Nuclear Theory·nucl-th

Tuesday·November 7, 2017

22 papers—8 primary·14 cross-listed

01
[Submitted on 4 Nov 2017]
Semiclassical unified description of wobbling motion in even-even and even-odd nuclei
A. A. Raduta · R. Poenaru · L. Gr. Ixaru
A unitary description for wobbling motion in even-even and even-odd nuclei is presented. In both cases compact formulas for wobbling frequencies are derived. The accuracy of the harmonic approximation is studied for the yrast as well as for the excited bands in the even-even case. Important results for the structure of the wave function and its behavior inside the two wells of the potential energy function corresponding to the Bargmann representation are pointed out. Applications to $^{158}$ Er and $^{163}$ Lu reveal a very good agreement with available data. Indeed, the yrast energy levels in the even-even case and the first four triaxial super-deformed bands, TSD1,TSD2,TSD3 and TSD4, are realistically described. Also, the results agree with the data for the E2 and M1 intra- as well as inter-band transitions. Perspectives for the formalism development and an extensive application to several nuclei from various regions of the nuclides chart are presented.
Comments:
47 pages, 25 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1711.01425 [pdf]
PRC(2017)·24 citations
02
[Submitted on 4 Nov 2017]
Photo- and Electro-excitation of Bound Neutrons and Protons
Satoshi X. Nakamura (Universidade Cruzeiro do Sul)
Data for pion photo-productions off the neutron ( $γ n \to π N$ ) have been primarily extracted from deuteron-target data ( $γ d \to π N N$ ) by applying kinematical cuts thereby isolating the quasi-free samples. We critically examine if the neutron-target data obtained through this conventional procedure can be contaminated by final state interactions (FSI) and/or the kinematical cuts. The analysis is conducted with a theoretical model for $γ d \to π N N$ that takes account of the impulse mechanisms supplemented by the $N N$ and $π N$ rescattering mechanisms. We show that the FSI effects still visibly remain in the extracted $γ$ ` $n$ ' $\to π N$ unpolarized cross sections and polarization asymmetries $E$ even after the kinematical cuts are applied. We also find the FSI effects on $γ$ ` $n$ ' $\to π^{0} n$ can be somewhat different from those on $γ$ ` $p$ ' $\to π^{0} p$ .
Comments:
8 pages, 15 figures, published version, Contribution to the Proceedings for 11th International Workshop on the Physics of Excited Nucleons (NSTAR 2017), August 20-23, 2017, Columbia, USA
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1711.01480 [pdf]
Few Body Syst.(2018)·2 citations
03
[Submitted on 5 Nov 2017]
Analytical attractor and the divergence of the slow-roll expansion in relativistic hydrodynamics
Gabriel S. Denicol (Niteroi, Fluminense U.)🇧🇷 · Jorge Noronha (Sao Paulo U.)🇧🇷
We find the general analytical solution of the viscous relativistic hydrodynamic equations (in the absence of bulk viscosity and chemical potential) for a Bjorken expanding fluid with a constant shear viscosity relaxation time. We analytically determine the hydrodynamic attractor of this fluid and discuss its properties. We show for the first time that the slow-roll expansion, a commonly used approach to characterize the attractor, diverges. This is shown to hold also in a conformal plasma. The gradient expansion is found to converge in an example where causality and stability are violated.
Comments:
22 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
1711.01657 [pdf]
PRD(2018)·77 citations
04
[Submitted on 6 Nov 2017]
Statistical analysis of excitation energies in the actinide and rare-earth nuclei
A.I. Levon · A.G. Magner · S.V. Radionov
Statistical analysis of distributions of the collective states in the actinide and rare-earth nuclei is performed in terms of the nearest neighbor spacing distribution (NNSD). Several approximations, such as the linear approach to the level repulsion density and that suggested by Brody to the NNSDs were applied for the analysis. We found an intermediate character of the experimental spectra between the order and the chaos for a number of the rare-earth and actinide nuclei. They are more close to the Wigner distribution for energies limited by 3 MeV, and to the Poisson distribution for data including higher excitation energies and higher spins. The latter is in agreement with the theoretical calculations. These features are confirmed by the cumulative distributions, where the Wigner contribution dominates at smaller spacings while the Poisson one is more important at larger spacings.
Comments:
11 pages, 6 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1711.01848 [pdf]
PRC(2018)·7 citations
05
[Submitted on 3 Nov 2017]
Including particle-vibration coupling in the Fayans functional. Odd-even mass differences of semi-magic nuclei
E.E. Saperstein · M. Baldo · S.S. Pankratov · S.V. Tolokonnikov
A method to evaluate the particle-phonon coupling (PC) corrections to the single-particle energies in semi-magic nuclei, based on the direct solution of the Dyson equation with PC corrected mass operator, is presented. It is used for finding the odd-even mass difference between even Pb and Sn isotopes and their odd-proton neighbors. The Fayans energy density functional (EDF) DF3-a is used which gives rather highly accurate predictions for these mass differences already at the mean-field level. In the case of the lead chain, account for the PC corrections induced by the low-laying phonons $2_{1}^{+}$ and $3_{1}^{-}$ makes agreement of the theory with the experimental data significantly better. For the tin chain, the situation is not so definite. In this case, the PC corrections make agreement better in the case of the addition mode but they spoil the agreement for the removal mode. We discuss the reason of such a discrepancy.
Comments:
10 pages, 3 figures, 11 tables. arXiv admin note: substantial text overlap with arXiv:1710.09159
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1711.01953 [pdf]
PRC(2018)·2 citations
06
[Submitted on 3 Nov 2017]
Supernova {\beta}^- decay of nuclides 53Fe, 54Fe, 55Fe, and 56Fe in strongly screened plasma
Jing-Jing Liu · Dong-Mei Liu
The electron screening strong effect on the electron energy and threshold energy of the beta decay reaction. in this paper, we study the $β^{-}$ decay rates of some iron isotopes. The electron screening beta decay rates increase by about two orders of magnitude. The strong screening beta decay rates due to Q-value correction are by more than one order of magnitude higher than those of without Q-value correction.
Comments:
10 pages, 45 figures, accepted for publication in Resarch in Astronomy and Astrophysics
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1711.01955 [pdf]
Res.Astron.Astrophys.(2018)·18 citations
07
[Submitted on 6 Nov 2017]
Review of the theoretical heavy-ion physics
E. L. Bratkovskaya🇩🇪 · W. Cassing🇩🇪 · P. Moreau🇩🇪 · T. Song🇩🇪
In this contribution we briefly give an overview of the theoretical models used to describe experimental data from heavy-ion collisions from $s_{N N} \approx$ 4 GeV to ultra-relativistic energies of $s_{N N} \approx$ 5 TeV. We highlight the successes and problems of statistical or hadron-resonance gas models, address the results of macroscopic approaches like hydrodynamics (in different hybrid combinations) as well as the results from microscopic transport approaches in comparison to experimental data. Finally, the transport coefficients like shear $η$ and bulk viscosity $ζ$ - entering the macroscopic models - are confronted with results from lattice QCD in thermal equilibrium for vanishing chemical potential.
Comments:
Contribution to the Proceedings of the ICPPA conference: The 3rd International Conference on Particle Physics and Astrophysics (ICPPA-2017), Moscow, Russia, 2-5 October 2017
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1711.01976 [pdf]
KnE Energ.Phys.(2018)·3 citations
08
[Submitted on 6 Nov 2017]
Ab initio calculation of neutral-current $ν$ - $^{12}$ C inclusive quasielastic scattering
A. Lovato🇮🇹 · S. Gandolfi🇺🇸 · J. Carlson🇺🇸 · Ewing Lusk🇺🇸 · Steven C. Pieper🇺🇸 · R. Schiavilla🇺🇸
Quasielastic neutrino scattering is an important aspect of the experimental program to study fundamental neutrino properties including neutrino masses, mixing angles, the mass hierarchy and CP-violating phase. Proper interpretation of the experiments requires reliable theoretical calculations of neutrino-nucleus scattering. In this paper we present calculations of response functions and cross sections by neutral-current scattering of neutrinos off $^{12}$ C. These calculations are based on realistic treatments of nuclear interactions and currents, the latter including the axial-, vector-, and vector-axial interference terms crucial for determining the difference between neutrino and anti-neutrino scattering and the CP-violating phase. We find that the strength and energy-dependence of two-nucleon processes induced by correlation effects and interaction currents are crucial in providing the most accurate description of neutrino-nucleus scattering in the quasielastic regime.
Comments:
5 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex)
arXiv:
1711.02047 [pdf]
PRC(2018)·64 citations

Affiliations

first authorsco-authorsvia INSPIRE