Nuclear Theory·nucl-th

Wednesday·May 18, 2016

11 papers—8 primary·3 cross-listed

01
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.
nucl-thNucl.Sci.Tech.(2017)·29 citations
02
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.
nucl-thhep-exhep-phnucl-exIJMPE(2016)·3 citations
03
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.
nucl-thPRC(2016)·21 citations
04
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.
nucl-th0 citations
05
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.
nucl-thPRC(2016)·48 citations
06
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.
nucl-thnucl-exPRL(2016)·144 citations
07
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.
nucl-thhep-exhep-phJ.Phys.G(2016)·14 citations
08
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.
nucl-thNPA(2016)·27 citations
09
Polarization and dilepton anisotropy in pion-nucleon collisions
Enrico Speranza🇩🇪 · Miklós Zétényi🇩🇪 · Bengt Friman🇩🇪
Hadronic polarization and the related anisotropy of the dilepton angular distribution are studied for the reaction $π N \to N e^{+} e^{-}$ . We employ consistent effective interactions for baryon resonances up to spin-5/2, where non-physical degrees of freedom are eliminated, to compute the anisotropy coefficients for isolated intermediate baryon resonances. It is shown that the spin and parity of the intermediate baryon resonance is reflected in the angular dependence of the anisotropy coefficient. We then compute the anisotropy coefficient including the $N (1520)$ and $N (1440)$ resonances, which are essential at the collision energy of the recent data obtained by the HADES collaboration on this reaction. We conclude that the anisotropy coefficient provides useful constraints for unravelling the resonance contributions to this process.
↳ hep-phnucl-thPLB(2017)·19 citations
10
What do we know about neutrinoless double-beta decay nuclear matrix elements?
J. Menéndez🇯🇵
The detection of neutrinoless double-beta decay will establish the Majorana nature of neutrinos. In addition, if the nuclear matrix elements of this process are reliably known, the experimental lifetime will provide precious information about the absolute neutrino masses and hierarchy. I review the status of nuclear structure calculations for neutrinoless double-beta decay matrix elements, and discuss some key issues to be addressed in order to meet the demand for accurate nuclear matrix elements.
↳ hep-phhep-exnucl-exnucl-th7 citations
11
Shear Viscosity of Turbulent Chiral Plasma
Avdhesh Kumar🇮🇳 · Jitesh R. Bhatt🇮🇳 · Amita Das🇮🇳 · P. K. Kaw🇮🇳
It is well known that the difference between the chemical potentials of left-handed and right-handed particles in a parity violating (chiral) plasma can lead to an instability. We show that the chiral instability may drive turbulent transport. Further we estimate the anomalous viscosity of chiral plasma arising from the enhanced collisionality due to turbulence.
↳ hep-phnucl-th1 citation

Affiliations

first authorsco-authorsvia INSPIRE