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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
  6. 06

    [Submitted on 28 Jun 2019] (cross-list from hep-ph)

    Metastable Nuclear Isomers as Dark Matter Accelerators

    Maxim Pospelov🇨🇦 · Surjeet Rajendran🇺🇸 · Harikrishnan Ramani🇺🇸

    Inelastic dark matter and strongly interacting dark matter are poorly constrained by direct detection experiments since they both require the scattering event to deliver energy from the nucleus into the dark matter in order to have observable effects. We propose to test these scenarios by searching for the collisional de-excitation of meta-stable nuclear isomers by the dark matter particles. The longevity of these isomers is related to a strong suppression of - and -transitions, typically inhibited by a large difference in the angular momentum for the nuclear transition. The collisional de-excitation by dark matter is possible since heavy dark matter particles can have a momentum exchange with the nucleus comparable to the inverse nuclear size, hence lifting tremendous angular momentum suppression of the nuclear transition. This de-excitation can be observed either by searching for the direct effects of the decaying isomer, or through the re-scattering or decay of excited dark matter states in a nearby conventional dark matter detector setup. Existing nuclear isomer sources such as naturally occurring Ta, Ba produced in decaying Cesium in nuclear waste, Lu from medical waste, and Hf from the Department of Energy storage can be combined with current dark matter detector technology to search for this class of dark matter.

    Comments:
    13 pages, 6 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1907.00011 [pdf]
    PRD(2020)·48 citations
  7. 07

    [Submitted on 1 Jul 2019] (cross-list from nucl-ex)

    PCN calculations for Z=111 to Z=118

    Walter Loveland · Liangyu Yao

    In previous publications, we presented evidence for the importance of spin in determining capture and evaporation residue cross sections in the synthesis of heavy nuclei. We extend the previous calculations which dealt with nuclei where ZCN is less than 110 to the region of ZCN = 111-118. We deduce a new systematics of the fusion probability for these reactions

    Comments:
    7 pages, 3 figures, presented at the CNR*18 conference
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1907.00936 [pdf]
    Springer Proc.Phys.(2021)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE