Nuclear Theory·nucl-th

Monday·November 29, 2021

21 papers—7 primary·14 cross-listed

01
Trends of Neutron Skins and Radii of Mirror Nuclei from First Principles
S. J. Novario · D. Lonardoni · S. Gandolfi · G. Hagen
The neutron skin of atomic nuclei impacts the structure of neutron-rich nuclei, the equation of state of nucleonic matter, and the size of neutron stars. Here we predict the neutron skin of selected light- and medium-mass nuclei using coupled-cluster theory and the auxiliary field diffusion Monte Carlo method with two- and three-nucleon forces from chiral effective field theory. We find a linear correlation between the neutron skin and the isospin asymmetry in agreement with the liquid-drop model and compare with data. We also extract the linear relationship that describes the difference between neutron and proton radii of mirror nuclei and quantify the effect of charge symmetry breaking terms in the nuclear Hamiltonian. Our results for the mirror-difference charge radii and binding energies per nucleon agree with existing data.
nucl-thPRL(2023)·69 citations
02
Ab initio calculation of muon capture on $^{24}$ Mg
L. Jokiniemi🇪🇸 · T. Miyagi🇨🇦 · S. R. Stroberg🇺🇸 · J. D. Holt🇨🇦 · J. Kotila🇫🇮 · J. Suhonen🇫🇮
In this work we study ordinary muon capture (OMC) on $^{24}$ Mg from a first principles perspective. Starting from a particular two- and three-nucleon interaction derived from chiral effective field theory, we use the valence-space in-medium similarity renormalization group (VS-IMSRG) framework to construct effective Hamiltonians and muon-capture operators which nonperturbatively account for many-body physics outside the valence space. The obtained nuclear matrix elements are compared against those from the phenomenological shell model. The impact of including the correlations from the nuclear shell model (NSM) as well as including the induced two-body part is studied in detail. Furthermore, the effects of realistic bound-muon wave function on the operators is studied. Finally, predictions for capture rates to the lowest excited states in $^{24}$ Na are given and compared with available data. It is found that the spectroscopic properties of $^{24}$ Mg and its OMC daughter $^{24}$ Na are fairly well described by both the NSM and VS-IMSRG, and that the effect of the hadronic two-body currents significantly reduces the OMC rates. Both models have some difficulties in matching the measured OMC rates, especially for the $2^{+}$ final states. This calls for further studies in other light nuclei with available OMC data.
nucl-thPRC(2023)·23 citations
03
Inertial energy dissipation in nuclear dynamics
Yoritaka Iwata · Takashi Nishikawa
We present the TDDFT+Langevin model that incorporates microscopic time-dependent density function theory (TDDFT) with macroscopic Langevin model. By extracting the energy-dependent dissipation effect from the TDDFT dynamics, quantum effects are introduced to the Langevin-type stochastic fission analysis. In this paper, by means of Skyrme nuclear effective interactions, the energy-dependent friction coefficients to be used in Langevin calculations are provided individually for 25 fission nuclei chosen from uranium, plutonium, curium, californium, and fermium isotopes. The validity of the energy-dependent friction coefficients are confirmed by comparing to the existing experimental fission fragment yields. In conclusion, depending on the energy, the transition of energy dissipation mechanism from conventional viscous energy dissipation to inertial energy dissipation is shown.
nucl-thnucl-exPRC(2022)·3 citations
04
Formation of a supergiant quantum vortex in a relativistic Bose-Einstein condensate driven by rotation and a parallel magnetic field
Tao Guo🇨🇳 · Jianing Li🇨🇳 · Chengfu Mu🇨🇳 · Lianyi He🇨🇳
Analysis based on the energy spectrum of noninteracting bosons shows that, under the circumstance of parallel rotation and magnetic field, charged bosons form a Bose-Einstein condensate because of the lift of the Landau level degeneracy by rotation [\textcolor{blue}{Y. Liu and I. Zahed, Phys. Rev. Lett. {\bf120}, 032001 (2018)}]. In this work, we study the interaction effect on the ground state of this Bose-Einstein condensate of charged bosons from the viewpoint of spontaneous symmetry breaking. We employ a minimal model for charged bosons with repulsive self-interaction. We find that the ground state of such a Bose-Einstein condensate is a supergiant quantum vortex, i.e., a quantized vortex with a large circulation. The size of the vortex is as large as the system size. The low-energy dispersion of the excitation spectra exhibits quadratic behavior, which is an anisotropic realization of the type-II Goldstone boson. Our study may give some implications to off-central relativistic heavy ion collisions, where large vorticity and magnetic fields can be generated.
nucl-thcond-mat.quant-gascond-mat.supr-conhep-phPRD(2022)·13 citations
05
Effects of rotation and valence nucleons in molecular-like $α$ -chain nuclei
D. D. Zhang · Z. X. Ren · P. W. Zhao · D. Vretenar · T. Nikšić · J. Meng
Effects of rotation and valence nucleons in molecular-like linear $α$ -chain nuclei are analyzed using a three-dimensional lattice cranking model based on covariant density functional theory. The structure of $^{16}$ C and $^{16}$ Ne is investigated as a function of rotational frequency. The valence nucleons, with respect to the 3 $α$ linear chain core of $^{12}$ C, at low frequency occupy the $π$ molecular orbital. With increasing rotational frequency these nucleons transition from the $π$ orbital to the $σ$ molecular orbital, thus stabilizing the 3 $α$ linear chain structure. It is predicted that the valence protons in $^{16}$ Ne change occupation from the $π$ to the $σ$ molecular orbital at $ℏ ω \approx 1.3$ MeV, a lower rotational frequency compared to $ℏ ω \approx 1.7$ MeV for the valence neutrons in $^{16}$ C. The same effects of valence protons are found in $^{20}$ Mg, compared to the four valence neutrons in $^{20}$ O. The model is also used to examine the effect of alignment of valence nucleons on the relative positions and size of the three $α$ -clusters in $^{16}$ C and $^{16}$ Ne.
nucl-thPRC(2022)·18 citations
06
Collectivity of $J / ψ$ Mesons in Heavy-Ion Collisions
Min He🇨🇳 · Biaogang Wu🇺🇸 · Ralf Rapp🇺🇸
The production of $J / ψ$ mesons in heavy-ion collisions at the Large Hadron Collider is believed to be dominated by the recombination of charm and anti-charm quarks in a hot QCD medium. However, measurements of the elliptic flow ( $v_{2}$ ) of $J / ψ$ mesons in these reactions are not well described by existing calculations of $J / ψ$ recombination for transverse momenta $p_{T} \geq$ 4 GeV. Here, we revisit these calculations in two main aspects. By employing the resonance recombination model, we implement distribution functions of charm quarks transported through the quark-gluon plasma using state-of-the-art Langevin simulations, and we account for the space-momentum correlations of the diffusing charm and anti-charm quarks in the hydrodynamically expanding fireball. These improvements extend the relevance of the recombination processes to substantially larger momenta than before. In addition, we revisit the suppression of the primordially produced $J / ψ$ mesons by propagating them through the same hydrodynamic medium, leading to a marked increase of the $v_{2}$ of this component over previous estimates. Combining these developments into a calculation of the $p_{T}$ -dependent nuclear modification factor and $v_{2}$ of inclusive $J / ψ$ production in semi-central Pb-Pb collisions at the LHC, we find a good description of the experimental results by the ALICE collaboration. Our results thus resolve the above-mentioned $v_{2}$ puzzle and imply the relevance of recombination processes for $p_{T}$ 's of up to $\sim$ 8 GeV.
nucl-thhep-phnucl-exPRL(2022)·53 citations
07
Radial overlap correction to superallowed $0^{+} \to 0^{+}$ nuclear $β$ decays using the shell model with Hartree-Fock radial wave functions
Latsamy Xayavong🇱🇦 · Nadezda Smirnova🇫🇷
The radial overlap correction, $δ_{R O}$ is re-examined for 30 superallowed $β$ decays using the shell model with Hartree-Fock (HF) radial wave functions. Our calculation is based on the Skyrme interaction including Coulomb, Charge-Symmetry-Breaking (CSB) and Charge-Independence-Breaking (CIB) terms. The corrections due to the gradient of charge density, vacuum polarization, Coulomb spin-orbit and finite size of nucleons are also considered. To avoid the spurious isospin mixing, the local equivalent potential is constructed from the solution of a HF calculation for the $Z = N$ nucleus without charge-dependent forces. The obtained mean field is solved non-iteratively for the parent and daughter nuclei. It turns out that the CIB term has no significant impact on $δ_{R O}$ . On the other hand, the CSB term makes $δ_{R O}$ increasing between 10 and 30%. The gradient density leads to a further increase of $δ_{R O}$ between 2 and 14%, while other electromagnetic corrections are negligible. The effect of the suppression of isospin spuriosity is somewhat complicated. In general, it produces a larger $δ_{R O}$ value, however there are few cases for which $δ_{R O}$ is mostly unaffected or even reduced, especially the light even-even emitters. All these improvements partly explain the long-standing discrepancy between the correction values obtained with Woods-Saxon (WS) and HF radial wave functions. Nevertheless, the remaining discrepancy is still significant, except for the emitters with $A \leq 26$ . In addition, the staggering presented on the results obtained with the WS potential are not well reproduced by our calculations. This subsequently leads to a large difference in the predicted mirror $f t$ ratios. These problems might relate to the errors of the calculated radii as well as correlation in the data used for constraining the asymptotic radial wave functions.
nucl-thPRC(2022)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE

Trends of Neutron Skins and Radii of Mirror Nuclei from First Principles

Ab initio calculation of muon capture on 24Mg

Inertial energy dissipation in nuclear dynamics

Formation of a supergiant quantum vortex in a relativistic Bose-Einstein condensate driven by rotation and a parallel magnetic field

Effects of rotation and valence nucleons in molecular-like α-chain nuclei

Collectivity of J/ψ Mesons in Heavy-Ion Collisions

Radial overlap correction to superallowed 0+→0+ nuclear β decays using the shell model with Hartree-Fock radial wave functions

Affiliations

Ab initio calculation of muon capture on $^{24}$ Mg

Effects of rotation and valence nucleons in molecular-like $α$ -chain nuclei

Collectivity of $J / ψ$ Mesons in Heavy-Ion Collisions

Radial overlap correction to superallowed $0^{+} \to 0^{+}$ nuclear $β$ decays using the shell model with Hartree-Fock radial wave functions