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Nuclear Theory·nucl-th

Tuesday·May 24, 2016

7 papers—2 primary·5 cross-listed

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  1. 01

    [Submitted on 23 May 2016]

    A possible framework of the Lipkin model obeying the su(n)-algebra in arbitrary fermion number. II --- Two subalgebras in the su(n)-Lipkin model and an approach to the construction of linearly independent basis ---

    Yasuhiko Tsue (Kochi Univ., Japan) · Constanca Providencia (Univ. de Coimbra, Portugal) · Joao da Providencia (Univ. de Coimbra, Portugal) · Masatoshi Yamamura (Kansai Univ., Japan)

    Standing on the results for the minimum weight states obtained in the previous paper (I), an idea how to construct the linearly independent basis is proposed for the su(n)-Lipkin model. This idea starts in setting up m independent su(2)-subalgebras in the cases with n=2m and n=2m+1 (m=2,3,4,...). The original representation is re-formed in terms of the spherical tensors for the su(n)-generators built under the su(2)-subalgebras. Through this re-formation, the su(m)-subalgebra can be found. For constructing the linearly independent basis, not only the su(2)-algebras but also the su(m)-subalgebra play a central role. Some concrete results in the cases with n=2, 3, 4 and 5 are presented.

    Comments:
    25 pages, 1 figure
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1605.06880 [pdf]
    PTEP(2016)·2 citations
  2. 02

    [Submitted on 23 May 2016]

    An octahedral deformation with six alpha particles at the Z = 12 system, Mg nuclides: Third nucleons, Alpharons

    Chang-Bum Moon

    We suggest that the emergence of a large deformation in the magnesium, Mg, nuclides, especially at the Z = 12, N = 12, should be associated with an octahedral deformed shape. Within the framework of molecular geometrical symmetry, we find a possibility that the Z = 12, N = 12 system would form an octahedral structure consisting of six points of alpha(4He) particles, yielding the ground collectivity. With this point of view, we draw the following serial molecular structures; the Z = 10, N = 10, 20Ne, corresponds to a hexahedral, the Z = 8, N = 8, 16O, does to a tetrahedral, and the Z = 6, N = 6, 12C, does to a trigonal symmetry. Moreover, the Z = 2, N = 2, 4He(alpha), fits into a tetrahedral symmetry with four points of nucleons; two protons and two neutrons. The enhanced deformation at Z = 12 with N > 20 would be explained by a deformed shape related to an Ethene(Ethylene)-like skeleton with six alpha particles. The deformation at Z = 10, with N = 10 and 12, can be interpreted as being attributed to a hexahedral shape combined by five alpha particles as well. By noticing that the Z = 4, N = 4 system is unstable to the ground state under two-body system with two alpha particles, we conclude that alpha particles, rather than the eight-protons-neutrons nucleon, govern the 8Be stability. Accordingly, the alpha particle should be a third nucleon, like a proton or a neutron, in a nucleus. We name it the 'Alpharon'. With this picture, we are able to open a new gate toward understanding of nuclear many-body systems; nucleon-nucleon interaction, shell structures, nucleon-synthesis, and nuclear matters. We argue that nature favors three-body systems; three quarks for a nucleon, three nucleons for a nucleus.

    Comments:
    Keywords: national nuclear data center (NNDC), molecular structures, octahedral symmetry, tetrahedral symmetry, ethene-like symmetry, Alpharons (alpha). double halos. Nuclides: 3He, 4He, 6He, 8He, 10He, 20Ne, 22Ne, 30Ne, 20Mg, 22Mg, 24Mg, 26Mg, 28Mg, 30Mg, 32Mg, 34Mg, 36Mg, 38Mg, 40Mg
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1605.06913 [pdf]
    0 citations
  3. 03

    [Submitted on 21 May 2016] (cross-list from hep-ph)

    Triangle diagram in heavy-baryon chiral perturbation theory

    Songlin Lyu🇨🇳 · Bingwei Long🇨🇳

    The pion-baryon triangle diagram is inspected for a special kinematic region where the squared momentum transfer is close to : . Instead of arguing on the ground of anomalous threshold, we investigate possible impacts on power counting. The pion can have very small energies, as opposed to in the physical region, which allows all three propagators to be extremely near their mass shell and contributes significantly to the loop integral. We find that in this narrow kinematic window the static-limit approximation for the baryon propagator is invalid and the resummation of the kinetic energy is necessary. Interestingly, in contrast to low-energy two-baryon processes, this resummation of baryon recoils does not lead to overall enhancement of power counting of the diagram.

    Comments:
    Fixed errors in power counting argument, and conclusion partially changed. Baryon recoil term is still found to be crucial, but its resummation does not enhance the diagram
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1605.06712 [pdf]
    J.Phys.G(2019)·2 citations
  4. 04

    [Submitted on 22 May 2016] (cross-list from hep-ph)

    Probing Multi-Strange Dibaryon with Proton-Omega Correlation in High-energy Heavy Ion Collisions

    Kenji Morita🇯🇵 · Akira Ohnishi🇯🇵 · Faisal Etminan🇮🇷 · Tetsuo Hatsuda🇯🇵

    Two-particle intensity correlation between the proton () and the Omega-baryon () in high-energy heavy ion collisions is studied to unravel the possible spin-2 dibaryon recently suggested by lattice QCD simulations. The ratio of correlation functions between small and large collision systems, , is proposed to be a new measure to extract the strong interaction without much contamination from the Coulomb attraction. Relevance of this quantity to the experimental observables in heavy-ion collisions is also discussed.

    Comments:
    6 pages, 5 figures, to appear in Phys. Rev. C (Rapid Communication)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1605.06765 [pdf]
    PRC(2016)·98 citations
  5. 05

    [Submitted on 23 May 2016] (cross-list from hep-ph)

    Lower and upper bounds on the mass of light quark-antiquark scalar resonance in the SVZ sum rules

    S. S. Afonin🇷🇺

    The calculation of the mass of light scalar isosinglet meson within the Shifman-Vainshtein-Zakharov (SVZ) sum rules is revisited. We develop simple analytical methods for estimation of hadron masses in the SVZ approach and try to reveal the origin of their numerical values. The calculations of hadron parameters in the SVZ sum rules are known to be heavily based on a choice of the perturbative threshold. This choice requires some important ad hoc information. We show analytically that the scalar mass under consideration has a lower and upper bound which are independent of this choice: GeV.

    Comments:
    Matches the published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1605.07040 [pdf]
    Int.J.Mod.Phys.A(2016)·6 citations
  6. 06

    [Submitted on 23 May 2016] (cross-list from hep-ph)

    A real-time lattice simulation of the thermalization of a gluon plasma: first results

    Maximilian Attems🇪🇸 · Owe Philipsen🇩🇪 · Christian Schäfer🇩🇪 · Björn Wagenbach🇩🇪 · Savvas Zafeiropoulos🇩🇪

    To achieve an understanding of the thermalization of a quark-gluon plasma, starting from QCD without using model assumptions, is a formidable task. We study the early stage dynamics of a relativistic heavy ion collision in the framework of real time simulations of classical Yang-Mills theory in a static box with the color glass condensate as initial condition. Our study generalizes a previous one by Fukushima and Gelis from SU(2) to the realistic case of SU(3). We calculate the chromo-electric and chromo-magnetic energy densities as well as the ratio of longitudinal and transverse pressure as a function of time as probes for thermalization. Our preliminary results on coarse lattices show the occurrence of Weibel instabilities prior to thermalization.

    Comments:
    6 pages, 2 figures; Proceedings of Excited QCD 2016, March 6-12 2016, Costa da Caparica, Lisbon, Portugal
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1605.07064 [pdf]
    Acta Phys.Polon.Supp.(2016)·3 citations
  7. 07

    [Submitted on 23 May 2016] (cross-list from hep-ph)

    3-D Glasma initial state for relativistic heavy ion collisions

    Bjoern Schenke🇺🇸 · Soeren Schlichting🇺🇸

    We extend the impact parameter dependent Glasma model (IP-Glasma) to three dimensions using explicit small x evolution of the two incoming nuclear gluon distributions. We compute rapidity distributions of produced gluons and the early time energy momentum tensor as a function of space-time rapidity and transverse coordinates. We study rapidity correlations and fluctuations of the initial geometry and multiplicity distributions and compare to existing models for the three dimensional initial state.

    Comments:
    11 pages, 14 figures, version accepted for publication in PRC
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1605.07158 [pdf]
    PRC(2016)·110 citations

Affiliations

first authorsco-authorsvia INSPIRE