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Nuclear Theory·nucl-th

Monday·September 16, 2019

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 06

    [Submitted on 13 Sept 2019] (cross-list from nucl-ex)

    Status on fusion at deep subbarrier energies: impact of resonances on astrophysical factors

    C. Beck🇫🇷 · A. M. Mukhamedzhanov🇺🇸 · X. Tang🇨🇳

    Since the discovery of molecular resonances in C+C in the early sixties a great deal of research work has been undertaken to study -clustering and resonant effects of the fusion process at sub-Coulomb barrier energies. The modified astrophysical factors of C+C fusion have been extracted from direct fusion measurements at deep sub-barrier energies near the Gamow window. They were also obtained by the indirect Trojan horse method (THM). A comparison of direct measurements and the THM, which elucidates problems in the analysis of the THM, is discussed in this Letter to the Editor.

    Comments:
    5 pages, 3 figures
    Subjects:
    Nuclear Experiment (nucl-ex); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
    arXiv:
    1909.06021 [pdf]
    EPJA(2020)·38 citations
  2. 07

    [Submitted on 12 Sept 2019] (cross-list from hep-ph)

    Transport coefficients of hot and dense hadron gas in a magnetic field: a relaxation time approach

    Arpan Das🇮🇳 · Hiranmaya Mishra🇮🇳 · Ranjita K. Mohapatra🇮🇳

    We estimate various transport coefficients of hot and dense hadronic matter in the presence of magnetic field. The estimation is done through solutions of the relativistic Boltzmann transport equation in the relaxation time approximation.We have investigated the temperature and the baryon chemical potential dependence of these transport coefficients. Explicit calculations are done for the hadronic matter in the ambit of hadron resonance gas model. We estimate thermal conductivity, electrical conductivity and the shear viscosity of hadronic matter in the presence of a uniform magnetic field. Magnetic field, in general, makes the transport coefficients anisotropic. It is also observed that all the transport coefficients perpendicular to the magnetic field are smaller compared to their isotropic counterpart.

    Comments:
    22 pages, 11 figures. arXiv admin note: text overlap with arXiv:1903.03938
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1909.06202 [pdf]
    PRD(2019)·58 citations
  3. 08

    [Submitted on 13 Sept 2019] (cross-list from hep-ph)

    Fierz-complete NJL model study III: Emergence from quark-gluon dynamics

    Jens Braun🇩🇪 · Marc Leonhardt🇩🇪 · Martin Pospiech🇩🇪

    Our understanding of the dynamics and the phase structure of dense strong-interaction matter is to a large extent still built on the analysis of low-energy models, such as those of the Nambu-Jona-Lasinio-type. In this work, we analyze the emergence of the latter class of models at intermediate and low energy scales from fundamental quark-gluon interactions. To this end, we study the renormalization group flow of a Fierz-complete set of four-quark interactions and monitor their strength at finite temperature and quark chemical potential. At small quark chemical potential, we find that the scalar-pseudoscalar interaction channel is dynamically rendered most dominant by the gauge degrees of freedom, indicating the formation of a chiral condensate. Moreover, the inclusion of quark-gluon interactions leaves a significant imprint on the dynamics as measured by the curvature of the finite-temperature phase boundary which we find to be in accordance with lattice QCD results. At large quark chemical potential, we then observe that the dominance pattern of the four-quark couplings is changed by the underlying quark-gluon dynamics, without any fine-tuning of the four-quark couplings. In this regime, the scalar-pseudoscalar interaction channel becomes subleading and the dominance pattern suggests the formation of a chirally symmetric diquark condensate. In particular, our study confirms the importance of explicit breaking for the formation of this type of condensate at high densities.

    Comments:
    16 pages, 7 figures, 1 table
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1909.06298 [pdf]
    PRD(2020)·88 citations
  4. 09

    [Submitted on 13 Sept 2019] (cross-list from physics.chem-ph)

    Efficient evaluation of AGP reduced density matrices

    Armin Khamoshi · Thomas Henderson · Gustavo Scuseria

    We propose and implement an algorithm to calculate the norm and reduced density matrices of the antisymmetrized geminal power (AGP) of any rank with polynomial cost. Our method scales quadratically per element of the reduced density matrices. Numerical tests indicate that our method is very fast and capable of treating systems with a few thousand orbitals and hundreds of electrons reliably in double-precision. In addition, we present reconstruction formulae that allows one to decompose higher order reduced density matrices in terms of linear combinations of lower order ones, thereby reducing the computational cost significantly.

    Subjects:
    physics.chem-ph (physics.chem-ph); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
    arXiv:
    1909.06345 [pdf]
    J.Chem.Phys.(2019)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE