Nuclear Theory·nucl-th

Tuesday·September 25, 2018

14 papers—8 primary·6 cross-listed

01
[Submitted on 22 Sept 2018]
Production of new neutron-rich heavy nuclei with $Z = 56 - 80$ in the multinucleon transfer reactions of $^{136}$ Xe+ $^{198}$ Pt
Cheng Li · Fan Zhang · Xinxin Xu · Jingjing Li · Gen Zhang · Bing Li · Cheikh A.T. Sokhna · Zhishuai Ge · Peiwei Wen · Feng-Shou Zhang
The multinucleon transfer reactions in collisions of $^{136}$ Xe+ $^{198}$ Pt at incident energies $E_{lab} =$ 5.25, 6.20, 7.98, 10.0, and 15.0 MeV/nucleon are investigated by using the improved quantum molecular dynamics model. It is found that 6.20 MeV/nucleon is the optimal incident energy for producing the neutron-rich heavy nuclei. About 80 unknown neutron-rich nuclei might be produced in this reaction with cross sections from 10 $^{- 6}$ to 10 $^{- 2}$ mb. The angular distributions of the neutron-rich isotopes are predicted.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.08373 [pdf]
PRC(2019)·32 citations
02
[Submitted on 22 Sept 2018]
Quantum and Coulomb repulsion effects on the bubble structures in $^{204, 206}$ Hg
X. Y. Wu · J. Xiang
The decreasing proton and charge densities from around 5.0 fm towards the center of $^{204, 206}$ Hg are investigated by a covariant density functional theory at the beyond mean-field level.The charge-density difference between $^{208}$ Pb and $^{204}$ Hg is improved significantly and a central depression is still visible in the ground-state density of $^{204, 206}$ Hg when the dynamic correlations associated with symmetry restoration and shape mixing are taken into account. For the $0_{2}^{+}$ and $2_{1}^{+}$ excited states of $^{204, 206}$ Hg, their densities remain decreasing from 5.0 fm to around 2.0 fm, but become flat in the interior region. The results show that the bubble structure in $^{204, 206}$ Hg within 2.0 fm is mainly attributed to the quantum effect, while that beyond 2.0 fm is formed by the Coulomb repulsion.
Comments:
7 pages, 7 figures, submitted to PRC
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.08393 [pdf]
PRC(2018)·5 citations
03
[Submitted on 22 Sept 2018]
Resonances of unbound quantum many-body systems of nuclei
B. S. Hu · Q. Wu · Z. H. Sun · F. R. Xu
Resonance is a general phenomenon which can happen in classic or quantum systems. An unbound many-body quantum system can undergo a self-resonant process. It has long been a challenge how to describe unbound many-body quantum systems in resonances. In this paper, we develop a novel first-principles method that is capable of describing resonant quantum systems. We exploit, for the first time, the advanced in-medium similarity renormalization group (IMSRG) in the complex-energy Gamow-Berggren representation with resonance and non-resonant continuum. The ab initio Gamow IMSRG has broad applications, such as, to the electromagnetic-interaction systems of atoms, molecules or quantum dots, and strong-interaction atomic nuclei. In the present work, we apply the method to loosely bound or unbound nuclear systems. Carbon and oxygen isotopes have been investigated with an optimized chiral effective field theory potential. The resonant states observed in neutron-rich 22O and 24O are well reproduced. The loose halo structure of the Borromean nucleus 22C is clearly seen by the density calculation, in which the continuum s-waves play a crucial role. Further, we predict low-lying resonant excited states in 22C. This method provides rigorous and tractable theoretical calculations for weakly-bound or unbound open quantum systems.
Subjects:
Nuclear Theory (nucl-th); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Experiment (nucl-ex); physics.optics (physics.optics)
arXiv:
1809.08405 [pdf]
J. Phys. G: Nucl. Part. Phys. 46 (2019) 1…·1 citation
04
[Submitted on 22 Sept 2018]
Anomalous internal conversion - the key to understanding the 209Bi riddle
F. F. Karpeshin · M.B.Trzhaskovskaya
Theory of anomalous internal conversion is developed, and extended for the description of the hyperfine splitting. Experimental data on the hyperfine splitting in the H- and Li-like heavy ions of 209Bi are analyzed in terms of the Bohr-Weisskopf effect. Agreement with the theory is achieved, scheduling light on the structure of the magnetization distribution over the nuclear volume.
Comments:
paper of 5 pages, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.08409 [pdf]
Phys.Atom.Nucl.(2018)·6 citations
05
[Submitted on 23 Sept 2018]
Forward-backward multiplicity fluctuations in ultra-relativistic nuclear collisions with wounded quarks and fluctuating strings
Martin Rohrmoser🇵🇱 · Wojciech Broniowski🇵🇱
We analyze a generic model where wounded quarks are amended with strings in which both end-point positions fluctuate in spatial rapidity. With the assumption that the strings emit particles independently of one another and with a uniform distribution in rapidity, we are able to analyze the model semi-analytically, which allows for its detailed understanding. Using as a constraint the one-body string emission functions obtained from the experimental data for collisions at $s_{N N} = 200$ GeV, we explore the two-body correlations for various scenarios of string fluctuations. We find that the popular measures used to quantify the longitudinal fluctuations are limited with upper and lower bounds and assume close values for the most likely models of the end-point distributions, which may explain why various approaches yield here very similar results.
Comments:
Figures updated
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1809.08666 [pdf]
PRC(2019)·11 citations
06
[Submitted on 24 Sept 2018]
Skyrme-RPA study of charged-current neutrino opacity in hot and dense supernova matter
Alan A. Dzhioev · Gabriel Martínez-Pinedo
Neutrino emission and their transport of energy to the supernova shock region are sensitive to the physics of hot and dense nuclear matter, which is a complex problem due to the strong correlations induced by nuclear forces. We derive charged-current opacities for electron neutrinos and antineutrinos in supernova matter using a self-consistent approach based on the Skyrme effective interaction. We include a mean field energy shift due to nuclear interaction and corrections due to RPA correlations. A complete treatment of the full Skyrme interaction, including a spin-orbit term, is given. To test the effect of RPA corrections, neutrino and antineutrino opacities are computed using different Skyrme parametrizations consistent with a number of infinite matter constraints.
Comments:
6 pages, 5 figures. Submitted to proceedings of International Conference on Nuclear Structure and Related Topics - NSRT18 (Bulgaria, Bourgas, June 3-9, 2018)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.08812 [pdf]
EPJ Web Conf.(2018)·5 citations
07
[Submitted on 24 Sept 2018]
$K ˉ D ˉ N$ molecular state as a " $uu d s c ˉ$ pentaquark" in a three-body calculation
Junko Yamagata-Sekihara🇯🇵 · Takayasu Sekihara🇯🇵
We predict a new three-body hadronic molecule composed of antikaon $K ˉ$ , anticharm meson $D ˉ$ , and nucleon $N$ with spin/parity $J^{P} = 1/ 2^{+}$ and isospin $I = 1/2$ . This state behaves like an explicit pentaquark state because its minimal quark configuration is $uu d s c ˉ$ or $u dd s c ˉ$ . Owing to the attraction between every pair of two hadrons, in particular the $K ˉ D ˉ$ attraction which dynamically generates $D_{s 0} (2317)^{-}$ and $K ˉ N$ attraction which dynamically generates $Λ (1405)$ , the $K ˉ D ˉ N$ system is bound, and its eigenenergy is calculated as $3244 - 17 i$ MeV in a nonrelativistic three-body potential model. We discuss properties of this $K ˉ D ˉ N$ quasibound state which emerge uniquely in three-body dynamics.
Comments:
12 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1809.08896 [pdf]
PRC(2019)·4 citations
08
[Submitted on 24 Sept 2018]
The microscopic mechanism behind the fission-barrier asymmetry (II): The rare-earth region $50 < Z < 82$ and $82 < N < 126$
T. Ichikawa · P. Möller
It is well known that most actinides fission into fragments of unequal size. The first attempt to understand this difference suggested that division leading to one of the fragments being near doubly magic $^{132}$ Sn is favored by gain in binding energy. After the Strutinsky shell-correction method was developed an alternative idea that gained popularity was that the fission saddle might be lower for mass-asymmetric shapes and that this asymmetry was preserved until scission. Recently it was observed [Phys. Rev. Lett. {\bf 105} (2010) 252502] that $^{180}$ Hg preferentially fissions asymmetrically in contradiction to the fragment-magic-shell expectation which suggested symmetric division peaked around $^{90}$ Zr, with its magic neutron number $N = 50$ , so it was presented as a "new type of asymmetric fission". However, in a paper [Phys. Lett. 34B (1971) 349] a "simple" microscopic mechanism behind the asymmetry of the actinide fission saddle points was proposed to be related the coupling between levels of type [40 $ΛΩ$ ] and [51 $ΛΩ$ ]. The paper then generalizes this idea and made the remarkable prediction that analogous features could exist in other regions. In particular it was proposed that in the rare-earth region couplings between levels of type [30 $ΛΩ$ ] and [41 $ΛΩ$ ] would favor mass-asymmetric outer saddle shapes. In this picture the asymmetry of $^{180}$ Hg is not a "new type of asymmetric fission" but of analogous origin as the asymmetry of actinide fission. This prediction has never been cited in the discussion of the recently observed fission asymmetries in the "new region of asymmetry", in nuclear physics also referred to as the rare-earth region. We show by detailed analysis that the mechanism of the saddle asymmetry in the sub-Pb region is indeed the one predicted half a century ago.
Comments:
9 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1809.08983 [pdf]
PLB(2019)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE