Nuclear Theory·nucl-th

Tuesday·July 18, 2017

9 papers—3 primary·6 cross-listed

01
[Submitted on 14 Jul 2017]
Symmetry energies for $A = 24$ and $48$ and the USD and KB3 shell model Hamiltonians
A. Kingan · K. Neergård · L. Zamick
Calculations in the sd and pf shells reported some time ago by Satuła\etal\ [Phys.~Lett.~B~407, 103 (1997)] are redone for an extended analysis of the results. As in the original work, we do calculations for one mass number in each shell and consider in each case the sequence of lowest energies for isospins 0, 2, and 4, briefly the symmetry spectrum. Following further the original work we study how this spectrum changes when parts of the two-nucleon interaction are turned off. The variation of its width is explored in detail. A differential combination $ϵ_{W}$ of the three energies was taken in the original work as a measure of the so-called Wigner term in semi-empirical mass formulas, and it was found to decrease drastically when the two-nucleon interaction in the channel of zero isospin is turned off. Our analysis shows that the width of the symmetry spectrum experiences an equally drastic decrease, which can be explained qualitatively in terms of schematic approximations. We therefore suggest that the decrease of $ϵ_{W}$ be seen mainly as a side effect of a narrowing of the symmetry spectrum rather than an independent manifestation of the two-nucleon interaction in the channel of zero isospin.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1707.04608 [pdf]
PRC(2017)·2 citations
02
[Submitted on 16 Jul 2017]
The "Folk Theorem" on Effective Field Theory: How Does It Fare in Nuclear Physics?
Mannque Rho🇫🇷
This is a brief history of what I consider as very important, some of which truly seminal, contributions made by young Korean nuclear theorists, mostly graduate students working on PhD thesis in 1990's and early 2000's, to nuclear effective field theory, nowadays heralded as the first-principle approach to nuclear physics. The theoretical framework employed is an effective field theory anchored on a scale-invariant hidden local symmetric Lagrangian constructed along the line of Weinberg's "Folk Theorem" on effective field theory. The problems addressed are the high-precision calculations on the thermal $n p$ capture, the solar $pp$ fusion process, the solar $h e p$ process -- John Bahcall's challenge to nuclear theorists -- and the quenching of $g_{A}$ in giant Gamow-Teller resonances and the whopping enhancement of first-forbidden beta transitions in astrophysical processes. Extending adventurously the strategy to a wild uncharted domain in which a systematic implementation of the "theorem" is far from obvious, the same effective Lagrangian is applied to the structure of compact stars. A surprising result on the properties of massive stars, totally different from what has been obtained up to day in the literature, is predicted, such as the precocious onset of conformal sound velocity together with the possible emergence of hidden symmetries such as scale symmetry and hidden local symmetry.
Comments:
Invited paper published in JKPS(Journal of the Korean Physical Society)
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1707.04857 [pdf]
J.Korean Phys.Soc.(2017)·2 citations
03
[Submitted on 17 Jul 2017]
Anderson-Bogoliubov phonon in inner crust of neutron stars: Dipole excitation in spherical Wigner-Seitz cell
Tsunenori Inakura · Masayuki Matsuo
Background: The Anderson-Bogoliubov (AB) phonon, called also the superfluid phonon, has attracted attentions since it may influence the thermal conductivity and other properties of inner crust of neutron stars. However, there are limited number of microscopic studies of the AB phonon where the presence of clusters is explicitly taken into account.\\ Purpose: We intend to clarify how the presence of clusters affects the AB phonon in order to obtain microscopic information relevant to the coupling between the AB phonon and the lattice phonon. \\ Methods: The Hartree-Fock-Bogoliubov model and the quasiparticle random-phase approximation formulated in a spherical Wigner-Seitz cell are adopted to describe neutron superfluidity and associated collective excitations. We perform systematic numerical calculations for dipole excitation by varying the neutron chemical potential and the number of protons in a cell. \\ Results:The model predicts systematic emergence of the dipole AB phonon mode, which however exhibits strong suppression of phonon amplitude inside the cluster. We find also that the phonon amplitude around the cluster surface varies as the neutron density. At higher neutron densities the AB phonon mode exhibits behaviour similar to the pygmy dipole resonance in neutron-rich nuclei.\\ Conclusions: The dipole AB phonon mode does not penetrate into the clusters. This suggests that the coupling between the AB phonon and the lattice phonon may be weak.
Comments:
12 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1707.05203 [pdf]
PRC(2017)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE

Symmetry energies for A=24 and 48 and the USD and KB3 shell model Hamiltonians

The "Folk Theorem" on Effective Field Theory: How Does It Fare in Nuclear Physics?

Anderson-Bogoliubov phonon in inner crust of neutron stars: Dipole excitation in spherical Wigner-Seitz cell

Affiliations

Symmetry energies for $A = 24$ and $48$ and the USD and KB3 shell model Hamiltonians