Nuclear Theory·nucl-th

Thursday·January 21, 2016

12 papers—7 primary·5 cross-listed

01
[Submitted on 19 Jan 2016]
Superfluid fission dynamics with microscopic approaches
C. Simenel · G. Scamps🇫🇷 · D. Lacroix🇫🇷 · A. S. Umar
Recent progresses in the description of the latter stage of nuclear fission are reported. Dynamical effects during the descent of the potential towards scission and in the formation of the fission fragments are studied with the time-dependent Hartree-Fock approach with dynamical pairing correlations at the BCS level. In particular, this approach is used to compute the final kinetic energy of the fission fragments. Comparison with experimental data on the fission of 258Fm are made.
Comments:
Proceeding of the "International Conference on Nuclear Structure and Related Topics" (NSRT15)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1601.05122 [pdf]
EPJ Web Conf.(2016)·4 citations
02
[Submitted on 20 Jan 2016]
Beyond Wigner's isobaric multiplet mass equation: Effect of charge-symmetry-breaking interaction and Coulomb polarization
J. M. Dong · J. Z. Gu · Y. H. Zhang · W. Zuo · L. J. Wang · Yu. A. Litvinov · Y. Sun
The quadratic form of the isobaric multiplet mass equation (IMME), which was originally suggested by Wigner and has been generally regarded as valid, is seriously questioned by recent high-precision nuclear mass measurements. The usual resolution to this problem is to add empirically the cubic and quartic $T_{z}$ -terms to characterize the deviations from the IMME, but finding the origin of these terms remains an unsolved difficulty. Based on a strategy beyond the Wigner's first-order perturbation, we derive explicitly the cubic and quartic $T_{z}$ -terms. These terms are shown to be generated by the effective charge-symmetry breaking and charge-independent breaking interactions in nuclear medium combined with the Coulomb polarization effect. Calculations for the $s d$ - and lower $f p$ -shells explore a systematical emergence of the cubic $T_{z}$ -term, suggesting a general deviation from the original IMME. Intriguingly, the magnitude of the deviation exhibits an oscillation-like behavior with mass number, modulated by the shell effect.
Comments:
13 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1601.05167 [pdf]
PRC(2019)·16 citations
03
[Submitted on 20 Jan 2016]
Time-dependent Hartree-Fock Study of Octupole Vibrations in doubly magic nuclei
C. Simenel · J. Buete · K. Vo-Phuoc
Octupole vibrations are studied in some doubly magic nuclei using the time-dependent Hartree-Fock (TDHF) theory with a Skyrme energy density functional. Through the use of the linear response theory, the energies and transition amplitudes of the low-lying vibrational modes for each of the nuclei were determined. Energies were found to be close to experimental results. However, transition amplitudes, quantified by the deformation parameter $β_{3}$ , are underestimated by TDHF. A comparison with single-particle excitations on the Hartree-Fock ground-state shows that the collective octupole vibrations have their energy lowered due to attractive RPA residual interaction.
Comments:
Proceeding of the Heavy-Ions Accelerator Symposium 2015
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1601.05185 [pdf]
EPJ Web Conf.(2016)·1 citation
04
[Submitted on 20 Jan 2016]
A theoretical analysis of mid-mass neutron halos. What changes going from few- to many-body systems regarding neutron halos?
T. Duguet
The present contribution summarizes the content and slightly updates the discussion of a recently proposed theoretical analysis of the halo phenomenon in many-fermion systems. We focus here on applications to potential neutron halos in mid-mass nuclei.
Comments:
17 pages, 19 figures. arXiv admin note: substantial text overlap with arXiv:nucl-th/0702050
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1601.05267 [pdf]
Few Body Syst.(2016)·1 citation
05
[Submitted on 20 Jan 2016]
Search for scaling onset in exclusive reactions with the lightest nuclei
Yu.N. Uzikov🇷🇺
The dimensional scaling of the differential cross sections of binary reactions $d σ / d t \sim s^{- (n - 2)}$ , where $n$ is given by constituent quark counting rules, was predicted for asymptotically high energies $s ≫ m_{i}$ and transferred momenta $- t ≫ m_{i}^{2}$ at $t / s = co n s t$ (here $s$ and $t$ are the Mandelstam variables and $m_{i}$ denotes a hadron mass), but manifested itself at surprisingly moderate energies of few GeV at large fixed cms angles $θ_{c m} \sim 9 0^{\circ}$ . This behaviour is observed not only in reactions with free hadrons, but with the deuteron and $^{3} H e$ too both for electromagnetic and pure hadronic interactions. One may suppose that observed scaling points out to effective restoration of near-conformal and, probably, chiral symmetry in these processes. A systematical experimental study of the scaling behaviour of the reactions with the deuteron, $^{3} H$ , $^{3} H e$ , and $^{4} H e$ nuclei is still absent. We consider a possibility to carry out this study in $dd$ collisions at the JINR Nuclotron.
Comments:
5 pages, 3 eps-figures, accepted by the European Physical Journal A
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1601.05280 [pdf]
EPJA(2016)·3 citations
06
[Submitted on 19 Jan 2016]
The Hyperon Puzzle in Neutron Stars
Ignazio Bombaci🇮🇹
The so called "hyperon puzzle", i.e. the difficulty to reconcile the measured masses of neutron stars (NSs) with the presence of hyperons in their interiors, is one of the hot topics in astrophysics which is stimulating copious experimental and theoretical research in hypernuclear physics. After illustrating the origin of the hyperon puzzle, I discuss some of its possible solutions, and particularly those related to the role of hyperonic two- and three-body interactions on the equation of state of dense matter. Afterward, I discuss a possibility to circumvent the hyperon puzzle allowing for the presence of strangeness in NSs in the form of deconfined strange quark matter, and thus considering the so called quark stars, i.e. hybrid stars or strange stars. Finally I discuss the astrophysical consequences of the possible conversion process of an hadronic star to a quark star.
Comments:
Invited keynote talk at the Topical Session "Hyperon puzzle in Neutron Stars" at the 12th International Conference on Hypernuclear and Strange Particle Physics (HYP2015), September 7-12, 2015, Sendai, Japan. arXiv admin note: text overlap with arXiv:1601.04559
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1601.05339 [pdf]
JPS Conf.Proc.(2017)·81 citations
07
[Submitted on 20 Jan 2016]
Origin of the mass splitting of elliptic anisotropy in a multiphase transport model
Hanlin Li🇨🇳 · Liang He🇺🇸 · Zi-Wei Lin🇺🇸 · Denes Molnar🇺🇸 · Fuqiang Wang🇺🇸 · Wei Xie🇺🇸
The mass splitting of elliptic anisotropy ( $v_{2}$ ) at low transverse momentum is considered as a hallmark of hydrodynamic collective flow. We investigate a multiphase transport (AMPT) model where the $v_{2}$ is mainly generated by an anisotropic escape mechanism, not of the hydrodynamic flow nature, and where mass splitting is also observed. We demonstrate that the $v_{2}$ mass splitting in AMPT is small right after hadronization (especially when resonance decays are included); the mass splitting mainly comes from hadronic rescatterings, even though their contribution to the overall charged hadron $v_{2}$ is small. These findings are qualitatively the same as those from hybrid models that combine hydrodynamics with a hadron cascade. We further show that there is no qualitative difference between heavy ion collisions and small system collisions. Our results indicate that the $v_{2}$ mass splitting is not a unique signature of hydrodynamic collective flow and thus cannot distinguish whether the elliptic flow is generated mainly from hydrodynamics or the anisotropic parton escape.
Comments:
5 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1601.05390 [pdf]
PRC(2016)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE

Superfluid fission dynamics with microscopic approaches

Beyond Wigner's isobaric multiplet mass equation: Effect of charge-symmetry-breaking interaction and Coulomb polarization

Time-dependent Hartree-Fock Study of Octupole Vibrations in doubly magic nuclei

A theoretical analysis of mid-mass neutron halos. What changes going from few- to many-body systems regarding neutron halos?

Search for scaling onset in exclusive reactions with the lightest nuclei

The Hyperon Puzzle in Neutron Stars

Origin of the mass splitting of elliptic anisotropy in a multiphase transport model

Affiliations