Tomoya Naito 교수

Isospin symmetry breaking (ISB) effects in the charge radius difference $\mathrm{\ensuremath{\Delta}}{R}_{\mathrm{ch}}$ of mirror nuclei are studied using the test example of $^{48}\mathrm{Ca}$ and $^{48}\mathrm{Ni}$. This choice allows for a transparent study of ISB contributions since pairing and deformation effects, commonly required for the study of mirror nuclei, can be neglected in this specific pair. The connection of $\mathrm{\ensuremath{\Delta}}{R}_{\mathrm{ch}}$ with the nuclear equati

Isotope dependences of charge radii, i.e., isotope shifts, calculated by the Skyrme Hartree-Fock, the relativistic mean-field, and the relativistic Hartree-Fock calculations are compared against the experimental data of magic and semimagic nuclei. It is found that the tensor interaction plays a role in reproducing the ``kink'' behavior, irregularity of isotope shifts at the neutron magic number, in the relativistic Hartree-Fock approach. With several Skyrme models, it is found that the kink beha

We perform self-consistent Skyrme Hartree-Fock calculations with the Coulomb exchange functional using the generalized gradient approximation (GGA). It is found that the Perdew-Burke-Ernzerhof GGA (PBE-GGA) Coulomb exchange functional is able to reproduce the exact-Fock energy for nuclei in a wide region of the nuclear chart with one adjustable parameter. The remaining error of the GGA Coulomb exchange energy with respect to the exact-Fock energy dominantly comes from the functional-driven error

We propose a new approach to determine the strength of the charge symmetry breaking (CSB) term in the framework of nuclear density functional theory. It is shown that once ab initio calculations are available including accurate description of isospin symmetry breaking terms in medium and heavy nuclei, the mass difference of mirror nuclei as well as the neutron-skin thickness of doubly-closed-shell nuclei can be used to constrain the strength of the CSB interaction with an uncertainty less than 6

A method is presented to extract the neutron-skin thickness of atomic nuclei from the second and fourth moments of the electric charge distribution. We show that the value of the proton fourth moment must be independently known in order to estimate the neutron-skin thickness experimentally. To overcome this problem, we propose the use of a strong linear correlation among the second and fourth moments of the proton distribution as calculated with several energy density functionals of common use.

We test the Coulomb exchange and correlation energy density functionals of electron systems for atomic nuclei in the local density approximation (LDA) and the generalized gradient approximation (GGA). For the exchange Coulomb energies, it is found that the deviation between the LDA and GGA ranges from around 11% in $^{4}\mathrm{He}$ to around 2.2% in $^{208}\mathrm{Pb}$, by taking the Perdew-Burke-Ernzerhof (PBE) functional as an example of the GGA. For the correlation Coulomb energies, it is sh

Abstract We propose a way to improve energy density functionals (EDFs) in density functional theory based on the combination of the inverse Kohn–Sham method and the density functional perturbation theory. Difference between the known EDF and the exact one is treated as the first-order perturbation. As benchmark calculations, we reproduce the theoretical exchange and correlation functionals in the local density approximation. Systems of noble-gas atoms are used for benchmark calculations, and the

Both the Coulomb interaction and isospin symmetry breaking (ISB) parts of the nuclear interaction break the isospin symmetry in atomic nuclei. Effects of these two kinds of interaction on properties of atomic nuclei, especially the mass difference of mirror nuclei and the neutron-skin thickness of $N=Z$ and $N\ensuremath{\ne}Z$ nuclei, are discussed. It is found that corrections to the Hartree-Fock-Slater approximation for the Coulomb interaction negligibly affect the neutron-skin thickness, whi

The electromagnetic effects of the finite size of the nucleon are implemented self-consistently on top of the Skyrme Hartree-Fock calculation, where the electric form factors of both protons and neutrons are considered. Furthermore, the vacuum polarization and the electromagnetic spin-orbit interaction are taken into account. The self-consistent finite-size effects give a different Coulomb potential from the conventional one and affect the neutrons as well. The contribution of the finite-size ef

We confirm by using the Skyrme Hartree-Fock-Bogoliubov calculation that <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mmultiscripts><a:mi>Pb</a:mi><a:mprescripts/><a:none/><a:mn>164</a:mn></a:mmultiscripts></a:math> is a possible heaviest <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mi>N</b:mi><b:mo>=</b:mo><b:mi>Z</b:mi></b:mrow></b:math> doubly magic nucleus whose lifetime is long enough to be measured on accelerator experiments. We estimate the proton-emission and

We propose a method to calculate wave functions and energies not only of the ground state but also of low-lying excited states using a deep neural network and the unsupervised machine learning technique. For systems composed of identical particles, a simple method to perform symmetrization for bosonic systems and antisymmetrization for fermionic systems is also proposed.

Abstract Atomic nuclei can be spontaneously deformed into non-spherical shapes as many-nucleon systems. We discuss to what extent a similar deformation takes place in many-electron systems. To this end, we employ several many-body methods, such as the unrestricted Hartree–Fock method, post-Hartree–Fock methods, and the density functional theory, to compute the electron density distribution in atoms. We show that the electron density distribution of open-shell atoms is deformed due solely to the

We summarize the recent progress on the determination of the charge symmetry breaking term of nuclear energy density functionals. We point out that the strength of the term determined theoretically is remarkably smaller than that determined phenomenologically, which is still an open question.

Diamagnetic levitation is an appealing technique for levitating objects at room temperature without subjecting the sample to potentially damaging control fields, such as high-intensity laser light or sound pressure. However, owing to the extremely low magnetic susceptibility of diamagnetic materials, except for bismuth and graphite, diamagnetic levitation generally necessitates the use of exceptionally strong magnets, such as those found in world-class high-field facilities. This study simulated