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Nuclear Theory·nucl-th

Thursday·June 8, 2017

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 01

    [Submitted on 7 Jun 2017]

    Quark matter revisited with non extensive MIT bag model

    Pedro H. G. Cardoso🇧🇷 · Tiago Nunes da Silva🇧🇷 · Airton Deppman🇧🇷 · Débora P. Menezes🇧🇷

    In this work we revisit the MIT bag model to describe quark matter within both the usual Fermi-Dirac and the Tsallis statistics. We verify the effects of the non-additivity of the latter by analysing two different pictures: the first order phase transition of the QCD phase diagram and stellar matter properties. While, the QCD phase diagram is visually affected by the Tsallis statistics, the resulting effects on quark star macroscopic properties are barely noticed.

    Comments:
    10 pagens, 5 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1706.02183 [pdf]
    EPJA(2017)·46 citations
  2. 02

    [Submitted on 7 Jun 2017]

    Proxy-SU(3) symmetry in heavy deformed nuclei

    Dennis Bonatsos · I. E. Assimakis · N. Minkov · Andriana Martinou · R. B. Cakirli · R. F. Casten · K. Blaum

    Background: Microscopic calculations of heavy nuclei face considerable difficulties due to the sizes of the matrices that need to be solved. Various approximation schemes have been invoked, for example by truncating the spaces, imposing seniority limits, or appealing to various symmetry schemes such as pseudo-SU(3). This paper proposes a new symmetry scheme also based on SU(3). This proxy-SU(3) can be applied to well-deformed nuclei, is simple to use, and can yield analytic predictions. Purpose: To present the new scheme and its microscopic motivation, and to test it using a Nilsson model calculation with the original shell model orbits and with the new proxy set. Method: We invoke an approximate, analytic, treatment of the Nilsson model, that allows the above vetting and yet is also transparent in understanding the approximations involved in the new proxy-SU(3). Results: It is found that the new scheme yields a Nilsson diagram for well-deformed nuclei that is very close to the original Nilsson diagram. The specific levels of approximation in the new scheme are also shown, for each major shell. Conclusions: The new proxy-SU(3) scheme is a good approximation to the full set of orbits in a major shell. Being able to replace a complex shell model calculation with a symmetry-based description now opens up the possibility to predict many properties of nuclei analytically and often in a parameter-free way. The new scheme works best for heavier nuclei, precisely where full microscopic calculations are most challenged. Some cases in which the new scheme can be used, often analytically, to make specific predictions, are shown in a subsequent paper.

    Comments:
    24 pages, 6 figures, 15 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1706.02282 [pdf]
    PRC(2017)·98 citations

Affiliations

first authorsco-authorsvia INSPIRE