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Nuclear Theory·nucl-th

Wednesday·June 14, 2023

9 papers—4 primary·5 cross-listed

All9Primary4Cross-lists5
  1. 05

    [Submitted on 13 Jun 2023] (cross-list from astro-ph.HE)

    Shear and interface modes in neutron stars with pasta structures

    Hajime Sotani

    We carefully examine the shear and interface modes, which are excited due to the presence of crust elasticity, in neutron stars with pasta structures, adopting the relativistic Cowling approximation. We find that the shear modes are independent of the presence of the cylindrical-hole and spherical-hole nuclei at least up to a few kilohertz, while the interface modes strongly depend on the presence of the cylindrical-hole and spherical-hole nuclei. In addition, we find empirical relations for the interface mode frequencies multiplied by the stellar mass and for the shear mode frequencies multiplied by the stellar radius. These relations are expressed as a function of the stellar compactness almost independently of the stiffness in a higher-density region inside the neutron star, once one selects the crust equation of state. Thus, if one would simultaneously observe the shear and interface modes from a neutron star, one might extract the neutron star mass and radius with the help of the constraint on the crust stiffness obtained from terrestrial experiments.

    Comments:
    Accepted for publication in RPD
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2306.07531 [pdf]
    PRD(2023)·11 citations
  2. 06

    [Submitted on 13 Jun 2023] (cross-list from hep-th)

    Causality Criteria from Stability Analysis at Ultra-High Boost

    Shuvayu Roy🇮🇳 · Sukanya Mitra🇮🇳

    In this work, we have exclusively employed the linear stability analysis at ultra-high boost on two well-known stable-causal theories - second-order MIS and first-order BDNK, to identify the region of parameter space over which they are frame-invariantly stable and obey causal signal propagation. It has been shown that at near-luminal boost, stability criteria alone can provide the causality constraints on transport coefficients, which are identical to the asymptotic causality conditions, without actually going to the asymptotic limit of the theories. Thus, we present an alternative approach to derive the causality constraints, which is more appropriate for low-energy effective theories like relativistic hydrodynamics.

    Comments:
    8+1 pages, 2 figures, 1 supplementary material. Version accepted in Phys. Rev. D
    Subjects:
    High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2306.07564 [pdf]
    PRD(2024)·8 citations
  3. 07

    [Submitted on 13 Jun 2023] (cross-list from astro-ph.HE)

    R-process beta-decay neutrino flux from binary neutron star mergers and collapsars

    Yu An🇨🇳 · Meng-Ru Wu🇹🇼 · Gang Guo🇨🇳 · Yue-Lin Sming Tsai🇨🇳 · Shih-Jie Huang🇹🇼 · Yi-Zhong Fan🇨🇳

    This study investigates the antineutrinos production by -decay of -process nuclei in two astrophysical sites that are capable of producing gamma-ray bursts (GRBs): binary neutron star mergers (BNSMs) and collapsars, which are promising sites for heavy element nucleosynthesis. We employ a simplified method to compute the -decay energy spectrum and consider a number of different representative thermodynamic trajectories for -process simulations, each with four sets of distribution. The time evolution of the spectrum is derived for both the dynamical ejecta and the disk wind for BNSMs and collapsar outflow, based on approximated mass outflow rates. Our results show that the has an average energy of approximately 3 to 9~MeV, with a high energy tail of up to 20 MeV. The flux evolution is primarily determined by the outflow duration, and can thus remain large for ~s and ~s for BNSMs and collapsars, respectively. For a single merger or collapsar at 40~Mpc, the flux is ~cm~s, indicating a possible detection horizon up to ~Mpc for Hyper-Kamiokande. We also estimate their contributions to the diffuse background, and find that both sources should only contribute subdominantly to the diffuse background when compared to that expected from core-collapse supernovae.

    Comments:
    14 pages, 8 figures
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2306.07659 [pdf]
    PRD(2023)·8 citations
  4. 08

    [Submitted on 13 Jun 2023] (cross-list from nucl-ex)

    Rotation of pear-shaped Ru nucleus

    A. Karmakar · P. Datta · Soumik Bhattacharya · Shabir Dar · S. Bhattacharyya · G. Mukherjee · H. Pai · S. Basu · S. Nandi · S. S. Nayak · Sneha Das · R. Raut and 5 other authors

    Atomic nuclei in general can have deformed shapes and nearly all these shapes are symmetric with respect to reflection. Only a few Actinide nuclei have stable reflection asymmetric pear shapes in their ground state and exhibit characteristic rotational bands. In this article, we report on the observation of two alternate parity rotational bands in 100Ru, which are connected by seven interleaved electric dipole transitions and their rates are found to be enhanced. In addition, the moments of inertia associated with these two opposite parity rotational bands have been found to be similar. These experimental observations indicate the rotation of a stable pear-shaped 100Ru nucleus, which is the first such observation outside the Actinide mass region. This shape is built on an excited configuration and originates from the rotational alignment of the angular momenta of a pair of neutrons. This unique observation establishes an alternate mechanism by which an atomic nucleus can assume a pear shape.

    Comments:
    13 pages, 7 figures, 2 tables
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2306.07670 [pdf]
    1 citation
  5. 09

    [Submitted on 13 Jun 2023] (cross-list from hep-ph)

    Heavy quark radiation in an anisotropic hot QCD medium

    Jai Prakash🇮🇳 · Vinod Chandra🇮🇳 · Santosh K. Das🇮🇳

    The impact of momentum anisotropy on the heavy quarks (HQs) dynamics has been investigated in a hot QCD medium while considering both collisional and radiative processes within the ambit of the Fokker-Planck approach. The relative orientation of the HQs motion (momentum vector) with respect to the direction of anisotropy is responsible for the character of transport coefficients. Therefore, the drag and diffusion coefficients of the HQs are decomposed, respectively, into two and four components by considering a general tensor basis. Each component of the drag and diffusion coefficient of the HQs has been analyzed in detail. It is observed that the anisotropy has a significant impact on the transport coefficients of the HQ for both the collisional and the radiational processes. The nuclear suppression factor, , has been computed considering the anisotropic medium. It is observed that the momentum anisotropy affects the of the HQs significantly in both elastic and inelastic cases.

    Comments:
    Published in Physical Review D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2306.07966 [pdf]
    PRD(2023)·24 citations

Affiliations

first authorsco-authorsvia INSPIRE