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Nuclear Theory·nucl-th

Wednesday·December 20, 2017

8 papers—3 primary·5 cross-listed

All8Primary3Cross-lists5
  1. 01

    [Submitted on 19 Dec 2017]

    New Gogny interaction suitable for astrophysical applications

    C. Gonzalez-Boquera · M. Centelles · X. Viñas · L. M. Robledo

    The D1 family of parametrizations of the Gogny interaction commonly suffers from a rather soft neutron matter equation of state that leads to maximal masses of neutron stars well below the observational value of two solar masses. We propose a reparametrization scheme that preserves the good properties of the Gogny force but allows one to tune the density dependence of the symmetry energy, which, in turn, modifies the predictions for the maximum stellar mass. The scheme works well for D1M, and leads to a new parameter set, dubbed D1M*. In the neutron-star domain, D1M* predicts a maximal mass of two solar masses and global properties of the star in harmony with those obtained with the SLy4 Skyrme interaction. By means of a set of selected calculations in finite nuclei, we check that D1M* performs comparably well to D1M in several aspects of nuclear structure in nuclei.

    Comments:
    6 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    1712.06735 [pdf]
    PLB(2018)·72 citations
  2. 02

    [Submitted on 19 Dec 2017]

    Exotic atoms at extremely high magnetic fields: the case of neutron star atmosphere

    Andrea Fontana · Alessandro Colombi · Pietro Carretta · Alessandro Drago · Paolo Esposito · Paola Gianotti · Carlotta Giusti · Diego Lonardoni · Alessandro Lovato · Vincenzo Lucherini · Francesco Pederiva

    The presence of exotic states of matter in neutron stars (NSs) is currently an open issue in physics. The appearance of muons, kaons, hyperons, and other exotic particles in the inner regions of the NS, favored by energetic considerations, is considered to be an effective mechanism to soften the equation of state (EoS). In the so-called two-families scenario, the softening of the EoS allows for NSs characterized by very small radii, which become unstable and convert into a quark stars (QSs). In the process of conversion of a NS into a QS material can be ablated by neutrinos from the surface of the star. Not only neutron-rich nuclei, but also more exotic material, such as hypernuclei or deconfined quarks, could be ejected into the atmosphere. In the NS atmosphere, atoms like H, He, and C should exist, and attempts to model the NS thermal emission taking into account their presence, with spectra modified by the extreme magnetic fields, have been done. However, exotic atoms, like muonic hydrogen or the so-called Sigmium , could also be present during the conversion process or in its immediate aftermath. At present, analytical expressions of the wave functions and eigenvalues for these atoms have been calculated only for H. In this work, we extend the existing solutions and parametrizations to the exotic atoms and , making some predictions on possible transitions. Their detection in the spectra of NS would provide experimental evidence for the existence of hyperons in the interior of these stars.

    Comments:
    10 pages, 6 figures, proceedings of the "International Conference on Exotic Atoms and Related Topics - EXA2017", Austrian Academy of Sciences, Austria, September 11-15, 2017
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Atomic Physics (physics.atom-ph)
    arXiv:
    1712.06818 [pdf]
    EPJ Web Conf.(2018)·0 citations
  3. 03

    [Submitted on 19 Dec 2017]

    Effects of chiral three-nucleon forces on He-nucleus scattering in a wide range of incident energies

    Masakazu Toyokawa · Masanobu Yahiro · Takuma Matsumoto · Michio Kohno

    It is a current important subject to clarify properties of chiral three-nucleon forces (3NFs) not only in nuclear matter but also in scattering between finite-size nuclei. Particularly for the elastic scattering, this study has just started and the properties are not understood in a wide range of incident energies (). We investigate basic properties of chiral 3NFs in nuclear matter with positive energies by using the Brueckner-Hartree-Fock method with chiral two-nucleon forces of NLO and 3NFs of NNLO, and analyze effects of chiral 3NFs on He elastic scattering from targets Pb, Ni and Ca over a wide range of MeV by using the -matrix folding model, where is the mass number of projectile. In symmetric nuclear matter with positive energies, chiral 3NFs make the single-particle potential less attractive and more absorptive. The effects mainly come from the Fujita-Miyazawa 2-exchange 3NF and slightly become larger as increases. These effects persist in the optical potentials of He scattering. As for the differential cross sections of He scattering, chiral-3NF effects are large in MeV and improve the agreement of the theoretical results with the measured ones. Particularly in MeV, the folding model reproduces measured differential cross sections pretty well. Cutoff () dependence is investigated for both nuclear matter and He scattering by considering two cases of and MeV. The uncertainty coming from the dependence is smaller than chiral-3NF effects even at MeV.

    Comments:
    14 pages, 15 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1712.07033 [pdf]
    PTEP(2018)·27 citations

Affiliations

first authorsco-authorsvia INSPIRE