Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session LG: Nuclear Theory 3 |
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Chair: Hitoshi Nakada, Chiba University Room: Hilton King's 3 |
Saturday, October 27, 2018 9:00AM - 9:15AM |
LG.00001: SeaLL1: A Minimal Nuclear Energy Density Functional Michael McNeil Forbes, Aurel Bulgac, Shi Jin, Nicolas Schunck, Rodrigo Navarro Perez In this talk I shall describe our recently proposed SeaLL1 nuclear energy density functional (NEDF). SeaLL1 is systematically constructed to contain the minimal number of phenomenological parameters (7), each related to a specific nuclear property. Despite this minimal nature, it provides remarkable global mass and radius fits, comparable or better than with current state-of-the-art NEDFs that contain often many more parameters. Despite only being fit to static phenomena, SeaLL1 displays very reasonable dynamical properties such as fission barriers, suggesting a new paradigm for improving nuclear DFT calculations. |
Saturday, October 27, 2018 9:15AM - 9:30AM |
LG.00002: Coulomb Energy Density Functionals for Nuclear Systems Tomoya Naito, Ryosuke Akashi, Gianluca Col\`{o}, Haozhao Liang, Xavier Roca-Maza The Coulomb exchange and correlation contributions to the energy density functionals were tested in the context of atomic nuclei \footnote{T. Naito, R. Akashi, and H. Liang. PRC~97,~044319~(2018).}. Both the local density approximation (LDA) and generalized gradient approximation (GGA) functionals were investigated. We employed the experimental nuclear charge density as input. The GGA exchange functionals of electron systems can be applied with practical accuracy to atomic nuclei. In contrast, the correlation functionals of electron systems are not applicable for atomic nuclei. Self-consistent calculation of the GGA exchange functional was also tested \footnote{T. Naito, X. Roca-Maza, G. Col\`{o}, and H. Liang. In Progress.}. In most cases, the GGA exchange functional represents the exact-Fock Coulomb energy while one of the GGA-functional coefficients is changed. This fact is remarkable since the numerical cost of GGA is $O(N^3)$, whereas that cost of exact Hartree-Fock approximation is $O(N^4)$ for the self-consistent calculations. |
Saturday, October 27, 2018 9:30AM - 9:45AM |
LG.00003: Dynamical properties of the SeaLL1 Nuclear Energy Density Functional Ryan Corbin, Michael Forbes Time dependent density functional theory (TDDFT) is currently the preferred method for tackling calculations of dynamic nuclear properties, given a properly formulated energy functional. However, exact calculations in this framework are computationally expensive. In this talk I consider the less expensive orbital free formulation of the recently proposed SeaLL1 nuclear energy density functional (NEDF), a minimal parameter functional. The dynamical properties of this functional will be discussed, such as the giant dipole resonance (GDR); particular attention will be paid to the effects of the entrainment term. |
Saturday, October 27, 2018 9:45AM - 10:00AM |
LG.00004: Collective coordinate for pairing dynamics and requantization of TDHFB Takashi Nakatsukasa, Fang Ni The pairing is one of the most important correlations in nuclei. Pairing rotation and vibration are well-known collective motions associated with pair dynamics. Time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory is able to describe such pair dynamics. However, although the TDHFB provides an initial-value problem in real time, it is not easy to calculate energy eigenstates. In order to obtain such quantal information from TDHFB, we study suitable collective coordinates and the quantization method for pair models. We start from a simple two-level pair model to investigate the feasibility and the accuracy of the method. We have found that, since the collectivity associated with pairing motion are relatively weak, a conventional canonical quantization method is not accurate enough in most cases. It is important to construct microscopic wave functions of energy eigenstates. We use the stationary-phase approximation of the path integral for this purpose [1]. In this presentation, we will show application of the method to extended multi-level cases and demonstrate the usefulness of the method. [1] F. Ni and T. Nakatsukasa, Phys. Rev. C 97, 044310 (2018). |
Saturday, October 27, 2018 10:00AM - 10:15AM |
LG.00005: Excitation modes and collective inertia in triaxial superfluid nuclei Kouhei Washiyama, Takashi Nakatsukasa Phenomena of shape fluctuation and shape mixing in nuclei appear in transitional regions. For these phenomena, our goal is to construct the collective Hamiltonian by the constrained Hartree-Fock-Bogoliubov (CHFB) for the collective potential and local quasiparticle random phase approximation (LQRPA) for the collective inertia with Skyrme energy density functionals. With the help of the finite amplitude method (FAM)[1] that efficiently obtains response functions with less computational cost than that of QRPA, we constructed Skyrme FAM in three-dimensional coordinate[2]. Then, we extended our 3D FAM to calculating rotational moment of inertia at triaxially-constrained HFB states[3]. In this contribution, we will present those results and discuss the phenomena of shape fluctuations in transitional nuclei. [1] T. Nakatsukasa, T. Inakura, and K. Yabana, Phys.Rev.C 76, 024318 (2007) [2] K. Washiyama and T. Nakatsukasa, Phys.Rev.C 96, 041304(R) (2017) [3] K. Washiyama and T. Nakatsukasa, arXiv:1803.06828 |
Saturday, October 27, 2018 10:15AM - 10:30AM |
LG.00006: A Quantum Mechanical Treatment of Nuclear Collective Motion Nouredine Zettili In this work, we deal with a quantum mechanical treatment of nuclear collective motion. To carry out this study, we invoke the nuclear Born--Oppenheirmer (NBO) method. We focus in particular on a quantum mechanical approach to nuclear rotations. As an illustration, we deal with non-spherical, permanently deformed nuclei; in particular, we study nuclei that are axially-symmetric and even, but with non-closed shells. Moreover, we look at a quantum mechanical derivation of formal expressions for the energy and for the moment of inertia. Using a mean-field approximation to describe the intrinsic structure, we show that the NBO formalism yields the Thouless-Valantin formula for the moment of inertia. We then show that this moment of inertia increases with angular momentum, in agreement with experimental data. We show that the NBO formalism is well equipped to describe low-lying as well as high-lying rotational states. Finally, we establish a connection between the NBO method and the self-consistent Cranking (SCC) model, which is known to successfully reproduce vast amounts of experimental data ranging from low-lying rotational states to high angular momentum states. |
Saturday, October 27, 2018 10:30AM - 10:45AM |
LG.00007: Superfluid phase transition and effects of pairing fluctuations in neutron star matter at subnuclear densities Hiroyuki Tajima, Tetsuo Hatsuda, Pieter van Wyk, Yoji Ohashi We investigate the s-wave superfluidity in asymmetric nuclear matter in the inner crust and the outer core of the neutron stars. Within the framework of diagrammatic strong coupling theory, which can successfully describe the Bardeen-Cooper-Schrieffer-Bose-Einstein-condensation (BCS-BEC) crossover realized in ultracold Fermi atomic gases, we clarify effects of strong pairing fluctuations on the critical temperature of the superfluid phase transition under the presence of the effective-range correction and the short-range repulsion for the neutron-neutron interaction. Furthermore, considering a finite proton fraction, we show the effects of the strong neutron-proton interaction on the spin-triplet deuteron condensation, as well as on the spin-singlet dineutron and diproton condensations. Our microscopic study on the superfluidity in neutron star matter is important for understanding the astrophysical observations of the thermal properties of neutron stars. |
Saturday, October 27, 2018 10:45AM - 11:00AM |
LG.00008: Spin Polarized Phases in Quark Matter: Interplay between Axial-vector and Tensor Mean Fields Tomoyuki Maruyama, Eiji Nakano, Kota Kota Yanase, Naotaka Yoshinaga The spontaneous spin polarization of strongly interacting matter due to axial-vector and tensor |
Saturday, October 27, 2018 11:00AM - 11:15AM |
LG.00009: Hohenberg-Kohn-theorem-inspired functional renormalization-group analysis of ground and excited states of a one-dimensional nuclear matter Takeru Yokota, Kenichi Yoshida, Teiji Kunihiro We present the first successful functional renormalization group(FRG)-aided density-functional (DFT) calculation of the equation of state (EOS) and the density-density spectral function of an infinite nuclear matter (NM) in (1+1) dimensions composed of spinless nucleons. The resultant EOS of the NM coincides with that obtained by the Monte-Carlo method within a few percent for the available range of density. We also reproduce a notable feature of the density density spectral function of the non-linear Tomonaga-Luttinger liquid: The spectral function has singularities at the edge of its support at the lower-energy side. Our result demonstrates that the FRG-aided DFT can be as powerful as any other methods in quantum many-body theory. |
Saturday, October 27, 2018 11:15AM - 11:30AM |
LG.00010: Large-scale shell-model calculations on nuclei around mass 210 Naotaka Yoshinaga, Kota Yanase, Koji Higashiyama, Eri Teruya Large-scale shell-model calculations are performed for heavy nuclei with Z 82 around ^{208}Pb. One feature for nuclei in this mass region is the existence of a lot of low-lying negative parity states. The low-lying 3^{- }states which are made by the core excitations are found in several nuclei. In contrast, it is known that the several 3^{-} states are lowered by the collective octupole correlation among valence nucleons. However, the theoretical investigations in this region are not enough so that the microscopic structures of these nuclei have not been clarified yet. In this study, shell-model calculations are performed for even-even, odd-mass, and doubly-odd nuclei of Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn, and Fr isotopes assuming ^{208}Pb as a doubly magic core. As for a phenomenological interaction, one set of the two-body interaction strengths, which consists of the multipole-paring interactions including the monopole pairing and quadrupole-quadrupole interactions, is employed for all the nuclei considered. Energy spectra and electromagnetic properties are calculated and compared with the experimental data. In addition, several typical isomers are investigated. Part of this work is presented in Ref. [1]. [1] E. Teruya, K. Higashiyama, and N. Yoshinaga, Phys. Rev. C 93, 064327 (2016). |
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