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Nuclear Theory·nucl-th

Monday·September 5, 2022

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 01

    [Submitted on 2 Sept 2022]

    Holographic cold dense matter constrained by neutron stars

    Lin Zhang🇨🇳 · Mei Huang🇨🇳

    The equation of state (EoS) for cold dense matter inside neutron stars is investigated by using holographic QCD models in the framework of the Einstein-Maxwell-dilaton (EMD) system and the improved Karch-Katz-Son-Stephanov (KKSS) action for matter part. This method of describing holographic nuclear matter in the EMDKKSS framework is different from that by using the Dirac-Born-Infeld (DBI) action and the Chern-Simons (CS) terms. Combining with the Hebeler-Lattimer-Pethick-Schwenk (HLPS) intermediate equation of state (EoS), the hybrid EoS inside the neutron stars is constructed. The obtained hybrid EoS is located in the range that is defined by the low-density chiral effective theory, the high-density perturbative QCD, and the polytropic interpolations between them, and is constrained by the astrophysics observations. The square of the sound velocity reaches a maximum value larger than in the region of times the saturation baryon number density and approaches the conformal limit at the high baryon density range. The mass-radius relation and the tidal deformability of the neutron stars are in agreement with astrophysical measurements. The possible maximum mass for the neutron star is about and the radius is about then. It is noticed that the holographic quark matter branch in the mass-radius relation is always unstable and the holographic nuclear matter can produce a stable branch. These results indicate that even in the core of the NS, the matter is still in the confinement phase and the quark matter is not favored.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2209.00766 [pdf]
    PRD(2022)·22 citations
  2. 02

    [Submitted on 2 Sept 2022]

    Fermi motion effects in electroproduction of hypernuclei

    P. Bydžovský🇨🇿 · D. Denisova🇨🇿 · D. Skoupil🇨🇿 · P. Veselý🇨🇿

    In a previous analysis of electroproduction of hypernuclei the cross sections were calculated in distorted-wave impulse approximation where the momentum of the initial proton in the nucleus was set to zero (the frozen-proton approximation). In this paper we go beyond this approximation assuming a non zero effective proton momentum due to proton Fermi motion inside of the target nucleus discussing also other kinematical effects. To this end we have derived a more general form of the two-component elementary electroproduction amplitude (Chew-Goldberger-Low-Nambu like) which allows its use in a general reference frame moving with respect to the nucleus-rest frame. The effects of Fermi motion were found to depend on kinematics and elementary amplitudes. The largest effects were observed in the contributions from the longitudinal and interference parts of the cross sections. The extension of the calculations beyond the frozen-proton approximation improved the agreement of predicted theoretical cross sections with experimental data and once we assumed the optimum on-shell approximation, we were able to remove an inconsistency which was previously present in the calculations.

    Comments:
    20 pages, 7 figures, 5 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2209.00881 [pdf]
    PRC(2022)·8 citations
  3. 03

    [Submitted on 2 Sept 2022]

    Phase Shift Analysis of Light Nucleon-Nucleus Elastic Scattering using Reference Potential Approach

    Lalit Kumar · Shikha Awasthi · Anil Khachi · O.S.K.S Sastri

    The neutron and proton scattering with either deuteron or stable alpha particle can be modeled as a two particle system. In this paper, using Morse function as reference potential, inverse potentials have been computationally constructed directly from scattering phase shifts (SPS) data for light nucleon-nucleus systems. The phase equation for various l-channels has been numerically solved using 5th order Runge-Kutta (RK-5) method in each iteration within the optimization procedure to obtain best model parameters of Morse function that minimize mean absolute percentage error (MAPE). The inverse potentials for S-wave of neutron-deuteron and proton-deuteron systems have been obtained with MAPE of 1.95 and 2.05% respectively. Those corresponding to various P and D channels of neutron-alpha(n-alpha) and proton-alpha(p-alpha) systems, have been determined to less than 1.53 and 2.17% respectively. The obtained(experimental) resonance energies for p1/2 and p3/2, from their partial cross-sections plots, respectively are 4.1(4) and 0.93(0.89) for n-alpha and 5.21(5) and 1.96(1.96) for p-alpha system. While total cross-section for n-alpha has been found to be matching with values available in literature, that of p-alpha is seen to be following the correct trend.

    Comments:
    8 pages, 8 figures, 2 Tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2209.00951 [pdf]
    International Journal of Modern Physics E…·9 citations

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first authorsco-authorsvia INSPIRE