of RHF and RPAE calculations of the GOS for different Debye lengths have been reported for sodium dipole excitation to 3s0 (3p, 4p, 5p, 6p). We show, in this study, that RPAE results for values of Debye length D = 30, 100, ∞ are in excellent agreement with those found by other authors. The results of RPAE calculations show that correlation effects are quite significant around the maxima GOS for the excitations to 3s0 (4p, 5p, 6p) but are found to have no great influence in the GOS for the dipole excitation to 3s03p. We find that the amplitude of the GOS has noticeably been reduced in going from higher to lower Debye length. We’ve observed here that the peak of the GOS shifts towards a small momentum transfer when the value D = 20 a.u is taken. These results show an important influence of the Debye plasma screening interactions on the GOS as the screening Debye length is decreased.
基金supported by the State Key Laboratory of Software Development Environment,China(Grant No.SKLSDE-2013ZX-21)the National Natural Science Foundation of China(Grant No.50971011)the Beijing Natural Science Foundation,China(Grant No.1102025)
文摘Ferromagnetism in the one-dimensional Hubbard model with the next-nearest-neighbor hopping is explored by using the exact-diagonalization method in a small cluster and the equation-of-motion method in the thermodynamic limit with electron density n = 3/2. With these two complementary methods, it is found that an intermediate value of the next-nearest- neighbor hopping amplitude tl tends to stabilize the fully polarized ferromagnetic state under the condition that the on-site coulomb interaction U is sufficiently large in our model. The ground-state phase diagram of the model is presented in the tl-U plane.
文摘The isovector giant dipole resonance in Ca isotopes is investigated in the framework of the fully consistent relativistic random phase approximation. The calculations are performed in an effective Lagrangian with a parameter set , which was proposed for satisfactorily describing nuclear ground state properties. It is found that a soft isovector dipole mode for Ca isotopes near drip lines exists at energy around . The soft dipole states are mainly due to the excitation of the weakly bound and pure neutron (proton) states near Fermi surface as well as the correlation of isoscalar and isovector operators. For nuclei with the extreme value of , the contributions of isoscalar mesons in the isovector mode play a non-negligible role.
基金Supported in part by the National Natural Science Foundation of China (11775049,12375112)。
文摘We investigate the effects of theσmeson mass(m_(σ)),symmetry energy,and slope of the symmetry energy on the neutron star core-crust transition density and the crustal moment of inertia(ΔI/I)in the nonlinear relativistic Hartree approach(RHA),which includes vacuum polarization.Although the core-crust transition density(ρ_(t)),pressure(P_(t)),and neutron star radius(R),which are all dependent on the symmetry energy,contribute to determiningΔI/I,we find that changing only the slope of symmetry energy within a reasonable range is not sufficient to reachΔI/I≥7%to achieve the large glitches of the Vela pulsar.However,since all three factors(ρ_(t),P_(t),and R)increase with the increase in mσthrough scalar vacuum polarization,adjusting mσcan easily achieveΔI/I≥7%.
基金Partly Supported by the National Natural Science Foundation of China(12275025,11975096,11875027,11775014)the Fundamental Research Funds for the Central Universities(2020NTST06)。
文摘We conduct a new investigation of the correlation at saturation(subsaturation)density between the density dependence of symmetry energy and the percentage of the energy-weighted sum rule(EWSR)exhausted by pygmy dipole resonances(PDR)in^(68)Ni and^(132)Sn.The calculations are performed within the Skyrme HF(or HF+BCS)plus random phase approximation(RPA)(or quasiparticle RPA)problem using SAMi-J effective interactions.The effect of pairing on the dipole strength distribution of^(68)Ni and density dependence of the symmetry energy is discussed.Slope parameter L and symmetry energy J at saturation(subsaturation)density are 41.8−90.2 MeV(39.3−64.1 MeV)and 28.0−32.5 MeV(23.0−23.8 MeV),respectively.They are consistent with the currently accepted values except for J at subsaturation density,which is slightly lower than the values obtained from nuclear mass difference measurements and electric dipole polarizability data.
基金Supported by the National Natural Science Foundation of China(11575120,11822504,12075104)National Key Research and Development(R&D)programe of China(2021YFA1601500)+2 种基金Science Specialty Program of Sichuan University(2020SCUNL210)the support from Chinese Academy of Sciences for the project of Young Scientists in Basic Research(YSBR-099)"From 0 to 1 innovative"program.This work was partially supported by JSPS KAKENHI(JP19K03858)。
文摘The effects of the tensor force on the and decay nuclear matrix elements(NMEs)of,,,and are studied using the Hartree-Fock-Bogoliubov(HFB)plus proton-neutron quasi-particle random phase approximation(pnQRPA)model based on the Skyrme energy density functional.We include the full spectra of intermediate states with up to the energy cutoff E=60 MeV,which is sufficient for convergence of NME calculations.The isovector(IV)pairing and tensor interactions are considered in both HFB and QRPA calculations,while the isoscalar(IS)pairing interaction is included only in QRPA calculations.We found that the tensor force shifts Gamow-Teller(GT)transition strengths substantially to low-energy regions and enhances the decay NME.The inclusion of tensor force enhances the NME by approximately 13%for and and 30%for and,for a fixed IS pairing strength.We found that the intermediate 2-state makes an important contribution to the NME,which is slightly enhanced by the inclusion of the tensor force.We also found that the contribution of the state makes important differences through the inclusion of the tensor force,which enhances the contribution largely.However when the IS pairing strength is increased,the contributions from 1+states are rapidly reduced to be very small,resulting in even negative contributions.Thus,tensor and IS pairing effects cancel each other,making the net effect on the NME relatively small.Due to this cancellation,if the IS pairing strength is optimized separately for cases with and without the tensor interaction to reproduce the experimental NME,the consequent NME with the tensor interaction is close to that without the tensor interaction within a 10%difference.
基金partly supported by the National Natural Science Foundation of China(Nos.12275025,11975096,12135004,and 11961141004)the Fundamental Research Funds for the Central Universities(No.2020NTST06)。
文摘The continuum quasiparticle random phase approximation(CQRPA),which includes the Skyrme interaction for both groundand excited-state calculations,is extended in a more consistent manner in the present work.The emergence,evolution,and origin of pygmy monopole strengths along the even-even Ni isotopes were investigated carefully within consistent Skyrme HF+BCS and CQRPA models.The SLy5 Skyrme interaction and density-dependent zero-range pairing interactions were adopted in the calculations.No pygmy monopole strength was observed in^(70-78)Ni.However,pronounced pygmy monopole strengths are clearly observed in^(80-84)Ni,which are attributed mainly to the neutron excitations from weakly bound orbitals into the continuum.The neutron states involved in the pygmy monopole strength include 1 g_(9∕2),2 d_(5∕2),3 s_(1∕2)and 2 d_(3∕2).We suggest that more efforts from experimental investigations of pygmy monopole resonance should be made to confirm or disprove the predictions from models in the future.
基金supported by the National Natural Science Foundation of China (Grant No.10947013)the Fundamental Research Funds for the Central Universities (Grant No.XDJK2010B007)the SWU Initial Research Foundation Grant to Doctor (Grant No.SWU109011)
文摘The self-consistent random phase approximation (RPA) approach with the residual interaction derived from a relativistic pointcoupling energy functional is applied to evaluate the isospin symmetry-breaking corrections δ c for the 0+ → 0+ superallowed Fermi transitions.With these δ c values,together with the available experimental f t values and the improved radiative corrections,the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix is examined.Even with the consideration of uncertainty,the sum of squared top-row elements has been shown to deviate from the unitarity condition by 0.1% for all the employed relativistic energy functionals.
基金Supported by the National Natural Science Foundation of China (12275025, 11975096, 12135004, 11961141004, 11635003)the Fundamental Research Funds for the Central Universities (2020NTST06)。
文摘The charge exchange spin-dipole(SD) excitations of ^(90)Zr are studied using the Skyrme Hartee-Fock plus proton-neutron random phase approximation with SAMi-J interactions.The experimental value of the model-independent sum rule obtained from the SD strength distributions of ^(90)Zr(p,n) ^(90)Nb and ^(90)Zr(n,p) ^(90)Y is used to deduce the neutron skin thickness.The neutron skin thickness Δr_(np) of ^(90)Zr is extracted as 0.083±0.032 fm,which is similar to the results of other studies.Based on the correlation analysis of the neutron skin thickness Δr_(np) and the nuclear symmetry energy J as well as its slope parameter L,a constraint from the extracted Δr_(np) leads to the limitation of J to 29.2±2.6 MeV and L to 53.3±28.2 MeV.
文摘Based on the random phase approximation calculation in two-orbital honeycomb lattice model,we investigate the pairing symmetry of Ni-based transition-metal trichalcogenides by electron doping access to type-II van Hove singularities(vHs).We find that chiral even-parity d+id-wave(Eg)state is suppressed by odd-parity p+ip-wave(Eu)state when electron doping approaches the type-II vHs.The type-II vHs peak in density of states(DOS)enables to strengthen the ferromagnetic fluctuation,which is responsible for triplet pairing.The competition between antiferromagnetic and ferromagnetic fluctuation results in pairing phase transition from singlet to triplet pairing.The Ni-based transition-metal trichalcogenides provide a promising platform to unconventional superconductor emerging from electronic DOS.
基金Supported by National Natural Science Foundation of China(11505078,1164730)“Light of West China”Program and key research program(XDPB09-2)from Chinese Academy of Sciences。
文摘Using partially restored isospin symmetry,we calculate the nuclear matrix elements for a special decay mode of a two-neutrino double beta decay–the decay to the first 2+excited states.Employing the realistic CD–Bonn nuclear force,we analyze the dependence of the nuclear matrix elements on the isovector and isoscalar parts of proton–neutron particle–particle interactions.The dependence on the different nuclear matrix elements is observed,and the results are explained.We also provide the phase space factors using numerical electron wavefunctions and properly chosen excitation energies.Finally,we present our results for the half-lives of this decay mode for different nuclei.
基金Supported by National Science Foundation of China
文摘The pygmy dipole resonance（PDR） of nickel isotopes is studied using the deformed random phase approximation method. The isoscalar character of the pygmy resonance is confirmed, and the correlation between the pygmy resonance and neutron skin thickness is discussed. Our investigation shows a linear correlation between PDR integral cross section and neutron skin thickness when the excess neutrons lie in pf orbits, with a correlation rate of about 0.27 fm^（-1）. However, in more neutron-rich nickel isotopes, the growth of the pygmy dipole resonance is stagnant. Although the neutron skin thickness increases, the whole skin is not active. There is an inertial part in the nuclei^（70-78）Ni which does not participate in the pygmy resonance actively and as a result, contributes little to the photo-absorption cross section.
