PaperPanorama
FAQ

Nuclear Theory·nucl-th

Friday·August 5, 2022

10 papers—6 primary·4 cross-listed

All10Primary6Cross-lists4
  1. 01

    [Submitted on 4 Aug 2022]

    Partial-wave expansion of three-baryon interactions in chiral effective field theory

    M. Kohno🇯🇵 · H. Kamada🇯🇵 · K. Miyagawa🇯🇵

    An expression of partial wave expansion of three-baryon interactions in chiral effective field theory is presented. The derivation follows the method by Hebeler et al. [Phys. Rev. C{\bf 91}, 044001 (2015)], but the final expression is more general. That is, a systematic treatment of the higher-rank spin-momentum structure of the interaction becomes possible. Using the derived formula, a -deuteron folding potential is evaluated. This information is valuable for inferring the possible contribution of the three-baryon forces to the hypertriton as the basis of further studies by sophisticated Faddeev calculations. A microscopic understanding of three-baryon forces together with two-body interactions is essential for the description of hypernuclei and neutron-star matter.

    Comments:
    7 pages, 4 figures. The version accepted for publication in Phys. Rev. C. The results of the numerical calculation have been revised
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2208.02388 [pdf]
    PRC(2022)·8 citations
  2. 02

    [Submitted on 4 Aug 2022]

    The matrices of elastic -C scattering at low energies in effective field theory

    Shung-Ichi Ando (Sunmoon U.)

    The elastic -C scattering at low energies for is studied in effective field theory. We discuss the construction of the matrices of elastic -C scattering in terms of the amplitudes of sub-threshold bound and resonant states of O, which are calculated from the effective Lagrangian. The parameters appearing in the matrices are fitted to the phase shift data below the -N breakup threshold energy, and we find that the phase shifts are well described within the theory.

    Comments:
    28 pages, 13 figures; version accepted for publication in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2208.02404 [pdf]
    PRC(2023)·12 citations
  3. 03

    [Submitted on 4 Aug 2022]

    Exploring medium mass nuclei using effective chiral nucleon-nucleon interactions

    Sota Yoshida

    In the past decades, it has been shown that the three-body force is necessary for a fully microscopic understanding of nuclear many-body systems, and thus efficient schemes for storing and utilizing three-body matrix elements have been developed. However, three-body matrix elements still demand a lot of memory and/or storage and it readily exceeds the limitation of the state-of-the-art supercomputers. We explore the possibility of mimicking the effects of three-body forces in medium-mass region, especially lower shell, by density-dependent effective nucleon-nucleon interactions combining with a modern family of chiral nucleon-nucleon interaction and an uncertainty quantification on the coupling constants. We found that some effective nucleon-nucleon potentials give decent description of ground state energies, but also systematic underestimation in charge radii and deficiencies relevant to the -shell region.

    Comments:
    6 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2208.02464 [pdf]
    2 citations
  4. 04

    [Submitted on 4 Aug 2022]

    Proton number cumulants and correlation functions from hydrodynamics and the QCD phase diagram

    Volodymyr Vovchenko🇺🇸 · Volker Koch🇺🇸 · Chun Shen🇺🇸

    We analyze the behavior of (net-)proton number cumulants in central collisions of heavy ions across a broad collision energy range by utilizing hydrodynamic simulations. The calculations incorporate essential non-critical contributions to proton fluctuations such as repulsive baryonic core and exact baryon number conservation. The experimental data are consistent with non-critical physics at collision energies GeV. The data from STAR and HADES Collaborations at lower collision energies indicate an excess of (multi-)proton correlations over the non-critical reference. This observation is discussed in the context of different mechanisms, including the possibility of a critical point in the baryon-rich region of the QCD phase diagram.

    Comments:
    6 pages, 2 figures, contribution to the proceedings of Quark Matter 2022
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2208.02571 [pdf]
    Acta Phys.Polon.Supp.(2023)·1 citation
  5. 05

    [Submitted on 4 Aug 2022]

    Surface energy of magnetized superconducting matter in the neutron star cores

    D. N. Kobyakov

    In this paper, an effective field theory for proton superconductor (SC) interacting with neutron superfluid (SF), both with scalar order parameters, is developed and applied to the surface energy (SE) of a magnetized SC body in neutron stars (NS). Essentially, the SE studied here differs from the nuclear SE: here, the proton SF density decays to zero while the total proton density is constant across the surface. Interactions between the condensates are parameterized phenomenologically and their effects determined from calculations of a planar SE as the ranges of parameters are varied. The critical Ginzburg-Landau (GL) parameter which renders the SE equal to zero is found analytically by noting that in a system with vanishing SE the thermodynamic critical MF is equivalent to the upper critical MF. In the case of weak coupling, is shown to be a linear function of SF-SF density-density coupling, in agreement with the earlier results based on asymptotic intervortex interactions. Numerical simulations corroborate our analytical predictions. Coupling due to the mixed term arising from a scalar product of gradients of the SF densities, which had been considered in the earlier literature, is seen to have practically no effect on the superconductivity type. However, this coupling does produce a frozen wave packet of the SF neutron density localized at the surface. It is shown that the leading contribution from the gradient coupling arises from a novel mixed quantum pressure term, but still does not affect the planar SE. The present calculations provide an initial map of superconductivity types in the phenomenological effective field theory and will serve as a landmark for future studies, which require microscopic calculations of the coupling parameters introduced here phenomenologically.

    Comments:
    15 pages, 3 figures. Published 9 October 2020
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    2208.02738 [pdf]
    PRC(2020)·3 citations
  6. 06

    [Submitted on 4 Aug 2022]

    From moments of the distribution function to hydrodynamics: The non-conformal case

    Sunil Jaiswal🇮🇳 · Jean-Paul Blaizot🇫🇷 · Rajeev S. Bhalerao🇮🇳 · Zenan Chen🇨🇳 · Amaresh Jaiswal🇮🇳 · Li Yan🇨🇳

    We study the one-dimensional boost-invariant Boltzmann equation in the relaxation-time approximation using special moments of the distribution function for a system with a finite particle mass. The infinite hierarchy of moments can be truncated by keeping only the three lowest moments that correspond to the three independent components of the energy-momentum tensor. We show that such a three-moment truncation reproduces accurately the exact solution of the kinetic equation after a simple renormalization that takes into account the effects of the neglected higher moments. We derive second-order Israel-Stewart hydrodynamic equations from the three-moment equations, and show that, for most physically relevant initial conditions, these equations yield results comparable to those of the three-moment truncation, albeit less accurate. We attribute this feature to the fact that the structure of Israel-Stewart equations is similar to that of the three-moment truncation. In particular, the presence of the relaxation term in the Israel-Stewart equations, yields an early-time regime that mimics approximately the collisionless regime. A detailed comparison of the three-moment truncation with second-order non-conformal hydrodynamics reveals ambiguities in the definition of second-order transport coefficients. These ambiguities affect the ability of Israel-Stewart hydrodynamics to reproduce results of kinetic theory.

    Comments:
    26 pages, 11 figures (manuscript now in PRC format)
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2208.02750 [pdf]
    PRC(2022)·38 citations

Affiliations

first authorsco-authorsvia INSPIRE