Nuclear Theory·nucl-th

Tuesday·August 9, 2022

16 papers—6 primary·10 cross-listed

01
Optimized Dirac Woods-Saxon basis for covariant density functional theory
K. Y. Zhang · C. Pan · S. Q. Zhang
The Woods-Saxon basis has achieved great success in both nonrelativistic and covariant density functional theories in recent years. Due to its nonanalytical nature, however, applications of the Woods-Saxon basis are numerically complicated and computationally time consuming. In this paper, based on the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc), we check in detail the convergence with respect to the basis space in the Dirac sea. An optimized Dirac Woods-Saxon basis is proposed, whose corresponding potential is close to the nuclear mean field. It is shown that the basis space of the optimized Dirac Woods-Saxon basis required for convergence is substantially reduced compared with the original one. In particular, it does not need to contain the bases from continuum in the Dirac sea. The application of the optimized Woods-Saxon basis would greatly reduce computing resource for large-scale density functional calculations.
nucl-thPRC(2022)·44 citations
02
An effective and efficient algorithm for the Wigner rotation matrix at high angular momenta
Bin-Lei Wang · Fan Gao · Long-Jun Wang · Yang Sun
The Wigner rotation matrix ( $d$ -function), which appears as a part of the angular-momentum-projection operator, plays a crucial role in modern nuclear-structure models. However, it is a long-standing problem that its numerical evaluation suffers from serious errors and instability, which hinders precise calculations for nuclear high-spin states. Recently, Tajima [Phys. Rev. C 91, 014320 (2015)] has made a significant step toward solving the problem by suggesting the high-precision Fourier method, which however relies on formula-manipulation softwares. In this paper we propose an effective and efficient algorithm for the Wigner $d$ function based on the Jacobi polynomials. We compare our method with the conventional Wigner method and the Tajima Fourier method through some testing calculations, and demonstrate that our algorithm can always give stable results with similar high-precision as the Fourier method, and in some cases (for special sets of $j, m, k$ and $θ$ ) ours are even more accurate. Moreover, our method is self-contained and less memory consuming. A related testing code and subroutines are provided as Supplemental Material in the present paper.
nucl-thcond-mat.str-elmath-phmath.MP+2PRC(2022)·13 citations
03
Bubble nuclei: single-particle versus Coulomb interaction effects
U. C.Perera · A. V. Afanasjev
The detailed investigation of microscopic mechanisms leading to the formation of bubble structures in the nuclei has been performed in the framework of covariant density functional theory. The main emphasis of this study is on the role of single-particle degrees of freedom and Coulomb interaction. In general, the formation of bubbles lowers the Coulomb energy. However, in nuclei this trend is counteracted by the quantum nature of the single-particle states: only specific single-particle states with specific density profiles can be occupied with increasing proton and neutron numbers. A significant role of central classically forbidden region at the bottom of the wine bottle potentials in the formation of nuclear bubbles (via primarily the reduction of the densities of the $s$ states at $r = 0$ ) has been revealed for the first time. Their formation also depends on the availability of low- $l$ single-particle states for occupation since single-particle densities represent the basic building blocks of total densities. Nucleonic potentials disfavor the occupation of such states in hyperheavy nuclei and this contributes to the formation of bubbles in such nuclei. Additivity rule for densities has been proposed for the first time. It was shown that the differences in the densities of bubble and flat density nuclei follow this rule in the $A \approx 40$ mass region and in superheavy nuclei with comparable accuracy. This strongly suggests the same mechanism of the formation of central depression in bubble nuclei of these two mass regions. Nuclear saturation mechanisms and self-consistency effects also affect the formation of bubble structures. The detailed analysis of different aspects of bubble physics strongly suggests that the formation of bubble structures in superheavy nuclei is dominated by single-particle effects.
nucl-thPRC(2022)·12 citations
04
Weinberg operator contribution to the CP-odd nuclear force in the quark model
Nodoka Yamanaka🇯🇵 · Makoto Oka🇯🇵
The contribution of the CP violating three-gluon interaction, proposed by Weinberg, to the short-range CP-odd nuclear force is evaluated in the nonrelativistic quark model. We first show that the naive leading contribution generated by the quark exchange process vanishes at sufficiently short distance within the resonating group method, by considering the one-loop level gluon exchange CP-odd interquark potential induced by the Weinberg operator with massive quarks and gluons. We then estimate the true leading contribution by evaluating the gluonic correction to the CP-odd interquark potential in the closure approximation. It is found that the resulting irreducible CP-odd nuclear force is comparable to that generated by the chiral rotation of the CP-even short-range nuclear force, where the CP-odd mass calculated with QCD sum rules is used as input. The explicit calculation of the electric dipole moment (EDM) of the $^{3}$ He nucleus yields $d_{^{3} He}^{(irr)} (w) = - 1.5 w e$ MeV. The total $^{3}$ He EDM, accounting for the intrinsic nucleon EDM, the pion-exchange and the short-range CP-odd nuclear force, is $d_{^{3} He}^{(tot)} (w) = 2 0_{- 11}^{+ 14} w e$ MeV, with the dominant effect coming from the intrinsic nucleon EDM.
nucl-thhep-exhep-phnucl-exPRD(2022)·7 citations
05
Reconciling Multi-messenger Constraints with Chiral Symmetry Restoration
Michał Marczenko🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱
We consider the parity doublet model for nucleonic and delta matter to investigate the structure of neutron stars. We show that it is possible to reconcile the multi-messenger astronomy constraints within a purely hadronic equation of state (EOS), which accounts for the self-consistent treatment of the chiral symmetry restoration in the baryonic sector. We demonstrate that the characteristics of the EOS required by the astrophysical constraints do not necessarily imply the existence of a hadron-quark phase transition in the stellar core.
nucl-thastro-ph.HEActa Phys.Polon.Supp.(2023)·1 citation
06
Precision calculation of the recoil--finite-size correction for the hyperfine splitting in muonic and electronic hydrogen
Aldo Antognini🇨🇭 · Yong-Hui Lin🇩🇪 · Ulf-G. Meißner🇩🇪
We present a high-precision calculation of the recoil--finite-size correction to the hyperfine splitting (HFS) in muonic and electronic hydrogen based on nucleon electromagnetic form factors obtained from dispersion theory. This will help guide the upcoming searches of the HFS transition in muonic hydrogen, and will allow a precise determination of the polarizability and Zemach radius contributions when this transition is found.
nucl-thhep-phphysics.atom-phPLB(2022)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE

Optimized Dirac Woods-Saxon basis for covariant density functional theory

An effective and efficient algorithm for the Wigner rotation matrix at high angular momenta

Bubble nuclei: single-particle versus Coulomb interaction effects

Weinberg operator contribution to the CP-odd nuclear force in the quark model

Reconciling Multi-messenger Constraints with Chiral Symmetry Restoration

Precision calculation of the recoil--finite-size correction for the hyperfine splitting in muonic and electronic hydrogen

Affiliations