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Nuclear Theory·nucl-th

Tuesday·July 14, 2020

13 papers—5 primary·8 cross-listed

All13Primary5Cross-lists8
  1. 01

    [Submitted on 11 Jul 2020]

    matter and its stability

    J. Hrtánková🇨🇿 · M. Schäfer🇨🇿 · J. Mareš🇨🇿 · A. Gal🇮🇱 · E. Friedman🇮🇱 · N. Barnea🇮🇱

    We performed calculations of nuclear systems composed solely of hyperons, aiming at exploring the possibility of existence of absolutely stable matter. We considered interaction strengths compatible with the binding energy given by the interaction model by Yamazaki and Akaishi [1]. We found that the binding energy per saturates at values well below 100 MeV for mass number . The matter is thus highly unstable against strong interaction decay.

    Comments:
    Proceedings of HADRON2019, 16 - 21 August 2019, Guilin, China, to appear in International Journal of Modern Physics A
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2007.05829 [pdf]
    2 citations
  2. 02

    [Submitted on 13 Jul 2020]

    Prolate-to-oblate transition and backbending along the yrast line induced by quasiparticle alignment

    Fang-Qi Chen🇨🇳 · Q. B. Chen🇩🇪

    The yrast lines in Kr isotopes with , 44, and 46 are investigated in a beyond mean field framework with both prolate-oblate coexistence and quasiparticle alignment taken into account. Quasiparticle orbitals with high- and low- on the oblate side are shown to be responsible for the sharp backbending observed in Kr, by driving the yrast shape from prolate to oblate. This suggests that quasiparticle alignment may not be neglected in the investigation of the shape evolution along the yrast line.

    Comments:
    6 pages, 5figiures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2007.06217 [pdf]
    PLB(2020)·1 citation
  3. 03

    [Submitted on 13 Jul 2020]

    Impurity Lattice Monte Carlo for Hypernuclei

    Dillon Frame🇩🇪 · Timo A. Lähde🇩🇪 · Dean Lee🇺🇸 · Ulf-G. Meißner🇩🇪

    We consider the problem of including hyperons into the ab initio framework of nuclear lattice effective field theory. In order to avoid large sign oscillations in Monte Carlo simulations, we make use of the fact that the number of hyperons is typically small compared to the number of nucleons in the hypernuclei of interest. This allows us to use the impurity lattice Monte Carlo method, where the minority species of fermions in the full nuclear Hamiltonian is integrated out and treated as a worldline in Euclidean projection time. The majority fermions (nucleons) are treated as explicit degrees of freedom, with their mutual interactions described by auxiliary fields. This is the first application of the impurity lattice Monte Carlo method to systems where the majority particles are interacting. Here, we show how the impurity Monte Carlo method can be applied to compute the binding energy of the light hypernuclei. In this exploratory work we use spin-independent nucleon-nucleon and hyperon-nucleon interactions to test the computational power of the method. We find that the computational effort scales approximately linearly in the number of nucleons. The results are very promising for future studies of larger hypernuclear systems using chiral effective field theory and realistic hyperon-nucleon interactions, as well as applications to other quantum many-body systems.

    Comments:
    10 pages, 4 figures, some more explanations and references, version published in EPJA
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Computational Physics (physics.comp-ph)
    arXiv:
    2007.06335 [pdf]
    EPJA(2020)·22 citations
  4. 04

    [Submitted on 13 Jul 2020]

    Probing chemical freeze-out criteria in relativistic nuclear collisions with coarse grained transport simulations

    Tom Reichert🇩🇪 · Gabriele Inghirami🇫🇮 · Marcus Bleicher🇩🇪

    We introduce a novel approach based on elastic and inelastic scattering rates to extract the hyper-surface of the chemical freeze-out from a hadronic transport model in the energy range from E AGeV to GeV. For this study, the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model combined with a coarse-graining method is employed. The chemical freeze-out distribution is reconstructed from the pions through several decay and re-formation chains involving resonances and taking into account inelastic, pseudo-elastic and string excitation reactions. The extracted average temperature and baryon chemical potential are then compared to statistical model analysis. Finally we investigate various freeze-out criteria suggested in the literature. We confirm within this microscopic dynamical simulation, that the chemical freeze-out at all energies coincides with GeV, while other criteria, like and fm are limited to higher collision energies.

    Comments:
    9 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2007.06440 [pdf]
    EPJA(2020)·20 citations
  5. 05

    [Submitted on 13 Jul 2020]

    Radius and equation of state constraints from massive neutron stars and GW190814

    Yeunhwan Lim · Anirban Bhattacharya · Jeremy W. Holt · Debdeep Pati

    Motivated by the unknown nature of the compact object in the binary merger event GW190814, we study the maximum neutron star mass based on constraints from low-energy nuclear physics, neutron star tidal deformabilities from GW170817, and simultaneous mass-radius measurements of PSR J0030+045 from NICER. Our prior distribution is based on a combination of nuclear modeling valid in the vicinity of normal nuclear densities together with the assumption of a maximally stiff equation of state at high densities, a choice that enables us to probe the connection between observed heavy neutron stars and the transition density at which conventional nuclear physics models must break down. We demonstrate that a modification of the highly uncertain supra-saturation density equation of state beyond 2.64 times normal nuclear density is required in order for chiral effective field theory models to be consistent with current neutron star observations and the existence of neutron stars. We also show that the existence of very massive neutron stars strongly impacts the radii of neutron stars (but not necessarily the radii of neutron stars), which further motivates future NICER radius measurements of PSR J1614-2230 and PSR J0740+6620.

    Comments:
    6 pages, 4 figures, revised figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    2007.06526 [pdf]
    PRC(2021)·60 citations

Affiliations

first authorsco-authorsvia INSPIRE