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Nuclear Theory·nucl-th

Monday·June 3, 2019

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 01

    [Submitted on 31 May 2019]

    Perey-effect in Continuum-Discretized Coupled-Channel description of reactions

    M. Gómez-Ramos · N. K. Timofeyuk

    The Perey-effect in two-body channels of reactions has been known for a long time. It arises when the nonlocal two-body deuteron-target and/or proton-target problem is approximated by a local one, manifesting itself in a reduction of the scattering channel wave functions in the nuclear interior. However, the reaction mechanism requires explicit accounting for three-body dynamics involving the target and the neutron and proton in the deuteron. Treating nonlocality of the nucleon-target interactions within a three-body context requires significant effort and demands going beyond the widely-used adiabatic approximation, which can be done using a continuum-discretized coupled-channel (CDCC) method. However, the inclusion of nonlocal interactions into the CDCC description of reactions has not been developed yet. Here, we point out that, similarly to the two-body nonlocal case, nonlocality in a three-body channel can be accounted for by introducing the Perey factors. We explain this procedure and present the first CDCC calculations to our knowledge including the Perey-effect.

    Comments:
    13 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1905.13451 [pdf]
    J.Phys.G(2019)·3 citations
  2. 02

    [Submitted on 31 May 2019]

    Topological defects at the boundary of neutron superfluids in neutron stars

    Shigehiro Yasui🇯🇵 · Chandrasekhar Chatterjee🇯🇵 · Muneto Nitta🇯🇵

    We study surface effects of neutron superfluids in neutron stars. superfluids are in uniaxial nematic (UN), D biaxial nematic (BN), or D BN phase, depending on the strength of magnetic fields from small to large. We suppose a neutron superfluid in a ball with a spherical boundary. Adopting a suitable boundary condition for condensates, we solve the Ginzburg-Landau equation to find several surface properties for the neutron superfluid. First, the phase on the surface can be different from that of the bulk, and symmetry restoration or breaking occurs in general on the surface. Second, the distribution of the surface energy density has an anisotropy depending on the polar angle in the sphere, which may lead to the deformation of the geometrical shape of the surface. Third, the order parameter manifold induced on the surface, which is described by two-dimensional vector fields induced on the surface from the condensates, allows topological defects (vortices) on the surface, and there must exist such defects even in the ground state thanks to the Poincaré-Hopf theorem: although the numbers of the vortices and antivortices depend on the bulk phases, the difference between them is topologically invariant (the Euler number ) irrespective of the bulk phases. These vortices, which are not extended to the bulk, are called boojums in the context of liquid crystals and helium-3 superfluids. The surface properties of the neutron superfluid found in this paper may provide us useful information to study neutron stars.

    Comments:
    30 pages, 11 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Superconductivity (cond-mat.supr-con); High Energy Physics — Theory (hep-th)
    arXiv:
    1905.13666 [pdf]
    PRC(2020)·16 citations

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first authorsco-authorsvia INSPIRE