Nuclear Theory·nucl-th

Tuesday·October 23, 2018

9 papers—8 primary·1 cross-listed

01
[Submitted on 20 Oct 2018]
Ab initio Rayleigh-Schrödinger perturbation calculation including three-body force
B. S. Hu🇨🇳 · T. Li🇨🇳 · F. R. Xu🇨🇳
We first derive the Rayleigh-Schrödinger many-body perturbation theory up to third order (RSPT3) for Hamiltonians with three-body interaction. The structure of closed-shell nuclei in a wide mass range from 4He to 48Ca has been investigated by the RSPT3 with explicit NN+3N Hamiltonian. The RSPT3 calculations are performed within Hartree-Fock bases. The perturbative contribution of antisymmetrized Goldstone diagrams (diagrammatic expansion for RSPT) with normal-ordered interaction has been analyzed. We demonstrate that the normal-ordered two-body level (NO2B) approximation which neglects the residual three-body term can catch the main effect of full three-body force in RSPT calculation. We also present rigorous benchmarks for RSPT3 with non-perturbative coupled cluster and in-medium similarity renormalization group using the same chiral NNLOsat NO2B interaction. The three methods are in good agreement with each other for binding energies and radii. However, the RSPT3 provides an alternative that is computationally inexpensive but comparable in accuracy to state-of-the-art non-perturbative many-body methods.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex); Quantum Physics (quant-ph)
arXiv:
1810.08804 [pdf]
4 citations
02
[Submitted on 20 Oct 2018]
$p$ -shell hypernuclear structures using the Gogny-interaction shell model
X. Y. Chen🇨🇳 · Z. Zhou🇨🇳 · W. G. Jiang🇨🇳 · B. S. Hu🇨🇳 · F. R. Xu🇨🇳
We have systematically investigated the excitation spectra of $p$ -shell hypernuclei within the shell model based on the nucleon-nucleon and hyperon-nucleon interactions. For the effective nucleon-nucleon interaction, we adopt the Gogny force instead of the widely-used empirical $p$ -shell Cohen-Kurath interaction, while the hyperon-nucleon interaction takes the $Λ N$ interaction including the $Λ N$ - $Σ N$ coupling effect. We find that the shell model with the Gogny force can give reasonable descriptions of both spectra and binding energies of the $p$ -shell nuclei. With this confidence, combined with the $Λ N$ interaction, we have performed shell-model calculations for the $p$ -shell hypernuclei. We compare our results with $γ$ -ray data as well as various theoretical calculations, and explain recent experimental hypernuclear excitation spectra observed at JLab.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
arXiv:
1810.08806 [pdf]
J.Phys.G(2019)·3 citations
03
[Submitted on 20 Oct 2018]
Polarization of nucleons in the deuteron stripping reaction on nuclei
Valery I. Kovalchuk
A general analytical expression has been obtained in the diffraction approximation for the polarization of nucleons arising in the deuteron stripping reaction on nuclei at intermediate energies of the incident particles. A tabulated density distribution of the target nucleus and a realistic wave function of the deuteron with correct asymptotic limits at large internucleon distances were used in the calculations. The nucleon-nucleus phase shifts were calculated in the Glauber formalism using the double folding potential. The calculated angular dependencies for the vector analyzing power $A_{y}$ of the reaction $^{3} He (d, p)^{4} He$ are found to be in satisfactory agreement with the corresponding experimental data.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.08827 [pdf]
Russ.Phys.J.(2018)·1 citation
04
[Submitted on 21 Oct 2018]
Electroweak properties of pions in a nuclear medium
Parada T. P. Hutauruk🇰🇷 · Yongseok Oh🇰🇷 · K. Tsushima🇧🇷
The charge form factor and weak decay constant of the pion as well as the pion-quark coupling constant in symmetric nuclear matter are explored in the framework of the Nambu--Jona-Lasinio model, where the pion is described as a bound state of dressed quark-antiquark pair obtained by the Bethe-Salpeter equation. For the in-medium current quark properties, we adopt the quark-meson coupling model, which describes successfully many hadron properties in a nuclear medium. The pion decay constant and the pion-quark coupling constant are found to decrease with increasing density as well as the magnitude of the light quark condensate. But the pion mass is found to be insensitive to density up to $1.25$ times the normal nuclear density. The pion charge form factor in the space-like region is also explored and is found to have a similar $Q^{2}$ dependence as the form factor in vacuum showing $1/ Q^{2}$ -behavior in large $Q^{2}$ region, where $Q^{2}$ is the negative of the four-momentum transfer squared. The modifications of the charge radius of the charged pion in nuclear matter are then estimated and the root-mean-square radius at the normal nuclear density is predicted to be larger than that in vacuum by about 20\%.
Comments:
11 pages, REVTeX, to appear in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1810.08874 [pdf]
PRC(2019)·30 citations
05
[Submitted on 21 Oct 2018]
Effect of giant resonances on fluctuations of electromagnetic fields in heavy ion collisions
B.G. Zakharov🇷🇺
We perform quantum calculations of fluctuations of the electromagnetic fields in $AA$ collisions at RHIC and LHC energies. Calculations are performed with the help of the fluctuation-dissipation theorem accounting for the giant dipole and quadrupole resonances. We find that in the quantum picture the field fluctuations are much smaller than that predicted by the classical Monte-Carlo simulation with the Woods-Saxon nuclear density used in previous analyses.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1810.08942 [pdf]
JETP Lett.(2018)·2 citations
06
[Submitted on 22 Oct 2018]
Signature of bi-modal fission in Uranium nuclei
Alok Chakrabarti · Siddhartha Dechoudhury · Debasis Bhowmick · Vaishali Naik
We report here the signature of bi-modal fission, one asymmetric and the other symmetric, in Uranium nuclei in the mass range A = 230 to 236. The finding is unexpected and striking and is based on a model independent analysis of experimental mass distributions (cumulative yields) at various excitations from about 23 to 66 MeV in the alpha induced fission of 232Th. It has been found that the observed asymmetry in the mass distributions and the unusually narrow peak in the symmetry region, can both be explained in a consistent manner if one assumes: a) multi-chance fission, b) bi-modal fission at lower excitations (9 < E* < 25 MeV) for all the Uranium nuclei in the range A = 230 to 236, and c) that the shell effects get washed out completely beyond about 25 MeV of excitation resulting in symmetric fission. The analysis has allowed a quantitative estimation of the percentages of the asymmetric and the symmetric component in the bi-modal fission. It has been found that the bi-modal fission in Uranium nuclei is predominantly asymmetric (~ 85%), which contributes in a major way to the observed asymmetric peaks, while the ~15% bi-modal symmetric fission is primarily responsible for the observed narrow symmetric peak in the mass distributions. The unusually narrow symmetry peak in the mass distributions indicates that the symmetric bi-modal fission in Uranium nuclei must have proceeded from a configuration at the bi-modal symmetric saddle that is highly deformed with a well-developed neck.
Comments:
12 pages, 1 figure, 1 Table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.09209 [pdf]
J.Phys.G(2019)·1 citation
07
[Submitted on 22 Oct 2018]
Constrained correlated-Gaussians for hyperspherical calculations
Y. Suzuki · K. Varga
We formulate a hyperspherical approach within standard configuration interaction calculations aiming at a description of large-scale dynamics of $N$ -particle system. The channel wave function and the adiabatic channel energy are determined by solving a hyperradius-constrained eigenvalue problem of the adiabatic Hamiltonian. The needed matrix elements are analytically evaluated using correlated Gaussians with good orbital angular momentum and parity. The feasibility of the approach is tested in three- $α$ system. A spectrum of the adiabatic channel energies is determined depending on the degree of localization of the basis functions.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.09297 [pdf]
Few Body Syst.(2019)·4 citations
08
[Submitted on 22 Oct 2018]
Density-dependent NN-interaction from subleading chiral 3N-forces: short-range terms and relativistic corrections
N. Kaiser · V. Niessner
We derive from the subleading contributions to the chiral three-nucleon force (short-range terms and relativistic corrections, published in Phys. Rev. C84, 054001 (2011)) a density-dependent two-nucleon interaction $V_{med}$ in isospin-symmetric nuclear matter. The momentum and $k_{f}$ -dependent potentials associated with the isospin operators ( $1$ and $τ_{1} \cdot τ_{2}$ ) and five independent spin-structures are expressed in terms of loop functions, which are either given in closed analytical form or require at most one numerical integration. Our results for $V_{med}$ are most helpful to implement subleading chiral 3N-forces into nuclear many-body calculations.
Comments:
16 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.09412 [pdf]
PRC(2018)·22 citations
09
[Submitted on 18 Oct 2018] (cross-list from hep-ph)
In-medium properties of the low-lying strange, charm, and bottom baryons in the quark-meson coupling model
K. Tsushima🇧🇷
In-medium properties of the low-lying strange, charm, and bottom baryons in symmetric nuclear matter are studied in the quark-meson coupling (QMC) model. Results for the Lorentz-scalar effective masses, mean field potentials felt by the light quarks in the baryons, in-medium bag radii, and the lowest mode bag eigenvalues are presented for those calculated using the updated data. This study completes the in-medium properties of the low-lying baryons in symmetric nuclear matter in the QMC model, for the strange, charm and bottom baryons which contain one or two strange, one charm or one bottom quarks, as well as at least one light quark. Highlight is the prediction of the bottom baryon Lorentz-scalar effective masses, namely, the Lorentz-scalar effective mass of $Σ_{b}$ becomes smaller than that of $Ξ_{b}$ at moderate nuclear matter density, $m_{Σ_{b}}^{*} < m_{Ξ_{b}}^{*}$ , although in vacuum $m_{Σ_{b}} > m_{Ξ_{b}}$ . We study further the effects of the repulsive Lorentz-vector potentials on the excitation (total) energies of these bottom baryons.
Comments:
14 pages, 14 eps-figures. Version accepted for Phys. Rev. D. arXiv admin note: text overlap with arXiv:1706.02688
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1810.09260 [pdf]
PRD(2019)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE