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Nuclear Theory·nucl-th

Monday·November 9, 2020

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 01

    [Submitted on 6 Nov 2020]

    Variational approach with the superposition of the symmetry-restored quasi-particle vacua for nuclear shell-model calculations

    Noritaka Shimizu · Yusuke Tsunoda · Yutaka Utsuno · Takaharu Otsuka

    We propose a variational calculation scheme utilizing the superposition of the angular-momentum, parity, number projected quasiparticle vacua, that is especially suitable for applying to medium-heavy nuclei in shell-model calculations. We derive a formula for the energy variance with quasi-particle vacua and apply the energy-variance extrapolation to the present scheme for further precise estimation of the exact shell-model energy. The validity of the method is presented for the shell-model calculation of Ba in the model space. We also discuss the feasibility of this scheme in the case of the Nd in the and model space and demonstrate that its neutrinoless-double-beta-decay matrix element is obtained showing good convergence.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2011.03157 [pdf]
    PRC(2021)·42 citations
  2. 02

    [Submitted on 6 Nov 2020]

    Properties of Isoscalar Giant Multipole Resonances in medium-heavy closed-shell nuclei: a semimicroscopic description

    M. L. Gorelik (1) · S. Shlomo (2, 3) · B. A. Tulupov (4) · M. H. Urin (5) ((1) Moscow Economic School, Moscow, Russia, (2) Cyclotron Institute, Texas A&M University, College Station, USA, (3) Department of Elementary Particles and Astrophysics, the Weizmann Institute of Science, Rehovot, Israel, (4) Institute for Nuclear Research, RAS, Moscow, Russia, (5) National Research Nuclear University ''MEPhI'', Moscow, Russia)

    The semimicroscopic particle-hole dispersive optical model (PHDOM) is implemented to describe main properties of Isoscalar Giant Multipole Resonances (up to L=3) in medium-heavy closed-shell nuclei. The main properties are characterized by the strength distribution, transition density, partial and total probabilities of direct one-nucleon decay. Calculation results obtained for the 208Pb nucleus are compared with available experimental data.

    Comments:
    33 pages, 6 tables, 8 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2011.03315 [pdf]
    PRC(2021)·9 citations
  3. 03

    [Submitted on 6 Nov 2020]

    Shear viscosity and electric conductivity of a hot and dense QGP with a chiral phase transition

    Olga Soloveva🇩🇪 · David Fuseau🇫🇷 · Jörg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪

    We calculate two transport coefficients -- the shear viscosity over entropy ratio and the ratio of the electric conductivity to the temperature -- of strongly interacting quark matter within the extended Polyakov Nambu-Jona-Lasinio (PNJL) model along the crossover transition line for moderate values of baryon chemical potential GeV as well as in the vicinity of the critical endpoint (CEP) and at large baryon chemical potential GeV, where the first-order phase transition takes place. The evaluation of the transport coefficients is performed on the basis of the effective Boltzmann equation in the relaxation time approximation. We employ two different methods for the calculation of the quark relaxation times: i) using the averaged transition rate defined via thermal averaged quark-quark and quark-antiquark PNJL cross sections and ii) using the 'weighted' thermal averaged quark-quark and quark-antiquark PNJL cross sections. The and transport coefficients have a similar temperature and chemical potential behavior when approaching the chiral phase transition for the both methods for the quark relaxation time, however, the differences grow with increasing temperature. We demonstrate the effect of the first-order phase transition and of the CEP on the transport coefficients in the deconfined QCD medium.

    Comments:
    16 pages, 21 figures, 4 tables
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2011.03505 [pdf]
    PRC(2021)·42 citations
  4. 04

    [Submitted on 6 Nov 2020] (cross-list from astro-ph.HE)

    Estimating the nuclear saturation parameter via low-mass neutron star asteroseismology

    Hajime Sotani

    We examine the fundamental (-) and the 1st pressure (-) mode frequencies in gravitational waves from cold neutron stars constructed with various unified realistic equations of state. With the calculated frequencies, we derive the empirical formulae for the - and -mode frequencies, and , as a function of the square root of the stellar average density and the parameter (), which is a combination of the nuclear saturation parameters. With our empirical formulae, we show that by simultaneously observing the - and -mode gravitational waves, when (which corresponds to neutron star models with the mass of ), one could estimate the value of within accuracy, which makes a strong constraint on the EOS for neutron star matter. In addition, we find that the maximum -mode frequency is strongly associated with the minimum radius of neutron star. That is, if one would observe a larger frequency of the -mode, one might constrain the upper limit of the minimum neutron star radius.

    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2011.03167 [pdf]
    PRD(2020)·21 citations
  5. 05

    [Submitted on 6 Nov 2020] (cross-list from hep-ph)

    Covariant formulation of gluon self-energy in presence of ellipsoidal anisotropy

    Ritesh Ghosh🇮🇳 · Bithika Karmakar🇮🇳 · Arghya Mukherjee🇮🇳

    In this work, a covariant formulation of the gluon self-energy in presence of ellipsoidal anisotropy is considered. It is shown that the general structure of the gluon self-energy can be written in terms of six linearly independent projection tensors. Similar to the spheroidal anisotropy, mass scales can be introduced for each of the collective modes considering the static limits. With a simplified ellipsoidal generalization of the Romatschke-Strickland form, the angular dependencies of the mass scales are studied. It is observed that, compared to the spheroidal case, additional unstable mode may appear in presence of ellipsoidal anisotropy depending upon the choice of the parameters.

    Comments:
    10 pages, 3 figures, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2011.03374 [pdf]
    PRD(2020)·10 citations
  6. 06

    [Submitted on 6 Nov 2020] (cross-list from hep-ph)

    Partial decay widths of to kaonic resonances

    Brenda B. Malabarba🇧🇷 · Xiu-Lei Ren🇩🇪 · K. P. Khemchandani🇧🇷 · A. Martinez Torres🇧🇷

    In this work we study the strong decays of to final states involving the kaonic resonances , and , on which experimental data have recently been extracted by the BESIII Collaboration. The formalism developed here is based on interpreting and as states arising from three-hadron dynamics, which is inspired by our earlier works. For and we investigate different descriptions, such as a mixture of states belonging to the nonet of axial resonances, or the former one as a state originating from the vector-pseudoscalar dynamics. The ratios among the partial widths of , and obtained are compatible with the experimental results, reinforcing the three-body nature of . Within our formalism, we can also explain the suppressed decay of to , as found by the BESIII Collaboration. Furthermore, our results can be useful in clarifying the properties of , and when higher statistics data would be available.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2011.03448 [pdf]
    PRD(2021)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE