Nuclear Theory·nucl-th

Wednesday·May 18, 2016

11 papers—8 primary·3 cross-listed

01
[Submitted on 16 May 2016]
Natural orbital description of the halo nucleus 6He
Ch. Constantinou · M. A. Caprio · J. P. Vary · P. Maris
Ab initio calculations of nuclei face the challenge of simultaneously describing strong short-range internucleon correlations and the long-range properties of weakly-bound halo nucleons. Natural orbitals, which diagonalize the one-body density matrix, provide a basis which is better matched to the physical structure of the many-body wave function. We demonstrate that the use of natural orbitals significantly improves convergence for ab initio no-core configuration interaction calculations of the neutron halo nucleus 6He, relative to the traditional oscillator basis.
Comments:
6 pages, 4 figures; presented at the Symposium on Nuclear Dynamics and Thermodynamics, Huizhou, China, December 11, 2016; as published in Nucl. Sci. Tech
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1605.04976 [pdf]
Nucl.Sci.Tech.(2017)·29 citations
02
[Submitted on 17 May 2016]
Productions of J/psi mesons in p-Pb collisions at 5 TeV
Fu-Hu Liu🇨🇳 · Hai-Ling Lao🇨🇳 · Roy A. Lacey🇺🇸
The rapidity distributions of $J / ψ$ mesons produced in proton-lead ( $p$ -Pb) collisions at center-of-mass energy per nucleon pair $s_{N N} = 5$ TeV are studied by using a multisource thermal model and compared with the experimental data of the LHCb and ALICE Collaborations. Correspondingly, the pseudorapidity distributions are accurately obtained from the parameters extracted from the rapidity distributions. At the same time, the transverse momentum distributions in the same experiments are described by the simplest Erlang distribution which is the folding result of two exponential distributions which are contributed by the target and projectile partons respectively.
Comments:
14 pages, 3 figures. International Journal of Modern Physics E, accepted
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1605.05020 [pdf]
IJMPE(2016)·3 citations
03
[Submitted on 17 May 2016]
Shell-structure of one-particle resonances in deformed potentials
Ikuko Hamamoto
Shell structure of low-lying neutron resonant levels in axially-symmetric quadrupole-deformed potentials is discussed, which seems analogous to that of weakly-bound neutrons. As numerical examples, nuclei slightly outside the neutron-drip-line, $_{12}^{39}$ Mg $_{27}$ and $_{6}^{21}$ C $_{15}$ , are studied. For the lowest resonance I obtain $I^{π}$ = $Ω^{π}$ = 5/2 $^{-}$ for $^{39}$ Mg which is likely to be prolately deformed, while $I^{π}$ = $Ω^{π}$ = 1/2 $^{+}$ may be assigned to the nucleus $^{21}$ C which may be oblately deformed. Consequently, $^{21}$ C will not be observed as a recognizable resonant state, in agreement with the experimental information.
Comments:
16 pages and 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1605.05033 [pdf]
PRC(2016)·21 citations
04
[Submitted on 17 May 2016]
Interplay between tensor force and deformation in even-even nuclei
Rémi N. Bernard · Marta Anguiano
In this work we study the effect of the nuclear tensor force on properties related with deformation. We focus on isotopes in the Mg, Si, S, Ar, Sr and Zr chains within the Hartree-Fock-Bogoliubov theory using the D1ST2a Gogny interaction. Contributions to the tensor energy in terms of saturated and unsaturated subshells are analyzed. Like-particle and proton-neutron parts of the tensor term are independently examinated. We found that the tensor term may considerably modify the potential energy landscapes and change the ground state shape. We analyze too how the pairing characteristics of the ground state change when the tensor force is included.
Comments:
46 pages, published in Nuclear Physics A (2016)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1605.05041 [pdf]
0 citations
05
[Submitted on 17 May 2016]
Model dependence of the neutron-skin thickness on the symmetry energy
C. Mondal · B. K. Agrawal · M. Centelles · G. Colò · X. Roca-Maza · N. Paar · X. Viñas · S. K. Singh · S. K. Patra
The model dependence in the correlations of the neutron-skin thickness in heavy nuclei with various symmetry energy parameters is analyzed by using several families of systematically varied microscopic mean field models. Such correlations show a varying degree of model dependence once the results for all the different families are combined. Some mean field models associated with similar values of the symmetry energy slope parameter at saturation density $L$ , and pertaining to different families, yield a greater-than-expected spread in the neutron-skin thickness of the $^{208}$ Pb nucleus. The effective value of the symmetry energy slope parameter $L_{eff}$ , determined by using the nucleon density profiles of the finite nucleus and the density derivative $S^{'} (ρ)$ of the symmetry energy starting from about saturation density up to low densities typical of the surface of nuclei, seems to account for the spread in the neutron-skin thickness for the models with similar $L$ . The differences in the values of $L_{eff}$ are mainly due to the small differences in the nucleon density distributions of heavy nuclei in the surface region and the behavior of the symmetry energy at subsaturation densities.
Comments:
10 pages including 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1605.05048 [pdf]
PRC(2016)·48 citations
06
[Submitted on 17 May 2016]
Shape Coexistence in 78 Ni and the new Island of Inversion
F Nowacki (UNISTRA, IPHC)🇫🇷 · A Poves🇪🇸 · E Caurier (UNISTRA, IPHC)🇫🇷 · B Bounthong (UNISTRA, IPHC)🇫🇷
Large Scale Shell Model calculations (SM-CI) predict that the region of deformation which comprises the heaviest Chromium and Iron isotopes at and beyond N=40 will merge with a new one at N=50 in an astonishing parallel to the N=20 and N=28 case in the Neon and Magnesium isotopes. We propose a valence space including the full pf-shell for the protons and the full sdg shell for the neutrons; which represents a comeback of the the harmonic oscillator shells in the very neutron rich regime. The onset of deformation is understood in the framework of the algebraic SU3-like structures linked to quadrupole dominance. Our calculations preserve the doubly magic nature of the ground state of 78 Ni, which, however, exhibits a well deformed prolate band at low excitation energy, providing a striking example of shape coexistence far from stability.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1605.05103 [pdf]
PRL(2016)·144 citations
07
[Submitted on 17 May 2016]
Anisotropy of Low Energy Direct Photons in Relativistic Heavy Ion Collisions
T. Koide🇧🇷 · T. Kodama🇧🇷
We investigate the behavior of low energy photons radiated by the deceleration processes of two colliding nuclei in relativistic heavy ion collisions using the Wigner function approach for electromagnetic radiation fields. The angular distribution reveals the information of the initial geometric configurations. Such a property is reflected in the anisotropic parameter $v_{2}$ , showing an increasing $v_{2}$ as energy decreases, which is a behavior qualitatively different from $v_{2}$ from hadrons produced in the collisions.
Comments:
7 pages,5 figures, one reference was added, accepted for publication in J. Phys. G
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1605.05127 [pdf]
J.Phys.G(2016)·14 citations
08
[Submitted on 17 May 2016]
Electric quadrupole transitions of the Bohr Hamiltonian with Manning-Rosen potential
M. Chabab · A. El Batoul · A. Lahbas · M. Oulne
Analytical expressions of the wave functions are derived for a Bohr Hamiltonian with the Manning{Rosen potential in the cases of {\gamma}-unstable nuclei and axially symmetric prolate deformed ones with {\gamma}=0. By exploiting the results we have obtained in a recent work on the same theme Ref. [1], we have calculated the B(E2) transition rates for 34 {\gamma}-unstable and 38 rotational nuclei and compared to experimental data, revealing a qualitative agreement with the experiment and phase transitions within the ground state band and showing also that the Manning-Rosen potential is more appropriate for such calculations than other potentials.
Comments:
20 pages, 2 figures, 4 Tables (to appear in Nuclear Physics A)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1605.05270 [pdf]
NPA(2016)·27 citations

Affiliations

first authorsco-authorsvia INSPIRE