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Nuclear Theory·nucl-th

Monday·May 28, 2018

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 01

    [Submitted on 25 May 2018]

    Tensor correlations in He and Be with antisymmetrized quasi cluster model

    H. Matsuno · Y. Kanada-En'yo · N. Itagaki

    In this paper, we extend the framework of improved version of simplified method to take into account the tensor contribution (SMT) and propose AQCM-T, tensor version of antisymmetrized quasi cluster model (AQCM). Although AQCM-T is phenomenological, we can treat the - coupling in the deuteron-like -pair induced by the tensor interaction in a very simplified way, which allows us to proceed to heavier nuclei. Also we propose a new effective interaction, V2m, where the triplet-even channel of the Volkov No.2 interaction is weakened to 60% so as to reproduce the binding energy of He after including the tensor term of a realistic interaction. Using AQCM-T and the new interaction, the significant tensor contribution in He is shown, which is almost comparable the central interaction, where -state mixes by 8% to the major -state. The AQCM-T model with the new interaction is also applied to Be. It is found that the tensor suppression gives significant contribution to the short-range repulsion between two {\alpha} clusters.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1805.10087 [pdf]
    PRC(2018)·9 citations
  2. 02

    [Submitted on 25 May 2018]

    Quenching of nuclear matrix elements for decay by chiral two-body currents

    Long-Jun Wang🇺🇸 · Jonathan Engel🇺🇸 · Jiang Ming Yao🇺🇸

    We examine the leading effects of two-body weak currents from chiral effective field theory on the matrix elements governing neutrinoless double-beta decay. In the closure approximation these effects are generated by the product of a one-body current with a two-body current, yielding both two- and three-body operators. When the three-body operators are considered without approximation, they quench matrix elements by about 10%, less than suggested by prior work, which neglected portions of the operators. The two-body operators, when treated in the standard way, can produce much larger quenching. In a consistent effective field theory, however, these large effects become divergent and must be renormalized by a contact operator, the coefficient of which we cannot determine at present.

    Comments:
    6 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1805.10276 [pdf]
    PRC(2018)·62 citations
  3. 03

    [Submitted on 25 May 2018] (cross-list from hep-th)

    Universal aspects of the phase diagram of QCD with heavy quarks

    Jan Maelger🇫🇷 · Urko Reinosa🇫🇷 · Julien Serreau🇫🇷

    The flavor dependence of the QCD phase diagram presents universal properties in the heavy quark limit. For the wide class of models where the quarks are treated at the one-loop level, we show, for arbitrary chemical potential, that the flavor dependence of the critical quark masses-for which the confinement-deconfinement transition is second order-is insensitive to the details of the (confining) gluon dynamics and that the critical temperature is constant along the corresponding critical line. We illustrate this with explicit results in various such one-loop models studied in the literature: effective matrix models for the Polyakov loop, the Curci-Ferrari model, and a recently proposed Gribov-Zwanziger-type model. We further observe that the predictions which follow from this one-loop universality property are well satisfied by different calculations beyond one-loop order, including lattice simulations. For degenerate quarks, we propose a simple universal law for the flavor dependence of the critical mass, satisfied by all approaches.

    Comments:
    4 pages, 1 figure ; published version
    Subjects:
    High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1805.10015 [pdf]
    PRD(2018)·35 citations
  4. 04

    [Submitted on 25 May 2018] (cross-list from astro-ph.SR)

    Nuclear processes in Astrophysics: Recent progress

    V. Liccardo · M. Malheiro · M. S. Hussein · B. V. Carlson · T. Frederico

    The origin of the elements is a fascinating question that scientists have been trying to answer for the last seven decades. The formation of light elements in the primordial universe and heavier elements in astrophysical sources occurs through nuclear reactions. We can say that nuclear processes are responsible for the production of energy and synthesis of elements in the various astrophysical sites. Thus, nuclear reactions have a determining role in the existence and evolution of several astrophysical environments, from the Sun to the spectacular explosions of supernovae. Nuclear astrophysics attempts to address the most basic and important questions of our existence and future. There are still many issues that are unresolved such as, how stars and our Galaxy have formed and how they evolve, how and where are the heaviest elements made, what is the abundance of nuclei in the universe and what is the nucleosynthesis output of the various production processes and why the amount of lithium-7 observed is less than predicted. In this paper, we review our current understanding of the different astrophysical nuclear processes leading to the formation of chemical elements and pay particular attention to the formation of heavy elements occurring during high-energy astrophysical events. Thanks to the recent multi-messenger observation of a binary neutron star merger, which also confirmed production of heavy elements, explosive scenarios such as short gamma-ray bursts and the following kilonovae are now strongly supported as nucleosynthesis sites.

    Comments:
    29 pages, 9 figures
    Subjects:
    Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1805.10183 [pdf]
    EPJA(2018)·14 citations
  5. 05

    [Submitted on 25 May 2018] (cross-list from astro-ph.HE)

    The process in the light of an improved understanding of supernova neutrino spectra

    A. Sieverding🇩🇪 · G. Martínez-Pinedo🇩🇪 · L. Huther🇩🇪 · K. Langanke🇩🇪 · A. Heger🇦🇺

    We study the neutrino-induced production of nuclides in explosive supernova nucleosynthesis for progenitor stars with solar metallicity including neutrino nucleus reactions for all nuclei with charge numbers with average neutrino energies in agreement with modern Supernova simulations. Considering progenitors with initial main sequence masses between 13~M and 30~M, we find a significant production of B, La, and Ta by neutrino nucleosynthesis, despite the significantly reduced neutrino energies. The production of F turns out to be more sensitive to the progenitor mass and structure than to the process. With our complete set of cross sections we have identified effects of the ~process on several stable nuclei including S, Ar, K, Co, and In at the 10\% level. Neutrino-induced reactions contribute to a similar extent to the production of radioactive Al and increase the yield of Na by 50\%. Future ~ray astronomy missions may reach the precision at which the contribution from the ~process becomes relevant. We find that the production of Na by the ~process could explain the Ne-E(L) component of meteoritic graphite grains. The ~process enhances the yield of Cl and we point out that the resulting Cl/Cl ratio is in agreement with the values infrerred for the early solar system. Our extended set of neutrino-nucleus interactions also allows us to exclude any further effects of the process on stable nuclei and to quantify the effects on numerous, hitherto unconsidered radioactive nuclei, e.g., Cl, As, Rb, and Y.

    Comments:
    18 pages, 14 figures, 3 tables; submitted to ApJ
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1805.10231 [pdf]
    ApJ(2018)·58 citations

Affiliations

first authorsco-authorsvia INSPIRE