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Nuclear Theory·nucl-th

Friday·October 6, 2017

8 papers—3 primary·5 cross-listed

All8Primary3Cross-lists5
  1. 01

    [Submitted on 4 Oct 2017]

    An empirical model of low-energy np scattering: Insights beyond ERT

    R. W. Hackenburg

    A model is presented of s-wave np elastic scattering as proceeding through an intermediate, off-shell dibaryon d*, with corrections to the npd vertex and d* propagator. The model relies on plausible conjectures and hypotheses to match identically the form of the simple amplitude given by the shape-independent effective range theory (SI ERT), which exactly describes the extant np elastic data (within errors) to at least 3 MeV. The result provides insight into the mechanisms involved in np scattering, which go beyond what ERT can reveal because ERT is a product of wave-mechanics and is therefore generally independent of mechanism. For example, in this model, the signs of the triplet and singlet scattering lengths are determined by the (opposite) spatial symmetries of the triplet and singlet np wavefunctions and pion exchange in the vertex corrections.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1710.01803 [pdf]
    0 citations
  2. 02

    [Submitted on 4 Oct 2017]

    Application of superconducting-superfluid magnetohydrodynamics to nuclear "pasta" in neutron stars

    D. N. Kobyakov

    A mixture of superconducting and superfluid nuclear liquids of protons coupled to the ultrarelativistic electron gas, and neutrons is considered. In the magnetohydrodynamic (MHD) approximation, the energy-momentum (stress) tensor is derived, and the entrainment contribution is found in the explicit form. It is shown that this contribution generates a force density, when a superfluid velocity lag and the magnetic field are simultaneously present. This force may be important in the nuclear "pasta" phase in neutron stars, if the proton and neutron Cooper pairing in the pasta phase is taken into account. It is found that if the liquid-crystalline matter of the pasta phase is superfluid and superconducting, then magnitude of the forces acting upon element of matter at typical magnetic field and the superfluid velocity lag, under certain conditions may become large enough to induce a critical stress in the neutron star crust. As an application, the necessary conditions for triggering of a starquake are found in the pasta phase of neutron stars, assuming that the nuclei are flat slabs in parallel magnetic field. The present model includes two independent local parameters: the superfluid velocity lag and the magnetic field. Possible links between the entrainment force and the magnetar starquake triggering mechanism, and some open problems are discussed.

    Comments:
    Accepted version for Physical Review C. 8 pages, no figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1710.02018 [pdf]
    PRC(2018)·15 citations
  3. 03

    [Submitted on 5 Oct 2017]

    Antibaryon interactions with the nuclear medium

    Jaroslava Hrtánková🇨🇿 · Jiří Mareš

    This contribution deals with our recent study of antibaryon interactions with the nuclear medium within the relativistic mean-field approach using antibaryon coupling constants consistent with available experimental data. We performed calculations of () bound states in selected nuclei. Due to the lack of information on the in-medium antihyperon annihilation near threshold only the absorption was considered. It was described by the imaginary part of a phenomenological optical potential fitted to -atom data. The annihilation was treated dynamically, taking into account explicitly the reduced phase space for annihilation products in the nuclear medium, as well as the compressed nuclear density due to the antiproton. The energy available for the annihilation products was evaluated self-consistently, considering additional energy shift due to particle momenta in the -nucleus system. Corresponding widths were significantly reduced, however, they still remain sizable. Next, the -nucleus interaction was constructed using the latest version of the Paris potential. Related scattering amplitudes were used to define the complex optical potential in the nuclear medium. The resulting binding energies are about 10% smaller and widths about 20% larger than those obtained with the phenomenological approach.

    Comments:
    8 pages, 6 figures, proceedings of the 26th International Nuclear Physics Conference, Adelaide, Australia, 11-16 September, 2016
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1710.02045 [pdf]
    PoS(2017)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE