Low-energy isovector and isoscalar dipole response in neutron-rich nuclei

Abstract

The self-consistent random phase approximation (RPA), based on the framework of relativistic energy density functionals, is employed in the study of isovector and isoscalar dipole response in ${}^{68}$Ni, ${}^{132}$Sn, and ${}^{208}$Pb. The evolution of pygmy dipole states (PDS) in the region of low excitation energies is analyzed as a function of the density-dependence of the symmetry energy for a set of relativistic effective interactions. The occurrence of PDS is predicted in the response to both the isovector and isoscalar dipole operators, and its strength is enhanced with the increase of the symmetry energy at saturation and the slope of the symmetry energy. In both channels the PDS exhausts a relatively small fraction of the energy-weighted sum rule but a much larger percentage of the inverse energy-weighted sum rule. For the isovector dipole operator the reduced transition probability $B(E1)$ of the PDS is generally small because of pronounced cancellation of neutron and proton partial contributions. The isoscalar reduced transition amplitude is predominantly determined by neutron particle-hole configurations, most of which add coherently, and this results in a collective response of the PDS to the isoscalar dipole operator.

submitted to Phys. Rev. C

References in corpus (25)

• Measurement of the Neutron Radius of 208Pb Through Parity-Violation in Electron Scattering
• Exotic modes of excitation in atomic nuclei far from stability
• Complete electric dipole response and the neutron skin in 208Pb
• Constraints on the symmetry energy and on neutron skins from the pygmy resonances in 68Ni and 132Sn
• Pygmy dipole resonance as a constraint on the neutron skin of heavy nuclei
• Isospin Character of the Pygmy Dipole Resonance in 124Sn
• Investigation of Pygmy Dipole Resonances in the Tin Region
• Spin-isospin resonances: A self-consistent covariant description
• Pygmy Resonances and Neutron Skins
• Relativistic quasiparticle time blocking approximation. Dipole response of open-shell nuclei
• Pygmy dipole strength in 90Zr
• Self-consistent description of multipole strength: systematic calculations
• Emergence of pygmy dipole resonances: Magic numbers and neutron skins
• Low-lying dipole response: isospin character and collectivity in ${}^{68}$Ni, ${}^{132}$Sn and ${}^{208}$Pb
• Fragmentation and systematics of the Pygmy Dipole Resonance in the stable N=82 isotones
• Relativistic quasiparticle time blocking approximation. II. Pygmy dipole resonance in neutron-rich nuclei
• Low-lying dipole response in the stable ${}^{40,48}$Ca nuclei with the second random-phase approximation
• Relativistic RPA plus phonon-coupling analysis of pygmy dipole resonances
• Microscopic linear response calculations based on the Skyrme functional plus the pairing contribution
• Low-energy dipole excitations in neon isotopes and N=16 isotones within the quasiparticle random phase approximation and the Gogny force
• Pygmy resonance and torus mode within Vlasov dynamics
• Isoscalar dipole coherence at low energies and forbidden E1 strength
• The quest for novel modes of excitation in exotic nuclei
• Core polarization for the electric quadrupole moment of neutron-rich Aluminum isotopes
• Relativistic QRPA description of isoscalar compression modes in open-shell nuclei in the A$\approx$60 mass region

Cited by in corpus (40)

• Nuclear Equation of State from ground and collective excited state properties of nuclei
• Symmetry energy from the nuclear collective motion: constraints from dipole, quadrupole, monopole and spin-dipole resonances
• Information content of the low-energy electric dipole strength: correlation analysis
• Low-energy electric dipole response in 120Sn
• Radial basis function approach in nuclear mass predictions
• Low-energy dipole strength in 112,120Sn
• Population of dipole states via isoscalar probes: the splitting of pygmy dipole resonance in ${}^{124}$Sn}
• Constraining simultaneously nuclear symmetry energy and neutron-proton effective mass splitting with nucleus giant resonances from a dynamical approach
• Connecting the Pygmy Dipole Resonance to the neutron skin
• Dipole response in 208Pb within a self-consistent multiphonon approach
• Accessing the Single-Particle Structure of the Pygmy Dipole Resonance in ${}^{208}$Pb
• Clusterized nuclear matter in the (proto-)neutron star crust and the symmetry energy
• Multipole excitations in hot nuclei within the finite temperature quasiparticle random phase approximation framework
• Constraining isovector nuclear interactions with giant resonances within a Bayesian approach
• Interplay between low-lying isoscalar and isovector dipole modes: a comparative analysis between semi-classical and quantum approaches
• Structure and decay of the pygmy dipole resonance in 26Ne
• Anti-analog giant dipole resonances and the neutron skin of nuclei
• Influence of the single-particle structure on the nuclear surface and the neutron skin
• Isoscalar and neutron modes in the E1 spectra of Ni isotopes and the relevance of shell effects and the continuum
• Electric dipole polarizability in neutron-rich Sn isotopes as a probe of nuclear isovector properties
• Nucleus giant resonances from an improved isospin-dependent Boltzmann-Uehling-Uhlenbeck transport approach
• Indirect methods in nuclear astrophysics with relativistic radioactive beams
• Bayesian uncertainty quantification for nuclear matter incompressibility
• Constraining slope parameter of symmetry energy from nuclear structure
• Constraining isovector nuclear interactions with giant dipole resonance and neutron skin in ${}^{208}$Pb from a Bayesian approach
• Low-energy quadrupole states in neutron-rich tin nuclei
• Pigmy resonance in monopole response of neutron-rich Ni isotopes ?
• Nature of low-lying electric dipole resonance excitations in 74Ge
• Bayesian inference of finite-nuclei observables based on the KIDS model
• The decay of quadrupole-octupole $1^{-}$ states in ${}^{40}$Ca and ${}^{140}$Ce
• Neutron-skin thickness of 208Pb from the energy of the anti-analog giant dipole resonance
• Nuclear excitations within microscopic EDF approaches : pairing and temperature effects on the dipole response
• Crossover from skin-mode to proton-neutron-mode in $E1$ excitations of neutron-rich nuclei
• Modeling nuclear weak-interaction processes with relativistic energy density functionals
• Pygmy resonances and symmetry energy
• Probing the neutron skin thickness in collective modes of excitation
• Electric dipole response of sd-shell nuclei within the Configuration-Interaction Shell Model approach
• Dipole response in deformed halo nuclei ${}^{42}\mathrm{Mg}$ and ${}^{44}\mathrm{Mg}$
• Proton pygmy resonances: predictions for N=20 isotones
• Dipole resonances and the nuclear Schiff moment