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Nuclear Theory·nucl-th

Tuesday·July 2, 2019

7 papers—5 primary·2 cross-listed

All7Primary5Cross-lists2
  1. 01

    [Submitted on 28 Jun 2019]

    Confinement in Nuclei and the Expanding Proton

    Gerald A. Miller🇺🇸

    High-precision knowledge of electromagnetic form factors of nuclei is a subject of much current experimental and theoretical activity in nuclear and atomic physics. Such precision mandates that effects of the non-zero spatial extent of the constituent nucleons be handled in a manner that goes beyond the usual impulse approximation. A series of simple, Poincare-invariant, composite-proton models that respect the Ward-Takahashi identity and in which quarks are confined are used to study the validity of this approximation. The result of all of the models is a general theorem showing that medium modification of proton structure must occur. Combining this result with lattice QCD calculations leads to a conclusion that a bound proton must be larger than a free one.

    Comments:
    7 pages 2 figures. This version adds references and makes improvements
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1907.00110 [pdf]
    PRL(2019)·14 citations
  2. 02

    [Submitted on 29 Jun 2019]

    Compact pentaquark states predicted by a quark model

    Qi Meng🇨🇳 · Emiko Hiyama🇯🇵 · Kadir Utku Can🇯🇵 · Philipp Gubler🇯🇵 · Makoto Oka🇯🇵 · Atsushi Hosaka🇯🇵 · Hongshi Zong🇨🇳

    Several compact pentaquark resonances are predicted in a potential quark model. The Hamiltonian is the best available one, which reproduces the masses of the low-lying charmed and strange hadrons well. Full five-body calculations are carried out by the use of the Gaussian expansion method, and the relevant baryon-meson thresholds are taken into account explicitly. Employing the real scaling method, we predict four sharp resonances, ( MeV, MeV), (5645 MeV, 30 MeV), (5670 MeV, 50 MeV), and (5360 MeV, 80 MeV). These are the candidates of compact pentaquark resonance states from the current best quark model, which should be confirmed either by experiments or lattice QCD calculations.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1907.00144 [pdf]
    PLB(2019)·30 citations
  3. 03

    [Submitted on 30 Jun 2019]

    Low Energy Magnetic Radiation (LEMAR ) of Warm Nuclei

    S. Frauendorf · B. A. Brown · R. Schwengner

    The enhancement observed below 2 MeV in the radiative strength function of nuclei near closed shells is explained by shell model calculations as M1 transitions between excited states. In the open-shell a change to a bimodal structure composed of the zero energy spike and a scissors resonance is found. The features are caused by realignment of high-j orbitals.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1907.00398 [pdf]
    Proceedings of the 6th International Conf…·1 citation
  4. 04

    [Submitted on 1 Jul 2019]

    Pseudo-spin symmetry restoration and the in-medium balance between nuclear attractive and repulsive interactions

    Jing Geng · Jia Jie Li · Wen Hui Long · Yi Fei Niu · Shi Yao Chang

    The mechanism that restores the pseudo-spin symmetry (PSS) are investigated under the relativistic Hartree-Fock (RHF) approach, by focusing on the in-medium balance between nuclear attractive and repulsive interactions. It is illustrated that the modelings of both the equilibrium of nuclear dynamics and the in-medium effects can be essentially changed by the -tensor coupling that play the role almost fully via the Fock terms, from which the model discrepancy on the PSS restoration is verified. Specifically, the largely different density-dependent behaviors of the isoscalar coupling strengths and , deduced from the parametrization of the RHF Lagrangian PKA1, play an essential role in restoring the PSS of the high- pseudo-spin doublets around the Fermi levels. Qualitatively, a guidance is provided for the modelings of both the equilibrium of nuclear dynamics and the in-medium effects via the PSS restoration.

    Comments:
    3 figures and 2 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1907.00597 [pdf]
    PRC(2019)·30 citations
  5. 05

    [Submitted on 1 Jul 2019]

    Fission modes in fermium isotopes with Brownian shape-motion model

    M. Albertsson · B.G. Carlsson · T. Døssing · P. Möller · J. Randrup · S. Åberg

    Fission-fragment mass and total-kinetic-energy distributions following fission of the fermium isotopes at low excitation energy have been calculated using the Brownian shape-motion model. A transition from asymmetric fission in to symmetric fission in is obtained. The total-kinetic-energy distributions for the three isotopes show radically different behaviour due to varying contributions from different fission modes, with a double-humped distribution for .

    Comments:
    2 pages, 3 figures, Contribution to the Proceedings of the IV International Conference on Nuclear Structure and Dynamics (NSD2019), Venice, Italy, 2019
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1907.00804 [pdf]
    EPJ Web Conf.(2019)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE