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Nuclear Theory·nucl-th

Friday·March 17, 2017

5 papers—4 primary·1 cross-listed

All5Primary4Cross-lists1
  1. 01

    meson mass and decay width in nuclear matter and nuclei

    J.J. Cobos-Martínez🇧🇷 · K. Tsushima🇧🇷 · G. Krein🇧🇷 · A.W.Thomas🇦🇺

    The mass and decay width of the meson in cold nuclear matter are computed in an effective Lagrangian approach. The medium dependence of these properties are obtained by evaluating kaon-antikaon loop contributions to the self-energy, employing the medium-modified kaon masses, calculated using the quark-meson coupling model. The loop integral is regularized with a dipole form factor, and the sensitivity of the results to the choice of cutoff mass in the form factor is investigated. At normal nuclear matter density we find a downward shift of the mass by a few percent, while the decay width is enhanced by an order of magnitude. For a large variation of the cutoff mass parameter, the results for the mass and the decay width turn out to vary very little. Our results support results in the literature which suggest that one should observe a small downward mass shift and a large broadening of the decay width. In order to explore the possibility of studying the binding and absorption of mesons in nuclei, we also present the single-particle binding energies and half-widths of -nucleus bound states for some selected nuclei.

    nucl-thhep-exhep-phnucl-exPLB(2017)·48 citations
  2. 02

    High-quality two-nucleon potentials up to fifth order of the chiral expansion

    D. R. Entem🇪🇸 · R. Machleidt🇺🇸 · Y. Nosyk🇺🇸

    We present NN potentials through five orders of chiral effective field theory ranging from leading order (LO) to next-to-next-to-next-to-next-to-leading order (N4LO). The construction may be perceived as consistent in the sense that the same power counting scheme as well as the same cutoff procedures are applied in all orders. Moreover, the long-range parts of these potentials are fixed by the very accurate pi-N LECs as determined in the Roy-Steiner equations analysis by Hoferichter, Ruiz de Elvira and coworkers. In fact, the uncertainties of these LECs are so small that a variation within the errors leads to effects that are essentially negligible, reducing the error budget of predictions considerably. The NN potentials are fit to the world NN data below pion-production threshold of the year of 2016. The potential of the highest order (N4LO) reproduces the world NN data with the outstanding chi^2/datum of 1.15, which is the highest precision ever accomplished for any chiral NN potential to date. The NN potentials presented may serve as a solid basis for systematic ab initio calculations of nuclear structure and reactions that allow for a comprehensive error analysis. In particular, the consistent order by order development of the potentials will make possible a reliable determination of the truncation error at each order. Our family of potentials is non-local and, generally, of soft character. This feature is reflected in the fact that the predictions for the triton binding energy (from two-body forces only) converges to about 8.1 MeV at the highest orders. This leaves room for three-nucleon-force contributions of moderate size.

    nucl-thnucl-exPRC(2017)·415 citations
  3. 03

    Open-Shell Nuclei from No-Core Shell Model with Perturbative Improvement

    Alexander Tichai🇫🇷 · Eskendr Gebrerufael🇩🇪 · Klaus Vobig🇩🇪 · Robert Roth🇩🇪

    We introduce a hybrid many-body approach that combines the flexibility of the No-Core Shell Model (NCSM) with the efficiency of Multi-Configurational Perturbation Theory (MCPT) to compute ground- and excited-state energies in arbitrary open-shell nuclei in large model spaces. The NCSM in small model spaces is used to define a multi-determinantal reference state that contains the most important multi-particle multi-hole correlations and a subsequent second-order MCPT correction is used to capture additional correlation effects from a large model space. We apply this new ab initio approach for the calculation of ground-state and excitation energies of even and odd-mass carbon, oxygen, and fluorine isotopes and compare to large-scale NCSM calculations that are computationally much more expensive.

    nucl-thPLB(2018)·48 citations
  4. 04

    Spreading widths of giant resonances in spherical nuclei: damped transient response

    A. P. Severyukhin · S. Åberg · N. N. Arsenyev · R. G. Nazmitdinov

    We propose the universal approach to describe spreading widths of monopole, dipole and quadrupole giant resonances in heavy and superheavy spherical nuclei. Our approach is based on the ideas of the random matrix distribution of the coupling between one-phonon and two-phonon states generated in the random phase approximation. We use the Skyrme interaction SLy4 as our model Hamiltonian to create a single-particle spectrum and to analyze excited states of the doubly magic nuclei Sn, Pb and 126. Our results demonstrate that the universal approach enables to describe gross structure of the spreading widths of the considered giant resonances.

    nucl-thPRC(2017)·26 citations

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first authorsco-authorsvia INSPIRE