PaperPanorama

Nuclear Theory·nucl-th

Friday·May 18, 2018

5 papers3 primary·2 cross-listed

  1. 01

    [Submitted on 16 May 2018]

    Evolution of shell structure in exotic nuclei

    Takaharu Otsuka🇯🇵 · Alexandra Gade🇺🇸 · Olivier Sorlin🇫🇷 · Toshio Suzuki🇯🇵 · Yutaka Utsuno🇯🇵

    The atomic nucleus is a quantum many-body system whose constituent nucleons (protons and neutrons) are subject to complex nucleon-nucleon interactions that include spin- and isospin-dependent components. For stable nuclei, already several decades ago, emerging seemingly regular patterns in some observables could be described successfully within a shell-model picture that results in particularly stable nuclei at certain magic fillings of the shells with protons and/or neutrons: N,Z = 8, 20, 28, 50, 82, 126. However, in short-lived, so-called exotic nuclei or rare isotopes, characterized by a large N/Z asymmetry and located far away from the valley of beta stability on the nuclear chart, these magic numbers, viewed through observables, were shown to change. These changes in the regime of exotic nuclei offer an unprecedented view at the roles of the various components of the nuclear force when theoretical descriptions are confronted with experimental data on exotic nuclei where certain effects are enhanced. This article reviews the driving forces behind shell evolution from a theoretical point of view and connects this to experimental signatures.

    Comments:
    69 pages, 70 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1805.06501 [pdf]
    RMP(2020)·434 citations
  2. 02

    [Submitted on 16 May 2018]

    Temperature Dependence of the Neutron Lifespan

    Cheng Tao Yang🇺🇸 · Jeremiah Birrell🇺🇸 · Johann Rafelski (Arizona)🇺🇸

    Current precision big bang nucleosynthesis (BBN) studies motivate us to revisit the neutron lifespan in the plasma medium of the early universe. The mechanism we explore is the Fermi-blocking of decay electrons and neutrinos by plasma. As result, neutrons live longer and we find a significant 6.4\% modification of neutron abundance in the BBN era arising from in plasma modification of the neutron lifetime. This effect can influence the final abundances of the light elements in BBN.

    Comments:
    4 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Plasma Physics (physics.plasm-ph)
    arXiv:
    1805.06543 [pdf]
    3 citations
  3. 03

    [Submitted on 17 May 2018]

    Chiral symmetry restoration by parity doubling and the structure of neutron stars

    Michał Marczenko🇵🇱 · David Blaschke🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱

    We investigate the equation of state for a recently developed hybrid quark-meson-nucleon model under neutron star conditions of equilibrium and charge neutrality. The model has the characteristic feature that at increasing baryon density chiral symmetry is restored in a first order transition within the hadronic phase by lifting the mass splitting between chiral partner states, before quark deconfinement takes place. Most important for this study are the nucleon (neutron, proton) and states. We present three sets for the two free parameters which result in compact star mass-radius relations in accordance with modern constraints on the mass from PSR~J0437-4715 and on the compactness from GW170817. We also consider the threshold for the direct URCA process for which a new relationship is given and suggest as an additional constraint on the parameter choice of the model that this process shall become operative at best for stars with masses above the range for binary radio pulsars, .

    Comments:
    version accepted for publication in Phys. Rev. D
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1805.06886 [pdf]
    PRD(2018)·67 citations

Affiliations

first authorsco-authorsvia INSPIRE