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Nuclear Theory·nucl-th

Monday·January 2, 2017

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 01

    Nuclear Weak Rates and Detailed Balance in Stellar Conditions

    G. Wendell Misch

    Detailed balance is often invoked in discussions of nuclear weak transitions in astrophysical environments. Satisfaction of detailed balance is rightly touted as a virtue of some methods of computing nuclear transition strengths, but we argue that it need not necessarily be strictly obeyed, especially when the system is far from weak equilibrium. We present the results of shell model calculations of nuclear weak strengths in both charged current and neutral current channels at astrophysical temperatures. Using these strengths to compute some reaction rates, we find that, despite some violation of detailed balance, our method is robust up to high temperature, and we comment on the relationship between detailed balance and weak equilibrium in astrophysical conditions.

    nucl-thastro-ph.HEApJ(2017)·5 citations
  2. 02

    Solving Dirac equations on a 3D lattice with inverse Hamiltonian and spectral methods

    Z.X. Ren🇨🇳 · S.Q. Zhang🇨🇳 · J. Meng🇨🇳

    A new method to solve the Dirac equation on a 3D lattice is proposed, in which the variational collapse problem is avoided by the inverse Hamiltonian method and the fermion doubling problem is avoided by performing spatial derivatives in momentum space with the help of the discrete Fourier transform, i.e., the spectral method. This method is demonstrated in solving the Dirac equation for a given spherical potential in 3D lattice space. In comparison with the results obtained by the shooting method, the differences in single particle energy are smaller than ~MeV, and the densities are almost identical, which demonstrates the high accuracy of the present method. The results obtained by applying this method without any modification to solve the Dirac equations for an axial deformed, non-axial deformed, and octupole deformed potential are provided and discussed.

    nucl-thnucl-exPRC(2017)·61 citations
  3. 03

    Antisymmetrized molecular dynamics studies for exotic clustering phenomena in neutron-rich nuclei

    M. Kimura · T. Suhara · Y. Kanada-En'yo

    We present a review of recent works on clustering phenomena in unstable nuclei studied by antisymmetrized molecular dynamics (AMD). The AMD studies in these decades have uncovered novel types of clustering phenomena brought about by the excess neutrons. Among them, this review focuses on the molecule-like structure of unstable nuclei. One of the earliest discussions on the clustering in unstable nuclei was made for neutron-rich Be and B isotopes. AMD calculations predicted that the ground state clustering is enhanced or reduced depending on the number of excess neutrons. Today, the experiments are confirming this prediction as the change of the proton radii. Behind this enhancement and reduction of the clustering, there are underlying shell effects called molecular- and atomic-orbits. These orbits form covalent and ionic bonding of the clusters analogous to the atomic molecules. It was found that this "molecular-orbit picture" reasonably explains the low-lying spectra of Be isotopes. The molecular-orbit picture is extended to other systems having parity asymmetric cluster cores and to the three cluster systems. O and Ne isotopes are the candidates of the former, while the linear chains in C isotopes are the latter. For both subjects, many intensive studies are now in progress. We also pay a special attention to the observables which are the fingerprint of the clustering. In particular, we focus on the monopole and dipole transitions which are recently regarded as good probe for the clustering. We discuss how they have and will reveal the exotic clustering.

    nucl-thEPJA(2016)·73 citations
  4. 04

    Bohr Hamiltonian for gamma=0 with Davidson Potential

    I.Yigitoglu · M.Gokbulut

    A gamma-rigid solution of the Bohr Hamiltonian is derived for gamma=0 utilizing the Davidson potential in the beta variable. This solution is going to be called X(3)-D. The energy eigenvalues and wave functions are obtained by using an analytic method which has been developed by Nikiforov and Uvarov. BE(2) transition rates are calculated. A variational procedure is applied to energy ratios to determine whether or not the X(3) model is located at the critical point between spherical and deformed nuclei.

    nucl-thEur.Phys.J.Plus(2017)·4 citations
  5. 05

    Hybrid Stars in the Framework of different NJL Models

    G. A. Contrera🇦🇷 · M. Orsaria🇺🇸 · I. F. Ranea-Sandoval🇦🇷 · F. Weber🇺🇸

    We compute models for the equation of state (EoS) of the matter in the cores of hybrid stars. Hadronic matter is treated in the non-linear relativistic mean-field approximation, and quark matter is modeled by three-flavor local and non-local NambuJona-Lasinio (NJL) models with repulsive vector interactions. The transition from hadronic to quark matter is constructed by considering either a soft phase transition (Gibbs construction) or a sharp phase transition (Maxwell construction). We find that high-mass neutron stars with masses up to may contain a mixed phase with hadrons and quarks in their cores, if global charge conservation is imposed via the Gibbs conditions. However, if the Maxwell conditions is considered, the appearance of a pure quark matter core either destabilizes the star immediately (commonly for non-local NJL models) or leads to a very short hybrid star branch in the mass-radius relation (generally for local NJL models).

    nucl-thastro-ph.HEastro-ph.SRhep-phInt.J.Mod.Phys.Conf.Ser.(2017)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE