Nuclear Theory·nucl-th

Friday·October 16, 2020

10 papers—5 primary·5 cross-listed

01
[Submitted on 15 Oct 2020]
Probing negative-parity states of $^{24}$ Mg probed via proton and alpha inelastic scattering
Yoshiko Kanada-En'yo · Kazuyuki Ogata
[Background:] The band structure of the negative-parity states of $^{24}$ Mg has not yet been clarified. The $K^{π} = 0^{-}$ , $K^{π} = 1^{-}$ , and $K^{π} = 3^{-}$ bands have been suggested, but the assignments have been inconsistent between experiments and theories. [Purpose:] Negative-parity states of $^{24}$ Mg are investigated by microscopic structure and reaction calculations via proton and alpha inelastic scattering to clarify the band assignment for the observed negative-parity spectra. [Method:] The structure of $^{24}$ Mg was calculated using the antisymmetrized molecular dynamics~(AMD). Proton and alpha inelastic reactions were calculated using microscopic coupled-channel (MCC) calculations by folding the Melbourne $g$ -matrix $N N$ interaction with the AMD densities of $^{24}$ Mg. [Results:] The member states of the $K^{π} = 0^{+}$ , $K^{π} = 2^{+}$ , $K^{π} = 0^{-}$ , $K^{π} = 1^{-}$ , and $K^{π} = 3^{-}$ bands of $^{24}$ Mg were obtained through the AMD result. In the MCC+AMD results for proton and alpha elastic and inelastic cross sections, reasonable agreements were obtained with existing data, except in the case of the $4_{1}^{+}$ state. [Conclusions:] The $3^{-}$ state of the $K^{π} = 3^{-}$ band and the $1^{-}$ and $3^{-}$ states of the $K^{π} = 0^{-}$ bands were assigned to the $3_{1}^{-}$ (7.62 MeV), $1_{1}^{-}$ (7.56 MeV), and $3_{2}^{-}$ (8.36 MeV) states, respectively. The present AMD calculation is the first microscopic structure calculation to reproduce the energy ordering of the $K^{π} = 0^{-}$ , $K^{π} = 1^{-}$ , and $K^{π} = 3^{-}$ bands of $^{24}$ Mg.
Comments:
14 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2010.07578 [pdf]
PRC(2021)·10 citations
02
[Submitted on 15 Oct 2020]
Sensitivity of transfer cross sections to the bound-state wave functions
Shubhchintak · P. Descouvemont
We test the sensitivity of transfer reactions to the bound state wave functions within a distorted wave Born approximation formalism. Using supersymmetric transformations, we remove the Pauli-forbidden states from the two-body potentials and generate an equivalent supersymmetric partner. Wave functions from these potentials have the same asymptotics, but they differ in the nuclear interior. This allows us to study the influence of the nuclear interior on transfer cross sections. We apply the calculations to the $^{16}$ O( $d, p$ ) $^{17}$ O and $^{12}$ C( $^{7}$ Li, $t$ ) $^{16}$ O reactions, which are typical examples of nucleon and $α$ transfer, respectively. The spectroscopic factors for $^{17}$ O are decreased by about 30\% when using supersymmetric potentials. For $^{16}$ O, the differences are smaller. However, we show that ambiguities exist in the determination of the spectroscopic factors, due to the choice of the angular range where the fit is performed.
Comments:
Accepted for publication in Physics Letters B
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2010.07617 [pdf]
PLB(2020)·9 citations
03
[Submitted on 15 Oct 2020]
Proton and neutron skins and symmetry energy of mirror nuclei
M.K. Gaidarov · I. Moumene · A.N. Antonov · D.N. Kadrev · P. Sarriguren · E. Moya de Guerra
The neutron skin of nuclei is an important fundamental property, but its accurate measurement faces many challenges. Inspired by charge symmetry of nuclear forces, the neutron skin of a neutron-rich nucleus is related to the difference between the charge radii of the corresponding mirror nuclei. We investigate this relation within the framework of the Hartree-Fock-Bogoliubov method with Skyrme interactions. Predictions for proton skins are also made for several mirror pairs in the middle mass range. For the first time the correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated simultaneously for nuclei and their corresponding mirror partners. As an example, the Ni isotopic chain with mass number $A = 48 - 60$ is considered. These quantities are calculated within the coherent density fluctuation model using Brueckner and Skyrme energy-density functionals for isospin asymmetric nuclear matter with two Skyrme-type effective interactions, SkM* and SLy4. Results are also presented for the symmetry energy as a function of $A$ for a family of mirror pairs from selected chains of nuclei with $Z = 20$ , $N = 14$ , and $N = 50$ . The evolution curves show a similar behavior crossing at the $N = Z$ nucleus in each chain and a smooth growing deviation when $N \neq = Z$ starts. Comparison of our results for the radii and skins with those from the calculations based on high-precision chiral forces is made.
Comments:
17 pages, 7 figures, 2 tables, accepted for publication in Nuclear Physics A
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2010.07652 [pdf]
NPA(2020)·26 citations
04
[Submitted on 15 Oct 2020]
Nuclear collective dynamics in transport model with the lattice Hamiltonian method
Rui Wang · Zhen Zhang · Lie-Wen Chen · Yu-Gang Ma
We review the recent progress on studying the nuclear collective dynamics by solving the Boltzmann-Uehling-Uhlenbeck (BUU) equation with the lattice Hamiltonian method treating the collision term by the full-ensemble stochastic collision approach. This lattice BUU (LBUU) method has recently been developed and implemented in a GPU parallel computing technique, and achieves a rather stable nuclear ground-state evolution and high accuracy in evaluating the nucleon-nucleon (NN) collision term. This new LBUU method has been applied to investigate the nuclear isoscalar giant monopole resonances and isovector giant dipole resonances. While the calculations with the LBUU method without the NN collision term (i.e., the lattice Hamiltonian Vlasov method) describe reasonably the excitation energies of nuclear giant resonances, the full LBUU calculations can well reproduce the width of the giant dipole resonance of $^{208}$ Pb by including a collisional damping from NN scattering. The observed strong correlation between the width of nuclear giant dipole resonance and the NN elastic cross section suggests that the NN elastic scattering plays an important role in nuclear collective dynamics, and the width of nuclear giant dipole resonance provides a good probe of the in-medium NN elastic cross section.
Comments:
27 pages, 7 figures. An invited review to the Research Topic "Advances in Time-Dependent Methods for Nuclear Structure and Dynamics" in Frontiers in Physics
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
2010.07790 [pdf]
Front.in Phys.(2020)·15 citations
05
[Submitted on 15 Oct 2020]
A fully microscopic model of total level density in spherical nuclei
N. Quang Hung · N. Dinh Dang · L. Tan Phuc · N. Ngoc Anh · T. Dong Xuan · T. V. Nhan Hao
A fully microscopic model for the description of nuclear level density (NLD) in spherical nuclei is proposed. The model is derived by combining the partition function of the exact pairing solution plus the independent-particle model at finite temperature (EP+IPM) with that obtained by using the collective vibrational states calculated from the self-consistent Hartree-Fock mean field with MSk3 interaction plus the exact pairing and random-phases approximation (SC-HFEPRPA). Two important factors are taken into account in a fully microscopic way, namely the spin cut-off and vibrational enhancement factors are, respectively, calculated using the statistical thermodynamics and partition function of the SC-HFEPRPA without any fitting parameters. The numerical test for two spherical $^{60}$ Ni and $^{90}$ Zr nuclei shows that the collective vibrational enhancement is mostly dominated by the quadrupole and octupole excitations. This is the first microscopic model confirming such an effect, which was phenomenologically predicted long time ago and widely employed in several NLD models. In addition, the influence of collective vibrational enhancement on nuclear thermodynamic quantities such as excitation energy, specific heat capacity and entropy is also studied by using the proposed model.
Comments:
7 pages, 3 figures, accepted in Phys. Lett. B
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2010.07793 [pdf]
PLB(2020)·10 citations
06
[Submitted on 19 Feb 2015] (cross-list from hep-ph)
Spectra of quark-antiquark bound states via two derived QCD potential
M. S. Ali🇪🇬 · A. M. Yasser🇪🇬
In the current paper, we propose two types of quark-antiquark interactions, which may be tailored to describe various meson sectors. The interactions contain Quantum Chromodynamics (QCD) inspired components, such as the Coulomb-like interaction, the confinement linear potential, and the spin-spin interaction. Our scheme relies on the non-relativistic quark model through the introduction of two derived QCD potential models. The application of the two proposed potentials resulted in spectra for quark-antiquark bound states, which are compared with published experimental data. We found that one of the two potentials is favored over the other in terms of high precision comparisons.
Comments:
12 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); cs.NA (cs.NA); High Energy Physics — Theory (hep-th); math.NA (math.NA); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
1502.06569 [pdf]
3 citations
07
[Submitted on 15 Oct 2020] (cross-list from cond-mat.quant-gas)
Rotating quantum turbulence in the unitary Fermi gas
Khalid Hossain🇺🇸 · Konrad Kobuszewski🇵🇱 · Michael McNeil Forbes🇺🇸 · Piotr Magierski🇺🇸 · Kazuyuki Sekizawa🇯🇵 · Gabriel Wlazłowski🇺🇸
Quantized vortices carry the angular momentum in rotating superfluids, and are key to the phenomenon of quantum turbulence. Advances in ultra-cold atom technology enable quantum turbulence to be studied in regimes with both experimental and theoretical control, unlike the original contexts of superfluid helium experiments. While much work has been performed with bosonic systems, detailed studies of fermionic quantum turbulence are nascent, despite wide applicability to other contexts such as rotating neutron stars. In this paper, we present the first large-scale study of quantum turbulence in rotating fermionic superfluids using an accurate orbital based time-dependent density functional theory (DFT) called the superfluid local density approximation (SLDA). We identify two different modes of turbulent decay in the dynamical equilibration of a rotating fermionic superfluid, and contrast these results with a computationally simpler orbital-free DFT, which we find can qualitatively reproduce these decay mechanisms if dissipation is explicitly included. These results demonstrate that one-body dissipation mechanisms intrinsic to fermionic superfluids play a key role differentiating fermionic from bosonic turbulence, but also suggest that simpler orbital-free theories may be corrected so that these more efficient techniques can be used to model extended physical systems such as neutron superfluids in neutron stars.
Comments:
13 pages, 8 figures. Accompanying movies can be found at http://wlazlowski.fizyka.pw.edu.pl/supplement/sm-rotating-turbulence/
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2010.07464 [pdf]
PRA(2022)·17 citations
08
[Submitted on 15 Oct 2020] (cross-list from hep-ph)
QCD and the Strange Baryon Spectrum
Tetsuo Hyodo🇯🇵 · Masayuki Niiyama🇯🇵
The strange quark plays a unique role in QCD, reflecting its intermediate mass between the light and heavy quarks. In recent years, remarkable progress has been made in the spectroscopy of baryons with strangeness. Many new features of the strange baryon spectrum have been revealed by accurate experimental data with novel techniques, as well as systematic developments of theoretical framework to describe hadron resonances. The basic properties of strange baryons, namely, the pole positions, spin and parity, and decay branching ratios, are being determined accurately. As a consequence, the Particle Data Group have added new entries in the particle listings, such as the $Λ (1380)$ and the $Ω (2012)$ . The developments of the spectroscopy stimulate intensive discussion on the exotic internal structure of strange baryons beyond the ordinary three-quark configuration. In this review, we introduce the basics of QCD, the scattering theory, and the exotic internal structure of hadrons, emphasizing the importance of the pole positions of the scattering amplitude for the characterization of hadron resonances. We then summarize the current status of selected strange baryon resonances; $Λ (1405)$ , $Λ (1670)$ , $Ξ (1620)$ , $Ξ (1690)$ , and $Ω (2012)$ , from theoretical and experimental viewpoints.
Comments:
64 pages, 21 figures, to appear in Prog. Part. Nucl. Phys
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2010.07592 [pdf]
PPNP(2021)·86 citations
09
[Submitted on 15 Oct 2020] (cross-list from hep-ph)
Setting the string shoving picture in a new frame
Christian Bierlich🇸🇪 · Smita Chakraborty🇸🇪 · Gösta Gustafson🇸🇪 · Leif Lönnblad🇸🇪
Based on the recent success of the \angantyr model in describing multiplicity distributions of the hadronic final state in high energy heavy ion collisions, we investigate how far one can go with a such a string-based scenario to describe also flow effects measured in such collisions. For this purpose we improve our previous so-called \textit{shoving} model, where strings that are close in space--time tend to repel each other in a way that could generate anisotropic flow, and we find that this model can indeed generate such flows in Å\ collisions. The flow generated is not quite enough to reproduce measurements, but we identify some short-comings in the presented implementation of the model that, when fixed, could plausibly give a more realistic amount of flow.
Comments:
42 pages, 34 figures, submission to JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2010.07595 [pdf]
JHEP(2021)·59 citations
10
[Submitted on 15 Oct 2020] (cross-list from physics.chem-ph)
Hydrogen molecule spectrum by many-body GW and Bethe-Salpeter equation
Jing Li🇫🇷 · Valerio Olevano🇫🇷
We check the ab initio GW approximation and Bethe-Salpeter equation (BSE) many-body methodology against the exact solution benchmark of the hydrogen molecule H $_{2}$ ground state and excitation spectrum, and in comparison with the configuration interaction (CI) and time-dependent Hartree-Fock methods. The comparison is made on all the states we could unambiguously identify from the excitonic wave functions' symmetry. At the equilibrium distance $R = 1.4 a_{0}$ , the GW+BSE energy levels are in good agreement with the exact results, with an accuracy of 0.1~0.2 eV. GW+BSE potential-energy curves are also in good agreement with the CI and the exact result up to $2.3 a_{0}$ . The solution no longer exists beyond $3.0 a_{0}$ for triplets ( $4.3 a_{0}$ for singlets) due to instability of the ground state. We tried to improve the GW reference ground state by a renormalized random-phase approximation (r-RPA), but this did not solve the problem.
Comments:
6 pages 4 figures, 2 table
Subjects:
physics.chem-ph (physics.chem-ph); cond-mat.other (cond-mat.other); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
2010.07780 [pdf]
PRA(2021)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE