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Nuclear Theory·nucl-th

Friday·December 25, 2020

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 01

    [Submitted on 24 Dec 2020]

    Tensor-force effects on shell-structure evolution in isotones and isotopes in the relativistic Hartree-Fock theory

    Zhiheng Wang · Tomoya Naito · Haozhao Liang

    The evolution of the energy difference between the neutron states and in the isotones and that between the proton states and in the isotopes are investigated within the framework of the relativistic Hartree-Fock theory, using the density-dependent effective interactions PKA1 and PKO (, , ). By identifying the contributions of the tensor force, which is naturally induced via the Fock terms, we find that the tensor force plays crucial roles in the evolution of the shell structure. The strength of the tensor force is also explored. It is found that moderately increasing the coupling strength of pion-nucleon coupling, i.e., , will significantly improve the description of the shell-structure evolution. In particular, reducing the density dependence of is shown to be more preferable, in comparison to enlarging with a factor. This is in consistence with the idea of "tensor renormalization persistency" and provides valuable guidance for the development of nuclear energy density functional in the relativistic framework.

    Comments:
    15 pages, 7 figures, 3 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2012.13143 [pdf]
    PRC(2021)·9 citations
  2. 02

    [Submitted on 24 Dec 2020]

    Kinetic Energy Distribution of Fragments for Thermal Neutron-Induced U and Pu Fission Reactions

    Xiaojun Sun · Haiyuan Peng · Liying Xie · Kai Zhang · Yan Liang · Yinlu Han · Nengchuan Su · Jie Yan · Jun Xiao · Junjie Sun

    Focused on the generation and evolution of vast complementary pairs of the primary fission fragments at scission moment, Dinuclear and Statistical Model (DSM) is proposed. (1) It is assumed that the fissile nucleus elongates along a symmetric coaxis until it breaks into two primary fission fragments. (2) Every complementary pair of the primary fission fragments is approximatively described as two ellipsoids with large deformation at scission moment. (3) The kinetic energy in every complementary pair of the primary fragments is mainly provided by Coulomb repulsion, which is explicitly expressed through strict six-dimensional integrals. (4) Only three phenomenological coefficients are obtained to globally describe the quadrupole deformation parameters of arbitrary primary fragments both for U() and Pu() reactions, on the basis of the common characteristics of the measured data, such as mass and charge distributions, kinetic energy distributions. In the framework of DSM, the explicit average total kinetic energy distribution and the average kinetic energy distribution are consistently represented. The theoretical results in this paper agree well with the experimental data. Furthermore, this model is expected as the reliable approach to generally evaluate the corresponding observebles for thermal neutron-induced fission of actinides.

    Comments:
    13pages, 12 figures, 6 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2012.13281 [pdf]
    1 citation
  3. 03

    [Submitted on 24 Dec 2020]

    19B isotope as a 17B-n-n three-body cluster close to unitary limit

    J. Carbonell🇫🇷 · E. Hiyama🇯🇵 · R. Lazauskas🇫🇷 · F. M. Marqués🇫🇷

    We describe 19B in terms of a 17B-n-n three-body system, where the two-body subsystems 17B-n and n-n are unbound (virtual) states close to the unitary limit. The energy of 19B ground state is well reproduced and two low-lying resonances are predicted. Their eventual link with the Efimov physics is discussed. This model can be extended to describe the recently discovered resonant states in 20,21B.

    Comments:
    27th International Nuclear Physics Conference (INPC2019). arXiv admin note: substantial text overlap with arXiv:1912.05427
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2012.13342 [pdf]
    J.Phys.Conf.Ser.(2020)·0 citations
  4. 04

    [Submitted on 24 Dec 2020] (cross-list from astro-ph.IM)

    Detection and Parameter Estimation of Gravitational Waves from Binary Neutron-Star Mergers in Real LIGO Data using Deep Learning

    Plamen G. Krastev · Kiranjyot Gill · V. Ashley Villar · Edo Berger

    One of the key challenges of real-time detection and parameter estimation of gravitational waves from compact binary mergers is the computational cost of conventional matched-filtering and Bayesian inference approaches. In particular, the application of these methods to the full signal parameter space available to the gravitational-wave detectors, and/or real-time parameter estimation is computationally prohibitive. On the other hand, rapid detection and inference are critical for prompt follow-up of the electromagnetic and astro-particle counterparts accompanying important transients, such as binary neutron-star and black-hole neutron-star mergers. Training deep neural networks to identify specific signals and learn a computationally efficient representation of the mapping between gravitational-wave signals and their parameters allows both detection and inference to be done quickly and reliably, with high sensitivity and accuracy. In this work we apply a deep-learning approach to rapidly identify and characterize transient gravitational-wave signals from binary neutron-star mergers in real LIGO data. We show for the first time that artificial neural networks can promptly detect and characterize binary neutron star gravitational-wave signals in real LIGO data, and distinguish them from noise and signals from coalescing black-hole binaries. We illustrate this key result by demonstrating that our deep-learning framework classifies correctly all gravitational-wave events from the Gravitational-Wave Transient Catalog, GWTC-1 [Phys. Rev. X 9 (2019), 031040]. These results emphasize the importance of using realistic gravitational-wave detector data in machine learning approaches, and represent a step towards achieving real-time detection and inference of gravitational waves.

    Comments:
    10 pages, 8 figures, 1 table. Updated grant information. Published in Physics Letters B
    Subjects:
    Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2012.13101 [pdf]
    PLB(2021)·65 citations
  5. 05

    [Submitted on 24 Dec 2020] (cross-list from hep-ph)

    Relativistic Coulomb S-factor of Two Spinor Particles with Arbitrary Masses

    Yu.D. Chernichenko🇧🇾 · L.P. Kaptari🇷🇺 · O. P. Solovtsova🇧🇾

    A new resummation of the -factor of a composite system of two relativistic spin-1/2 particles of arbitrary masses interacting via a Coulomb-like chromodynamical potential is presented. The analysis is performed in the framework of a relativistic quasipotential approach based on the Hamiltonian formulation of the covariant quantum field theory in the relativistic configuration representation. The pseudoscalar, vector, and pseudovector systems are considered and the behaviour of the -factor near the threshold and in the relativistic limit is investigated in detail. The spin dependence of the -factors is discussed as well. It is argued that at the threshold the contribution of spins significantly reduces the Sommerfeld effect, while at ultrarelativistic velocities their role diminishes and the -factor becomes basically the same as for the spinless systems. A connection between the new and previously obtained S-factors for spinless particles of arbitrary masses and for relativistic spinor particles of equal masses is established.

    Comments:
    23 pages, 5 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2012.13128 [pdf]
    Eur.Phys.J.Plus(2021)·3 citations
  6. 06

    [Submitted on 24 Dec 2020] (cross-list from hep-lat)

    On-shell representations of two-body transition amplitudes: single external current

    Raúl A. Briceño🇺🇸 · Andrew W. Jackura🇺🇸 · Felipe G. Ortega-Gama🇺🇸 · Keegan H. Sherman🇺🇸

    This work explores scattering amplitudes that couple two-particle systems via a single external current insertion, . Such amplitudes can provide structural information about the excited QCD spectrum. We derive an exact analytic representation for these reactions. From these amplitudes, we show how to rigorously define resonance and bound-state form-factors. Furthermore, we explore the consequences of the narrow-width limit of the amplitudes as well as the role of the Ward-Takahashi identity for conserved vector currents. These results hold for any number of two-body channels with no intrinsic spin, and a current with arbitrary Lorentz structure and quantum numbers. This work and the existing finite-volume formalism provide a complete framework for determining this class of amplitudes from lattice QCD.

    Comments:
    35 pages, 13 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2012.13338 [pdf]
    PRD(2021)·32 citations

Affiliations

first authorsco-authorsvia INSPIRE