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Nuclear Theory·nucl-th

Monday·April 1, 2019

8 papers—3 primary·5 cross-listed

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  1. 01

    [Submitted on 28 Mar 2019]

    The Schwinger Scattering of Twisted Neutrons by Nuclei

    Andrei V. Afanasev · D.V. Karlovets · V.G. Serbo

    Thanks to J.~Schwinger, the process of elastic scattering of neutrons by nuclei is known to depend on the interference between a nuclear amplitude and an electromagnetic one for small scattering angles, resulting in spin asymmetries of a cross section or in polarization of the scattered neutrons. While this interference depends on the neutron's {\it transverse} polarization and on {\it an imaginary part} of the nuclear amplitude, this conclusion holds only for the incident plane-wave neutrons with a definite momentum. Here we show that this scattering is altered when the twisted neutrons, recently obtained experimentally, are used instead -- that is, neutrons with an orbital angular momentum. For bulk targets, the angular distributions of the scattered neutrons get modified, while scattering of a superposition of states with the different angular momenta also reveals dependence on the longitudinal polarization. For well-localized targets, the observables develop a dependence on the neutron's {\it helicity} and on {\it a real part} of the nuclear amplitude, providing full access to its phase already in the Born approximation. We argue that the corresponding spin asymmetries are measurable at existing neutron facilities. Thus, scattering of the twisted neutrons by nuclei can provide means for quantum tomography of the neutron states and become a useful tool for hadronic studies, low-energy nuclear physics, tests of fundamental symmetries, and neutron optics.

    Comments:
    5 pages, 4 figures; revised version includes an additional figure
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1903.12245 [pdf]
    PRC(2019)·31 citations
  2. 02

    [Submitted on 29 Mar 2019]

    Shape and shell-structure of lighter (N<90) neutron-rich nuclei based on phenomenological Woods-Saxon potential

    Ikuko Hamamoto

    By using a phenomenologically successful Woods-Saxon potential, I study the shape and shell structure of (A) neutron drip line nuclei with 10 \leq N \leq 60, (B) neutron-rich nuclei related to the r- process with 40 \leq N \leq 90, and (C) one-particle spectra in the potential provided by the nucleus 70Fe as a representative of so-called N=40 "island of inversion (IoI)" nuclei. First, the shell structure that is unique in very weakly-bound neutrons is systematically studied, and the approximate neutron number of odd-N nuclei at which spherical (or deformed) halos can be found is pinned down. Second, the difference of the shell structure in r-process nuclei from that in stable nuclei is examined. Third, the similarity and the difference between the shell structure of N=20 IoI nuclei and that of N=40 IoI nuclei are analyzed. As a result of it, it is concluded that in Fe and Cr isotopes the deformation called "N=40 IoI" continuing up to N=50 is unlikely.

    Comments:
    19 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1903.12373 [pdf]
    PRC(2019)·8 citations
  3. 03

    [Submitted on 29 Mar 2019]

    Ab initio short-range-correlation scaling factors from light to medium-mass nuclei

    J. E. Lynn🇩🇪 · D. Lonardoni🇺🇸 · J. Carlson🇺🇸 · J.-W. Chen🇹🇼 · W. Detmold🇺🇸 · S. Gandolfi🇺🇸 · A. Schwenk🇩🇪

    High-energy scattering processes, such as deep inelastic scattering (DIS) and quasielastic (QE) scattering provide a wealth of information about the structure of atomic nuclei. The remarkable discovery of the empirical linear relationship between the slope of the European Muon Collaboration (EMC) effect in DIS and the short-range-correlation (SRC) scaling factors in QE kinematics is naturally explained in terms of scale separation in effective field theory. This explanation has powerful consequences, allowing us to calculate and predict SRC scaling factors from ab initio low-energy nuclear theory. We present ab initio calculations of SRC scaling factors for a nucleus relative to the deuteron and relative to in light and medium-mass nuclei. Our framework further predicts that the EMC effect and SRC scaling factors have minimal or negligible isovector corrections.

    Comments:
    25 pages, 6 figures, 2 tables
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1903.12587 [pdf]
    J.Phys.G(2020)·36 citations

Affiliations

first authorsco-authorsvia INSPIRE