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Nuclear Theory·nucl-th

Monday·December 20, 2021

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 01

    [Submitted on 16 Dec 2021]

    Locating the special point of hybrid neutron stars

    Mateusz Cierniak🇵🇱 · David Blaschke🇵🇱

    The special point is a feature unique to models of hybrid neutron stars. It represents a location on their mass--radius sequences that is insensitive to the phase transition density. We consider hybrid neutron stars with a core of deconfined quark matter that obeys a constant--sound--speed (CSS) equation of state model and provide a fit formula for the coordinates of the special point as functions of the squared sound speed () and pressure scale () parameters. Using the special point mass as a proxy for the maximum mass of the hybrid stars we derive limits for the CSS model parameters based on the recent NICER constraint on mass and radius of pulsar PSR J0740+6620, and . The upper limit for the maximum mass of hybrid stars depends on the upper limit for so that choosing results in , within the mass range of GW190814.

    Comments:
    8 pages, 5 figures, 1 table
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2112.09166 [pdf]
    EPJ Web Conf.(2022)·8 citations
  2. 02

    [Submitted on 16 Dec 2021]

    Confining density functional approach for color superconducting quark matter and mesonic correlations

    Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱 · Konstantin Maslov🇷🇺

    We present a novel relativistic density-functional approach to modeling quark matter with a mechanism to mimic confinement. The quasiparticle treatment of quarks provides their suppression due to large quark selfenergy already at the mean-field level. We demonstrate that our approach is equivalent to a chiral quark model with medium-dependent couplings. The dynamical restoration of the chiral symmetry is ensured by construction of the density functional. Beyond the mean field, quark correlations in the pseudoscalar channel are described within the Gaussian approximation. This explicitly introduces pionic states into the model. Their contribution to the thermodynamics potential is analyzed within the Beth-Uhlenbeck framework. The modification of the meson mass spectrum in the vicinity of thee (de)confinement transition is interpreted as the Mott transition. Supplemented with the vector repulsion and diquark pairing the model is applied to construct a hybrid quark-hadron EoS of cold compact-star matter. We study the connection of such a hybrid EoS with the stellar mass-radius relation and tidal deformability. The model results are compared to various observational constraints including the NICER radius measurement of PSR J0740+6620 and the tidal deformability constraint from GW170817. The model is shown to be consistent with the constraints, still allowing for further improvement by adjusting the vector repulsion and diquark pairing couplings.

    Comments:
    8 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2112.09223 [pdf]
    EPJ Web Conf.(2022)·6 citations
  3. 03

    [Submitted on 16 Dec 2021]

    Generator coordinate method for transition-state dynamics in nuclear fission

    G.F. Bertsch · K. Hagino

    Since its beginnings, fission theory has asumed that low-energy induced fission takes place through transition-state channels at the barrier tops. Neverthess, up to now there is no microscopic theory applicable to those conditions. We suggest that modern reaction theory is suitable for this purpose, and propose a methodology based on a configuration-interaction framework using the Generator Coordinate Method (GCM). Simple reaction-theoretic models are constructed with the Gaussian Overlap Approximation (GOA) to parameterize both the dynamics within the channels and their incoherent couplings to states outside the barrier. The physical characteristics of the channels examined here are their effective bandwidths and the quality of the coupling to compound-nucleus states as measured by the transmission factor . We also investigate the spacing of GCM states with respect to their degree of overlap. We find that a rather coarse mesh provides an acceptable accuracy for estimating the bandwidths and transmission factors. The common numerical stability problem in using the GCM is avoided due to the choice of meshes and the finite bandwidths of the channels. The bandwidths of the channels are largely controlled by the zero-point energy with respect to the collective coordinate in the GCM configurations.

    Comments:
    This version is the revised version submitted to Physical Review C on 2//22/2022
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2112.09255 [pdf]
    PRC(2022)·11 citations
  4. 04

    [Submitted on 17 Dec 2021]

    Zr Isotopes as a region of intertwined quantum phase transitions

    N. Gavrielov · A. Leviatan · F. Iachello

    The zirconium isotopes with 92110 have one of the most complicated evolution of structure in the nuclear chart. In order to understand the structural evolution of these isotopes, we carry a detailed calculation in a definite symmetry-based framework, the interacting boson model with configuration mixing (IBM-CM). We compare our calculation to a large range of experimental data, such as energy levels, two neutron separation energies, and transition rates, isotope shifts and magnetic moments. The structural evolution of the low lying spectra of these isotopes is explained using the notion of intertwined quantum phase transitions (IQPTs), for which a QPT involving a crossing of two configurations (Type II) is accompanied by a QPT involving a shape evolution of each configuration separately (Type I). In our study, we find the occurrence of Type I QPT within the intruder configuration, changing from weakly deformed to prolate deformed and finally to -unstable, associated with the U(5), SU(3) and SO(6) dynamical symmetry limits of the IBM, respectively. Alongside the Type I QPT, we also find the occurrence of Type II QPT between the normal and intruder configurations, where both Types I and II have a critical-point near . The good agreement of our calculation with the vast empirical data along the chain of isotopes demonstrates the relevance of IQPTs to the zirconium isotopes, and can serve as a case study to set path for new investigations of IQPTs in other nuclei and other physical systems.

    Comments:
    25 pages, 20 figures, 6 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2112.09454 [pdf]
    PRC(2022)·41 citations
  5. 05

    [Submitted on 17 Dec 2021]

    Nuclear transparency of the charged hadron produced in the inclusive electronuclear reaction

    Swapan Das🇮🇳

    The nuclear transparency of the charged hadron produced in the inclusive reaction on the nucleus has been calculated using Glauber model for the nuclear reaction. The color transparency (CT) of the produced hadron and the short-range correlation (SRC) of the nucleons in the nucleus have been incorporated in the Glauber model to investigate their effects on the nuclear transparency of the hadron. The calculated nuclear transparencies for the proton and pion are compared with the data.

    Comments:
    11 papges, 2 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2112.09469 [pdf]
    PRC(2022)·6 citations
  6. 06

    [Submitted on 17 Dec 2021]

    Nuclear level densities away from line of -stability

    T. Ghosh · B. Maheshwari · Sangeeta · G. Saxena · B. K. Agrawal

    The variation of total nuclear level densities (NLDs) and level density parameters with proton number are studied around the -stable isotope, , for a given mass number. We perform our analysis for a mass range to 180 using the NLDs from popularly used databases obtained with the single-particle energies from two different microsopic mass-models. These NLDs which include microscopic structural effects such as collective enhancement, pairing and shell corrections, do not exhibit inverted parabolic trend with a strong peak at as predicted earlier. We also compute the NLDs using the single-particle energies from macroscopic-microscopic mass-model. Once the collective and pairing effects are ignored, the inverted parabolic trends of NLDs and the corresponding level density parameters become somewhat visible. Nevertheless, the factor that governs the dependence of the level density parameter, leading to the inverted parabolic trend, is found to be smaller by an order of magnitude. We further find that the dependence of NLDs is quite sensitive to the shell effects.

    Comments:
    Accepted in Journal of Physics G: Nuclear and Particle Physics
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2112.09563 [pdf]
    J.Phys.G(2022)·2 citations
  7. 07

    [Submitted on 16 Dec 2021]

    Gamows alpha decay theory revisited

    K. D. Krori · Samrat Dey

    G. Gamow's alpha-decay theory (1928), although successful, has a wrong phenomenological argument that an alpha-particle inside a radioactive nucleus moves back and forth through the dense mass of nucleons (retaining its identity) a number of times before it comes out. This short paper seeks to get over this shortcoming by deriving principally the Gamow's theory through a slightly alternative approach by avoiding the problematic touching frequency in the original theory.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2112.09578 [pdf]
    Reson.(2024)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE