PaperPanorama
FAQ

Nuclear Theory·nucl-th

Wednesday·January 1, 2020

12 papers—3 primary·9 cross-listed

All12Primary3Cross-lists9
  1. 01

    [Submitted on 28 Dec 2019]

    Strong-coupling effects of pairing fluctuations, and Anderson-Bogoliubov mode in neutron S superfluids in neutron stars

    Daisuke Inotani🇯🇵 · Shigehiro Yasui🇯🇵 · Muneto Nitta🇯🇵

    We investigate effects of thermal and quantum fluctuations of the superfluid order parameter in superfluids in neutron stars. We construct a separable potential to reproduce the phase shift reconstructed by using the partial wave analysis from nucleon scattering data. We include superfluid fluctuations within a strong-coupling approximation developed by Nozières and Schmitt-Rink and determine self-consistently the superfluid order parameter as well as the chemical potential. We show that the quantum depletion, which gives a fraction of noncondensed neutrons at zero temperature due to quantum pairing fluctuations, plays an important role not only near the critical temperature from superfluid states to normal states but also at zero temperature. We derive the dispersion relation of Anderson-Bogoliubov modes associated with phase fluctuations, and show also that there is a nonzero fraction of noncondensed components in the neutron number as a result of the strong-coupling effect. Our results indicate that superfluid fluctuations are important for thermodynamic properties in neutron stars.

    Comments:
    13 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas)
    arXiv:
    1912.12420 [pdf]
    PRC(2020)·7 citations
  2. 02

    [Submitted on 28 Dec 2019]

    Hadron properties in a nuclear medium and effective nuclear force from quarks: the quark-meson coupling model

    K. Tsushima🇧🇷

    We give a short review of the quark-meson coupling (QMC) model, the quark-based model of finite nuclei and hadron interactions in a nuclear medium, highlighting on the relationship with the Skyrme effective nuclear forces. The model is based on a mean field description of nonoverlapping nucleon MIT bags bound by the self-consistent exchange of Lorentz-scalar-isoscalar, Lorentz-vector-isoscalar, and Lorentz-vector-isovector meson fields directly coupled to the light quarks up and down. In conventional nuclear physics the Skyrme effective forces are very popular, but, there is no satisfactory interpretation of the parameters appearing in the Skyrme forces. Comparing a many-body Hamiltonian generated by the QMC model in the zero-range limit with that of the Skyrme force, it is possible to obtain a remarkable agreement between the Skyrme force and the QMC effective interaction. Furthermore, it is shown that 3-body and higher order N-body forces are naturally included in the QMC-generated effective interaction.

    Comments:
    8 pages, 3 figures, published in AAPPS (Association of Asia Pacific Physical Sciences) Bulletin, DECEMBER Vol. 29 No. 6, APCTP Section-2, pages 37 - 45 (2019). arXiv admin note: substantial text overlap with arXiv:1810.09260
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1912.12461 [pdf]
    AAPPS (Association of Asia Pacific Physic…·3 citations
  3. 03

    [Submitted on 29 Dec 2019]

    Many-body correlations in nuclear superfluidity

    Elena Litvinova🇺🇸 · Peter Schuck🇫🇷

    The two-fermion two-point correlation function in the pairing channel is discussed in the equation of motion framework. Starting from the bare two-fermion interaction, we derive the equation of motion for the two-fermion pair propagator in a strongly-correlated medium. The resulting equation is of the Dyson type with the kernel having a static and a one frequency dependent components and, thus, can be regarded as Dyson Bethe-Salpeter equation (Dyson-BSE). The many-body hierarchy generated by the dynamical interaction kernel is truncated on the level of two-body correlation functions, thus neglecting the explicit three-body and higher-rank correlations. The truncation is performed via a cluster expansion of the intermediate three-particle-one-hole correlation function irreducible in the particle-particle channel, that leads to the coupling between single fermions and emergent collective modes of excitation. The latter couplings are, thus, derived in terms of the exact mapping of the in-medium two-fermion correlation functions onto the domain of bosonic quasibound states (phonons) without introducing new parameters. The approach is applied to calculations of the pairing gaps in medium-mass nuclear systems, that include calcium, nickel and tin isotopic chains.

    Comments:
    Article: 14 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1912.12585 [pdf]
    PRC(2020)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE