PaperPanorama
FAQ

Nuclear Theory·nucl-th

Wednesday·March 28, 2018

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 01

    The nuclear symmetry energy and the breaking of the isospin symmetry: how do they reconcile with each other?

    X. Roca-Maza (1) · G. Colo' (1) · H. Sagawa (2) ((1) Universita' degli Studi and INFN, Via Celoria 16, 20133 Milano, Italy (2) RIKEN Nishina Center, Wako 351-0198, Japan and University of Aizu, Aizu-Wakamatsu, Fukushima 965-8560, Japan)

    We analyze and propose a solution to the apparent inconsistency between our current knowledge of the Equation of State of asymmetric nuclear matter, the energy of the Isobaric Analog State (IAS) in a heavy nucleus such as 208Pb, and the isospin symmetry breaking forces in the nuclear medium. This is achieved by performing state-of-the-art Hartree-Fock plus Random Phase Approximation calculations of the IAS that include all isospin symmetry breaking contributions. To this aim, we propose a new effective interaction that is successful in reproducing the IAS excitation energy without compromising other properties of finite nuclei.

    nucl-thnucl-exPRL(2018)·53 citations
  2. 02

    The -decay nuclear matrix element for light and heavy neutrino mass mechanisms from deformed QRPA cacluations for Ge, Se, Te, Xe and Nd with isospin restoration

    Dong-Liang Fang🇨🇳 · Amand Faessler🇩🇪 · Fedor Šimkovic🇷🇺

    In this work, with restored isospin symmetry, we evaluated the neutrinoless double beta decay nuclear matrix elements for Ge, Se, Te, Xe and Nd for both the light and heavy neutrino mass mechanisms using the deformed QRPA approach with realistic forces. We give detailed decompositions of the nuclear matrix elements over different intermediate states and nucleon pairs, and discuss how these decompositions are affected by the model space truncations. Compared to the spherical calculations, our results show reductions from to about of the nuclear matrix elements for the calculated isotopes mainly due to the presence of BCS overlap factor between the initial and final ground states. The comparison between different nucleon-nucleon forces with corresponding Short-Range-Correlations (src) shows, that the choice of the NN force gives roughly deviations for light exchange neutrino mechanism and much larger deviations for the heavy neutrino exchange mechanism.

    nucl-thhep-phPRC(2018)·118 citations
  3. 03

    Low-lying states in even Gd isotopes studied with five-dimensional collective Hamiltonian based on covariant density functional theory

    Z. Shi · Q. B. Chen · S. Q. Zhang

    Five-dimensional collective Hamiltonian based on the covariant density functional theory has been applied to study the the low-lying states of even-even Gd isotopes. The shape evolution from Gd to Gd is presented. The experimental energy spectra and intraband transition probabilities for the Gd isotopes are reproduced by the present calculations. The relative ratios in present calculations are also compared with the available interacting boson model results and experimental data. It is found that the occupations of neutron orbital result in the well-deformed prolate shape, and are essential for Gd isotopes.

    nucl-thEPJA(2018)·11 citations
  4. 04

    Nucleon internal degrees of freedom and the uniqueness of the Gamow-Teller state

    N. Auerbach

    The Gamow-Teller strength in nuclei can be strongly affected by the internal degrees of freedom of the nucleon. It is demonstrated that this feature is unique to the Gamow-Teller. Excitation modes that involve spatial degrees of freedom are much less influenced by the internal excitation of nucleons. The fact that the observed Gamow-Teller strength is quenched by 30-40 percent in all nuclei suggests that indeed this is due to the nucleon excitation in nuclei.

    nucl-thnucl-ex1 citation
  5. 05

    Three-nucleon force in chiral EFT with explicit degrees of freedom: Longest-range contributions at fourth order

    H. Krebs🇩🇪 · A. M. Gasparyan🇩🇪 · E. Epelbaum🇩🇪

    We analyze the longest-range two-pion exchange contributions to the three-nucleon force at leading-loop order in the framework of heavy-baryon chiral effective field theory with explicit degrees of freedom. All relevant low-energy constants which appear in the calculation are determined from pion-nucleon scattering. Comparing our results with the ones obtained in the -less theory at N4LO, we find effects of the isobar for this particular topology to be rather well represented in terms of resonance saturation of various low-energy constants in the -less approach.

    nucl-thPRC(2018)·47 citations
  6. 06

    Effect of thresholds on the width of three-body resonances

    H. Garcilazo · A. Valcarce

    It has been recently reported an intriguing theoretical result of a narrow three-body resonance with a large available phase space. The resonance was reported in the system near the threshold, having a very small width in spite of the open channel lying around 23 MeV below the channel. We use first-order perturbation theory as a plausible argument to explain this behavior. We apply our result to realistic local interactions. Other systems involving several thresholds are likely to follow the same behavior.

    nucl-thhep-phPLB(2017)·5 citations
  7. 07

    New algorithm in the variation after projection calculations for non-yrast nuclear states

    Jia-Qi Wang · Zao-Chun Gao · Ying-Jun Ma · Y.S. Chen

    We present a novel and simple algorithm in the variation after projection (VAP) approach for the non-yrast nuclear states. It is for the first time that the yrast state and non-yrast states can be varied on the same footing. The orthogonality among the calculated states is automatically fulfilled by solving the Hill-Wheeler equation. This avoids the complexity of the frequently used Gram-Schmidt orthogonalization, as adopted by the excited VAMPIR method. Thanks to the Cauchy's interlacing theorem in the matrix theory, the sum of the calculated lowest projected energies with the same quantum numbers can be safely minimized. Once such minimization is converged, all the calculated energies and the corresponding states can be obtained, simultaneously. The present VAP calculations are performed with time-odd Hartree-Fock Slater determinants. It is shown that the calculated VAP energies (both yrast and non-yrast) are very close to the corresponding ones from the full shell model calculations. It looks the present algorithm is not limited to the VAP, but should be universal, i.e., one can do the variation with different forms of the many-body wavefunctions to calculate the excited states in different quantum many-body systems.

    nucl-thPRC(2018)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE