Y. F. Niu

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

The self-consistent random-phase approximation, based on the framework of relativistic energy density functionals, is employed in the study of isovect

Gamow-Teller response within Skyrme random-phase approximation plus particle-vibration coupling

Although many random-phase approximation (RPA) calculations of the Gamow-Teller (GT) response exist, this is not the case for calculations going beyond the mean-field approximation. We apply a consistent model, that includes the coupling of the GT resonance to low-lying vibrations, to nuclei of the fp shell. Among other motivations, our goal is to see if the particle-vibration coupling can redistribute the low-lying GT(+) strength that is relevant for electron-capture processes in core-collapse supernova. We conclude that the lowering and fragmentation of that strength are consistent with the experimental findings and validate our model. However, the particle-vibration coupling cannot account for the quenching of the total value of the low-lying strength.

Stellar electron-capture rates calculated with the finite-temperature relativistic random-phase approximation

We introduce a self-consistent microscopic theoretical framework for modeling the process of electron capture on nuclei in stellar environment, based on relativistic energy density functionals. The finite-temperature relativistic mean-field model is used to calculate the single-nucleon basis and the occupation factors in a target nucleus, and Jπ=0±, 1±, and 2± charge- exchange transitions are described by the self-consistent finite- temperature relativistic random-phase approximation. Cross sections and rates are calculated for electron capture on 54, 56Fe and 76, 78Ge in stellar environment, and results compared with predictions of similar and complementary model calculations.

Particle-Vibration Coupling Effect on the beta Decay of Magic Nuclei

Nuclear β decay in magic nuclei is investigated, taking into account the coupling between particles and collective vibrations, on top of self-consistent random phase approximation calculations based on Skyrme density functionals. The low-lying Gamow-Teller strength is shifted downwards and at times becomes fragmented; as a consequence, the β-decay half-lives are reduced due to the increase of the phase space available for the decay. In some cases, this leads to a very good agreement between theoretical and experimental lifetimes: this happens, in particular, in the case of the Skyrme force SkM* that can also reproduce the line shape of the high-energy Gamow-Teller resonance as was previously shown.

Gamow-Teller response and its spreading mechanism in doubly magic nuclei

The scope of the paper is to apply a state-of-the-art beyond mean-field model to the description of the Gamow-Teller response in atomic nuclei. This topic recently attracted considerable renewed interest, due, in particular, to the possibility of performing experiments in unstable nuclei. We study the cases of

Pairing transitions in finite-temperature relativistic Hartree-Bogoliubov theory

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Self-consistent relativistic quasiparticle random-phase approximation and its applications to charge-exchange excitations

Ca,

Nuclear beta(+)/EC decays in covariant density functional theory and the impact of isoscalar proton-neutron pairing

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Low-energy monopole and dipole response in nuclei at finite temperature

Ni,

Nuclear effective charge factor originating from covariant density functional theory

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