arXiv subjects

Goran Kruzic

Publications and source records attributed to Goran Kruzic.

3 recordsLinked to original sources

arXiv2021

Discerning nuclear pairing properties from magnetic dipole excitation

Pairing correlation of Cooper pair is a fundamental property of multi-fermion interacting systems. For nucleons, two modes of the Cooper-pair coupling may exist, namely of $S_{12}=0$ with $L_{12}=0$ (spin-singlet s-wave) and $S_{12}=1$ with $L_{12}=1$ (spin-triplet p-wave). In nuclear physics, it has been an open question whether the spin-singlet or spin-triplet coupling is dominant, as well as how to measure their role. We investigate a relation between the magnetic-dipole (M1) excitation of nuclei and the pairing modes within the framework of relativistic nuclear energy-density functional (RNEDF). The pairing correlations are taken into account by the relativistic Hartree-Bogoliubov (RHB) model in the ground state, and the relativistic quasi-particle random-phase approximation (RQRPA) is employed to describe M1 transitions. We have shown that M1 excitation properties display a sensitivity on the pairing model involved in the calculations. The systematic evaluation of M1 transitions together with the accurate experimental data enables us to discern the pairing properties in finite nuclei.

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arXiv2020

Role of residual interaction in the relativistic description of M1 excitation

Magnetic dipole (M1) excitation is the leading mode of multi-nucleon excitations induced by the magnetic field, and is a phenomenon of the spin-orbit (SO) splitting and residual interactions involved. In this work, we investigate the effects of the residual interactions on the M1 excitation from a novel perspective, the framework of relativistic nuclear energy-density functional (RNEDF). The relativistic Hartree-Bogoliubov (RHB) model is utilized to determine the nuclear ground state properties, while the relativistic quasi-particle random-phase approximation (RQRPA) is employed for the description of M1-excitation properties. From the analysis of M1 mode in the Ca isotope chain, role of the isovector-pseudovector (IV-PV) residual interaction is discussed. For open-shell nuclei, the pairing correlation also plays a noticeable role in the M1 mode. The experimental data on M1 mode is expected to provide a suitable reference to improve and optimize the theoretical aspects to describe the residual interactions.

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arXiv2019

Relativistic energy-density functional approach to magnetic-dipole excitation and its sum rule

Magnetic-dipole (M1) excitations of $^{18}$O and $^{42}$Ca nuclei are investigated within a relativistic nuclear energy density functional framework. In our last work \cite{2019OP}, these nuclei are found to have unique M1 excitation and its sum rule, because of their characteristic structure: the system consists of the shell-closure core plus two neutrons. For a more systematic investigation of the M1 mode, we have implemented a framework based on the relativistic nuclear energy density functional (RNEDF). For benchmark, we have performed the RNEDF calculations combined with the random-phase approximation (RPA). We evaluate the M1 excitation of $^{18}$O and $^{42}$Ca, whose sum-rule value (SRV) of the M1 transitions can be useful to test the computational implementation \cite{2019OP}. We also apply this RNEDF method to $^{208}$Pb, whose M1 property has been precisely measured \cite{1979Holt,1987Koehler,1988Laszewski,2016Birkhan}. Up to the level of the M1 sum rule, our result is in agreement with the experiments, except the discrepancy related with the quenching factors for $g$ coefficients.

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