Nuclear Theory·nucl-th

Tuesday·December 15, 2015

15 papers—9 primary·6 cross-listed

01
[Submitted on 12 Dec 2015]
Impacts of the Nuclear Symmetry Energy on Neutron Star Crusts
Shishao Bao🇨🇳 · Hong Shen🇨🇳
Using the relativistic mean-field theory, we adopt two different methods, namely, the coexisting phase method and the self-consistent Thomas-Fermi approximation, to study the impacts of the nuclear symmetry energy on properties of neutron star crusts within a wide range of densities. It is found that the nuclear symmetry energy and its density slope play an important role in determining the pasta phases and the crust-core transition.
Comments:
4 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1512.03870 [pdf]
0 citations
02
[Submitted on 12 Dec 2015]
Self-consistent Thomas-Fermi Approximation for Equation of State at Subnuclear Densities
Zhao-wen Zhang · Hong Shen
The self-consistent Thomas-Fermi approximation is an essential method for studying the non-uniform nuclear matter with relativistic mean-field theory. In this method, the nucleon distribution in the Wigner-Seitz cell is obtained self-consistently. We make a detailed comparison between the present results and previous calculations in the Thomas-Fermi approximation with a parameterized nucleon distribution that has been adopted in the widely used Shen equation of state.
Comments:
4 pages, 2 figures, conference
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1512.03904 [pdf]
Acta Astron.Sin.Suppl.(2015)·0 citations
03
[Submitted on 12 Dec 2015]
Disappearance of Mott oscillations in sub-barrier elastic scattering of identical nuclei and atomic ions
M. S. Hussein · L. F. Canto · R. Donangelo · W. Mittig
The scattering of identical nuclei at low energies exhibits conspicuous Mott oscillations which can be used to investigate the presence of components in the predominantly Coulomb interaction arising from several physical effects. It is found that at a certain critical value of the Sommerfeld parameter the Mott oscillations disappear and the cross section becomes quite flat. We call this effect Transverse Isotropy (TI). The critical value of the Sommerfeld parameter at which TI sets in is found to be $η_{c} = 3 s + 2$ , where $s$ is the spin of the nuclei participating in the scattering. No TI is found in the Mott scattering of identical Fermionic nuclei. The critical center of mass energy corresponding to $η_{c}$ is found to be $E_{c}$ = 0.40 MeV for $α + α$ (s = 0) , 1.2 MeV for $^{6}$ Li + $^{6}$ LI (s = 1) and 7.1 MeV for $^{10}$ B + $^{10}$ B (s = 3). We further found that the inclusion of the nuclear interaction induces a significant modification in the TI. We suggest measurements at these sub-barrier energies for the purpose of extracting useful information about the nuclear interaction between light heavy ions. We also suggest extending the study of the TI to the scattering of identical atomic ions.
Comments:
9 pages, one figure, To be published in a special issue of Few Body Systems, "Weakly Bound Exotic Nuclei: Challenges for structure and reactions". This special issue is dedicated to the proceedings of a Workshop on Weakly-Bound Exotic Nuclei,Sunday, May 24 - Saturday, May 30, 2015 Natal, RN - Brazi
Subjects:
Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph); Quantum Physics (quant-ph)
arXiv:
1512.03960 [pdf]
Few Body Syst.(2016)·0 citations
04
[Submitted on 12 Dec 2015]
Novel Topological Effects in Dense QCD in a Magnetic Field
E.J. Ferrer🇺🇸 · V. de la Incera🇺🇸
We study the electromagnetic properties of dense QCD in the so-called Magnetic Dual Chiral Density Wave phase. This inhomogeneous phase exhibits a nontrivial topology that comes from the fermion sector due to the asymmetry of the lowest Landau level modes. The nontrivial topology manifests in the electromagnetic effective action via a chiral anomaly term $θ F^{μν} F ~_{μν}$ , with a dynamic axion field $θ$ given by the phase of the dual chiral density wave condensate. The coupling of the axion with the electromagnetic field leads to several macroscopic effects that include, among others, an anomalous, nondissipative Hall current, an anomalous electric charge, magnetoelectricity, and the formation of a hybridized propagating mode known as an axion polariton. Connection to topological insulators and Weyls semimetals, as well as possible implications for heavy-ion collisions and neutron stars are all highlighted.
Comments:
Section 3 completely revised, discussions added, and typos corrected
Subjects:
Nuclear Theory (nucl-th); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); cond-mat.mtrl-sci (cond-mat.mtrl-sci); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1512.03972 [pdf]
NPB(2018)·38 citations
05
[Submitted on 13 Dec 2015]
Description of resonant states in the shell model
I. A. Mazur · A. M. Shirokov · A. I. Mazur · J. P. Vary
A technique for describing scattering states within the nuclear shell model is proposed. This technique is applied to scattering of nucleons by $α$ particles based on ab initio No-Core Shell Model calculations of $^{5}$ He and $^{5}$ Li nuclei with JISP16 NN interaction.
Comments:
Submitted to Phys. Part. Nucl. Few misprints are corrected
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1512.03983 [pdf]
Phys.Part.Nucl.(2017)·26 citations
06
[Submitted on 13 Dec 2015]
Possible relevance of the softening of the sigma meson to $η$ decay into 3 $π$ in the nuclear medium
Shuntaro Sakai🇯🇵 · Teiji Kunihiro🇯🇵
We investigate the role of the softening of the scalar-isoscalar (sigma) meson in the $η \to π^{+} π^{-} π^{0}$ and $3 π^{0}$ decay widths in the symmetric nuclear medium using a linear sigma model. Our calculation shows that these decay widths in the nuclear medium increase by up to a factor of four to ten compared with those in the free space mainly depending on the mass of the sigma meson in the free space, which is an input parameter of the model. The enhancements are considerable even at a half of the normal nuclear density. Thus, the $η$ decay into $3 π$ could be a possible new probe for the chiral restoration in the nuclear medium. We find that the density dependence of the $η \to 3 π^{0}$ decay is moderate in comparison with that of $η \to π^{+} π^{-} π^{0}$ , although the former width is greater than the latter one at a given density. This is because the softening of the sigma meson causes cancellation of the terms appearing from the Bose symmetry in the $η \to 3 π^{0}$ decay. The difference between the density dependences should be helpful for experimental confirmation of the findings of the present study.
Comments:
27 pages, 10 figures. Tables 2,3,6, and 7 are added to show the input and determined parameters for the cases of $m_{σ}$ =441, 550, and 668 MeV, which is an input parameter in the present model. Figures 4 and 10 are added for the investigation of the effect of the nucleon mass modification in the nuclear medium and the dependence on the width of the sigma meson
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1512.04000 [pdf]
PTEP(2016)·1 citation
07
[Submitted on 13 Dec 2015]
Thermalization of parton spectra in the color-flux-tube model
Radoslaw Ryblewski🇵🇱
Detailed study of thermalization of the momentum spectra of partons produced via decays of the color flux tubes due to the Schwinger tunneling mechanism is presented. The collisions between particles are included in the relaxation time approximation specified by different values of the shear viscosity to entropy density ratio. At first we show that, to a good approximation, the transverse-momentum spectra of the produced patrons are exponential, irrespectively from the assumed value of the viscosity of the system and the freeze-out time. This thermal-like behaviour may be attributed to specific properties of the Schwinger tunneling process. In the next step, in order to check the approach of the system towards genuine local equilibrium, we compare the local slope of the model transverse-momentum spectra with the local slope of the fully equilibrated reference spectra characterised by the effective temperature that reproduces the energy density of the system. We find that the viscosity corresponding to the AdS/CFT lower bound is necessary for thermalization of the system within about two fermis.
Comments:
16 pages,14 figures, typos fixed, version submitted to JPG
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1512.04117 [pdf]
J.Phys.G(2016)·3 citations
08
[Submitted on 13 Dec 2015]
Electromagnetic contribution to charge symmetry violation in parton distributions
X.G. Wang🇦🇺 · A.W. Thomas🇦🇺 · R.D. Young🇦🇺
We report a calculation of the combined effect of photon radiation and quark mass differences on charge symmetry violation (CSV) in the parton distribution functions of the nucleon. Following a recent suggestion of Martin and Ryskin, the initial photon distribution is calculated in terms of coherent radiation from the proton as a whole, while the effect of the quark mass difference is based on a recent lattice QCD simulation. The distributions are then evolved to a scale at which they can be compared with experiment by including both QCD and QED radiation. Overall, at a scale of 5 GeV $^{2}$ , the total CSV effect on the phenomenologically important difference between the $d$ and $u$ -quark distributions is some 20\% larger than the value based on quark mass differences alone. In total these sources of CSV account for approximately 40\% of the NuTeV anomaly.
Comments:
5 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1512.04139 [pdf]
PLB(2016)·5 citations
09
[Submitted on 14 Dec 2015]
Collective and Single-particle Motion in Beyond Mean Field Approaches
J. Luis Egido · Marta Borrajo · Tomás R. Rodríguez
We present a novel nuclear energy density functional method to calculate spectroscopic properties of atomic nuclei. Intrinsic nuclear quadrupole deformations and rotational frequencies are considered simultaneously as the degrees of freedom within a symmetry conserving configuration mixing framework. The present method allows the study of nuclear states with collective and single-particle character. We calculate the fascinating structure of the semi-magic 44S nucleus as a first application of the method, obtaining an excellent quantitative agreement both with the available experimental data and with state-of-the-art shell model calculations.
Comments:
5 pages, 4 figures, accepted for publication in Phys. Rev. Lett
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1512.04232 [pdf]
PRL(2016)·62 citations

Affiliations

first authorsco-authorsvia INSPIRE