Nuclear Theory·nucl-th

Friday·March 11, 2016

9 papers—6 primary·3 cross-listed

01
[Submitted on 10 Mar 2016]
Decay dynamics of the unbound $^{25}$ O and $^{26}$ O nuclei
K. Hagino · H. Sagawa
We study the ground and excited resonance states of $^{26}$ O with a three-body model of $^{24}$ O+n+n taking into account the coupling to the continuum. To this end, we use the new experimental data for the invariant mass spectroscopy of the unbound $^{25}$ O and $^{26}$ O nuclei, and present an update of three-body model calculations for the two-neutron decay of the $^{26}$ O nucleus. With the new model inputs determined with the ground state decay of $^{26}$ O, we discuss the di-neurtron correlations and a halo nature of this nucleus, as well as the structure of the excited states. For the energy of the 2 $^{+}$ state, we achieve an excellent agreement with the experimental data with this calculation. We show that the 2 $^{+}$ state consists predominantly of the $(d_{3/2})^{2}$ configuration, for which the pairing interaction between the valence neutrons slightly decreases its energy from the unperturbed one. We also discuss the structure of excited 0 $^{+}$ states of the $^{26}$ O nucleus. In particular, we show the existence of an excited 0 $^{+}$ state at 3.38 MeV, which is mainly composed of the $(f_{7/2})^{2}$ configuration.
Comments:
12 pages, 13 figures. To appear in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1603.03120 [pdf]
PRC(2016)·34 citations
02
[Submitted on 10 Mar 2016]
Electric dipole moment of $^{13}$ C
Nodoka Yamanaka🇫🇷 · Taiichi Yamada🇯🇵 · Emiko Hiyama🇯🇵 · Yasuro Funaki🇨🇳
We calculate for the first time the electric dipole moment (EDM) of $^{13}$ C generated by the isovector CP-odd pion exchange nuclear force in the $α$ -cluster model, which describes well the structures of low lying states of the $^{13}$ C nucleus. The linear dependence of the EDM of $^{13}$ C on the neutron EDM and the isovector CP-odd nuclear coupling is found to be $d_{^{13} C} = - 0.33 d_{n} - 0.0020 G ˉ_{π}^{(1)}$ . The linear enhancement factor of the CP-odd nuclear coupling is smaller than that of the deuteron, due to the difference of the structure between the $1/ 2_{1}^{-}$ state and the opposite parity ( $1/ 2^{+}$ ) states. We clarify the role of the structure played in the enhancement of the EDM. This result provides good guiding principles to search for other nuclei with large enhancement factor. We also mention the role of the EDM of $^{13}$ C in determining the new physics beyond the standard model.
Comments:
11 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1603.03136 [pdf]
PRC(2017)·29 citations
03
[Submitted on 10 Mar 2016]
Energy spectra and quadrupole transition probabilities of 124-130Ba
H. Sabri · M. Seidi
In this paper, we have studied the energy spectra and B(E2) transition probabilities of 124-130Ba isotopes in the shape phase transition region between the spherical and gamma unstable deformed shapes. We have used a transitional Interacting Boson Model Hamiltonian which is based on affine SU(1,1) Lie Algebra in the both IBM-1 and 2 versions and also the Catastrophe theory in combination with a coherent state formalism to generate energy surfaces and determine the exact values of control parameters. Our results for control parameters suggest a combination of U(5) and SO(6) dynamical symmetries in this isotopic chain. Also, the theoretical predictions can be rather well reproduce the experimental counterparts when the control parameter is approached to the SO(6) limit.
Comments:
22 pages, 3 figures, 5tables. arXiv admin note: text overlap with arXiv:1509.02282; text overlap with arXiv:1507.06933 by other authors without attribution
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1603.03193 [pdf]
IJMPE(2016)·6 citations
04
[Submitted on 10 Mar 2016]
$^{9}$ Be elastic scattering on $^{208}$ Pb and $^{27}$ Al within a four-body reaction framework
J. Casal · M. Rodríguez-Gallardo · J. M. Arias
We investigate the low-energy $^{9}$ Be elastic scattering on two different targets (heavy, light) within a four-body framework using the Continuum-Discretized Coupled-Channels (CDCC) method. The $^{9}$ Be projectile is described in a $α + α + n$ three-body model using the analytical transformed harmonic oscillator (THO) basis in hyperspherical coordinates. We show that continuum couplings are important to describe the elastic cross section, especially at low energies and on heavy targets. The dipolar contribution to the elastic cross section at energies around the Coulomb barrier is important but small compared to the case of halo nuclei. The effect of the projectile low-energy resonances is also relevant. The agreement with the available experimental data supports the reliability of the method to describe reactions induced by three-body projectiles including more than one charged particle.
Comments:
9 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1603.03261 [pdf]
PRC(2015)·31 citations
05
[Submitted on 10 Mar 2016]
Scaling limit analysis of Borromean halos
L. A. Souza · F. F. Bellotti · T. Frederico · M. T. Yamashita · L. Tomio
The analysis of the core recoil momentum distribution of neutron-rich isotopes of light exotic nuclei is performed within a model of the halo nuclei described by a core and two neutrons dominated by the $s -$ wave channel. We adopt the renormalized three-body model with a zero-range force, that accounts for the universal Efimov physics. This model is applicable to nuclei with large two-neutron halos compared to the core size, and a neutron-core scattering length larger than the interaction range. The halo wave function in momentum space is obtained by using as inputs the two-neutron separation energy and the energies of the singlet neutron-neutron and neutron-core virtual states. Within our model, we obtain the momentum probability densities for the Borromean exotic nuclei Lithium-11 ( $^{11}$ Li), Berylium-14 ( $^{14}$ Be) and Carbon-22 ( $^{22}$ C). A fair reproduction of the experimental data was obtained in the case of the core recoil momentum distribution of $^{11}$ Li and $^{14}$ Be, without free parameters. By extending the model to $^{22}$ C, the combined analysis of the core momentum distribution and matter radius suggest (i) a $^{21}$ C virtual state well below 1 MeV; (ii) an overestimation of the extracted matter $^{22}$ C radius; and (iii) a two-neutron separation energy between 100 and 400 keV.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1603.03407 [pdf]
Few Body Syst.(2016)·2 citations
06
[Submitted on 10 Mar 2016]
Octupole deformation in the ground states of even-even nuclei: a global analysis within the covariant density functional theory
S.E. Agbemava · A.V. Afanasjev · P. Ring
A systematic investigation of octupole deformed nuclei is presented for even-even systems with $Z \leq 106$ located between the two-proton and two-neutron drip lines. For this study we use five most up-to-date covariant energy density functionals of different types, with a non-linear meson coupling, with density dependent meson couplings, and with density-dependent zero-range interactions. Pairing correlations are treated within relativistic Hartree-Bogoliubov (RHB) theory based on an effective separable particle-particle interaction of finite range. This allows us to assess theoretical uncertainties within the present covariant models for the prediction of physical observables relevant for octupole deformed nuclei. In addition, a detailed comparison with the predictions of non-relativistic models is performed. A new region of octupole deformation, centered around $Z \sim 98, N \sim 196$ is predicted for the first time. In terms of its size in the $(Z, N)$ plane and the impact of octupole deformation on binding energies this region is similar to the best known region of octupole deformed nuclei centered at $Z \sim 90, N \sim 136$ . For the later island of octupole deformed nuclei, the calculations suggest substantial increase of its size as compared with available experimental data.
Comments:
26 pages, 19 figures, 1 Table, submitted to Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1603.03414 [pdf]
PRC(2016)·129 citations

Affiliations

first authorsco-authorsvia INSPIRE

Decay dynamics of the unbound 25O and 26O nuclei

Electric dipole moment of 13C

Energy spectra and quadrupole transition probabilities of 124-130Ba

9Be elastic scattering on 208Pb and 27Al within a four-body reaction framework

Scaling limit analysis of Borromean halos

Octupole deformation in the ground states of even-even nuclei: a global analysis within the covariant density functional theory

Affiliations

Decay dynamics of the unbound $^{25}$ O and $^{26}$ O nuclei

Electric dipole moment of $^{13}$ C

$^{9}$ Be elastic scattering on $^{208}$ Pb and $^{27}$ Al within a four-body reaction framework