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Nuclear Theory·nucl-th

Tuesday·April 3, 2018

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 01

    [Submitted on 1 Apr 2018]

    Excitation of Th nuclei in laser plasma: the energy and half-life of the low-lying isomeric state

    P.V. Borisyuk · E.V. Chubunova · N.N. Kolachevsky · Yu.Yu. Lebedinskii · O.S. Vasiliev · E.V. Tkalya

    The results of experimental studies of the low-energy isomeric state in the Th nucleus are presented. The work is consisted of several stages. During the first stage Th nuclei were excited with the inverse internal conversion to the low-lying isomeric level in plasma that was formed by laser pulse at the Th-containing target surface. Then thorium ions having excited nuclei were extracted from the plasma by an external electrical field and implanted into thin SiO film grown on a silicon substrate (that is a dielectric material with about 9 eV band-gap). Gamma decay of isomeric nuclei was registered during the second stage by the general methods of the electron spectroscopy after the photon-electron emission from the silicon substrate. Substitution of the photon registration with the electron one allowed us to increase the desired signal by several orders of magnitude and detect the Th nuclei decay. During the third stage the electron spectra from standard Xe VUV source was obtained that allowed determining the energy of photons. In order to prove that the detected signal is caused by isomeric Th nuclei decay a series of experiments was carried. The analysis of electron spectra gives the following results: the energy of the nuclear transition is ~eV, the half-life of the isomeric level in bare nucleus in vacuum is ~s, the reduced probability of the isomeric nuclear transition is .

    Comments:
    11 pages, 11 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex); physics.optics (physics.optics); Plasma Physics (physics.plasm-ph)
    arXiv:
    1804.00299 [pdf]
    12 citations
  2. 02

    [Submitted on 1 Apr 2018]

    A pseudo-conformal equation of state in compact-star matter from topology change and hidden symmetries of QCD

    Yong-Liang Ma🇨🇳 · Hyun Kyu Lee🇰🇷 · Won-Gi Paeng🇰🇷 · Mannque Rho🇫🇷

    We construct a new effective field theory approach to the equation of state (EoS), dubbed pseudo-confomal model "PCM," for nuclear and compact star matter entirely in terms of effective hadron degrees of freedom. The possible transition at (where is the normal nuclear matter density) from hadron degrees of freedom to strongly-coupled quark degrees of freedom, giving rise to a soft-to-hard changeover in the EoS that can accommodate the massive stars observed, is effectuated by the topology change at from skyrmions to half-skyrmions without involving local order-parameter fields. The mechanism exploits possible emergence of hidden scale and local symmetries of QCD at high density, leading to a precocious "pseudo-conformal" sound velocity (in unit of ) for . The resulting prediction signals a drastic departure from standard nuclear many-body theory in the density regime involved in the massive stars. We suggest that the tidal deformability implemented in gravitational waves coming from coalescing neutron stars in LIGO/Virgo-type observations could pin down the location of the topology change density .

    Comments:
    6 pages, 4 figures; revised for submission to journal
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1804.00305 [pdf]
    SCPMA(2019)·24 citations
  3. 03

    [Submitted on 1 Apr 2018]

    The Non-Quenching of in Nuclei and Emergent Scale Symmetry in Dense Baryonic Matter

    Yan-Ling Li🇨🇳 · Yong-Liang Ma🇨🇳 · Mannque Rho🇫🇷

    How the axial coupling constant in nuclear Gamow-Teller transitions described in shell model gets "quenched" to a universal constant close to 1 can be explained by nuclear correlations in Fermi-liquid fixed point theory using a scale-symmetric chiral Lagrangian supplemented with hidden local symmetric vector mesons. Contrary to what one might naively suspect -- and has been discussed in some circles, there is no fundamental quenching at nuclear matter density due to QCD condensates. When the density of many-body systems treated with the same Lagrangian increases beyond the density (where is the normal nuclear matter density) at which skyrmions representing baryons fractionize to half-skyrmions, with the meson driven toward the vector manifestation fixed point and a scalar meson driven to the dilaton-limit fixed point with the nucleons parity-doubled, the dense matter supports the "pseudo-conformal" sound velocity for while the trace of the energy momentum tensor remains non-vanishing. A plausible interpretation is that this signals the emergence of scale symmetry not explicitly present or hidden in QCD in the vacuum. The fundamental constant , unaffected by QCD condensates for , does go to 1 as the dilaton-limit fixed point is approached before arriving at chiral restoration, but it is not directly related to the "quenched " in nuclei which can be explained as a Fermi-liquid fixed point quantity. The mechanism that produces a precocious pseudo-conformal sound velocity is expected to impact on the tidal deformability in gravity waves from coalescing neutron stars.

    Comments:
    Published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1804.00310 [pdf]
    PRC(2018)·11 citations
  4. 04

    [Submitted on 2 Apr 2018]

    Fluctuations in the U(n,f) cross section

    G.F. Bertsch🇺🇸 · David Brown🇺🇸 · E.D. Davis🇺🇸

    We examine the autocorrelation function of the U(n,f) reaction with a view to quantify the presence of intermediate structure in the cross section. Fluctuations due to compound nucleus resonances on the eV energy scale are clearly visible up to keV neutron energies. Structure on the one-keV energy scale is not present as a systematic feature of the correlation function, although it is present in the data covering the region around 20 keV.

    Comments:
    25 pages and 12 figures. To be submitted to Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1804.00364 [pdf]
    PRC(2018)·10 citations
  5. 05

    [Submitted on 2 Apr 2018]

    Microscopic optical potentials including breakup effects for elastic scattering

    Shoya Ogawa · Ryo Horinouchi · Masakazu Toyokawa · Takuma Matsumoto

    We construct a microscopic optical potential including breakup effects for elastic scattering of weakly-binding projectiles within the Glauber model, in which a nucleon-nucleus potential is derived by the -matrix folding model. The derived microscopic optical potential is referred to as the eikonal potential. For scattering, the calculation with the eikonal potential reasonably reproduces the result with an exact calculation estimated by the continuum-discretized coupled-channels method. As the properties of the eikonal potential, the inaccuracy of the eikonal approximation used in the Glauber model is partially excluded. We also analyse the He scattering from C with the eikonal potential and show its applicability to the scattering with many-body projectiles.

    Comments:
    7 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1804.00416 [pdf]
    PTEP(2019)·1 citation
  6. 06

    [Submitted on 2 Apr 2018]

    Medium-induced gluon emission via transverse and longitudinal scattering in dense nuclear matter

    Le Zhang🇨🇳 · De-Fu Hou🇨🇳 · Guang-You Qin🇨🇳

    We study the medium-induced gluon emission from a hard quark jet traversing the dense nuclear matter within the framework of deep inelastic scattering off a large nucleus. We extend the previous work and compute the single gluon emission spectrum including both transverse and longitudinal momentum exchanges between the hard jet parton and the medium constituents. On the other hand, with only transverse scattering and using static scattering centers for the traversed medium, our induced gluon emission spectrum in the soft gluon limit reduces to the Gyulassy-Levai-Vitev one-rescattering-one-emission formula.

    Comments:
    16 pages, 13 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1804.00470 [pdf]
    PRC(2018)·9 citations
  7. 07

    [Submitted on 2 Apr 2018]

    Event patterns from negative pion spectra in proton-proton and nucleus-nucleus collisions at SPS

    Ya-Hui Chen🇨🇳 · Fu-Hu Liu🇨🇳 · Edward K. Sarkisyan-Grinbaum🇨🇭

    Rapidity-dependent transverse momentum spectra of negatively charged pions measured at different rapidities in proton-proton collisions at the Super Proton Synchrotron (SPS) at various energies within its Beam Energy Scan (BES) program are investigated by using one- and two-component standard distributions where the chemical potential and spin property of particles are implemented. The rapidity spectra are described by a double-Gaussian distribution. At the stage of kinetic freeze-out, the event patterns are structured by the scatter plots in the three-dimensional subspaces of velocity, momentum and rapidity. The results of the studies of the rapidity-independent transverse mass spectra measured at mid-rapidity in proton-proton collisions are compared with those based on the similar transverse mass spectra measured in the most central beryllium-beryllium, argon-scandium and lead-lead collisions from the SPS at its BES energies.

    Comments:
    17 pages, 9 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1804.00571 [pdf]
    CPC(2018)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE