Dipole response in neutron-rich nuclei with new Skyrme interactions

Abstract

We investigate the isoscalar and isovector E1 response of neutron-rich nuclei, within a semi-classical transport model employing effective interactions for the nuclear mean-field. In particular, we adopt the recently introduced SAMi-J Skyrme interactions, whose parameters are specifically tuned to improve the description of spin-isospin properties of nuclei. Our analysis evidences a relevant degree of isoscalar/isovector mixing of the collective excitations developing in neutron-rich systems. Focusing on the low-lying strength emerging in the isovector response, we show that this energy region essentially corresponds to the excitation of isoscalar-like modes, which also contribute to the isovector response owing to their mixed character. Considering effective interactions which mostly differ in the isovector channels, we observe that these mixing effects increase with the slope L of the symmetry energy at saturation density, leading to a larger strength in the low-energy region of the isovector response. This result appears connected to the increase, with L, of the neutron/proton asymmetry at the surface of the considered nuclei, i.e., to the extension of the neutron skin.

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• Extended Skyrme interactions for transport model simulations of heavy-ion collisions
• 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
• Nucleus giant resonances from an improved isospin-dependent Boltzmann-Uehling-Uhlenbeck transport approach
• Nuclear collective dynamics in the lattice Hamiltonian Vlasov method
• Bayesian uncertainty quantification for nuclear matter incompressibility
• Constraining isovector nuclear interactions with giant dipole resonance and neutron skin in ${}^{208}$Pb from a Bayesian approach
• Nuclear collective dynamics in transport model with the lattice Hamiltonian method
• Bayesian inference of finite-nuclei observables based on the KIDS model
• Embedding short-range correlations in relativistic density functionals through quasi-deuterons
• Pre-equilibrium effects in charge-asymmetric low-energy reactions
• Application of an ab-initio-inspired energy density functional to nuclei: impact of the effective mass and the slope of the symmetry energy on bulk and surface properties
• On the spin-isospin decomposition of nuclear symmetry energy