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Nuclear Theory·nucl-th

Wednesday·June 8, 2022

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 01

    Delta baryons in neutron stars

    Kauan D. Marquez🇧🇷 · Helena Pais🇧🇷 · Débora P. Menezes🇵🇹 · Constança Providência🇵🇹

    By applying a relativistic mean-field description of neutron star matter with density dependent couplings, we analyse the properties of two different matter compositions: nucleonic matter with delta baryons and nucleonic matter with hyperons and delta baryons. The delta-meson couplings are allowed to vary within a wide range of values obtained by experimental data, while the hyperon-meson couplings are fitted to hypernuclear properties. Neutron star properties with no deconfinement phase transition are studied. It is verified that many models are excluded because the effective nucleon mass becomes zero before the maximum mass configuration is attained. Hyperon-free with delta-dominated composition compact stars are possible, the deltic stars. It is found that with a convenient choice of parameters the existence of deltic stars with 80% of delta baryons at the center of the star is possible. However, the presence of hyperons lowers the delta baryon fraction to values below 20% at the center and below 30% at 2-3 saturation densities. It is discussed that in the presence of delta baryons, the hyperon softening is not so drastic because deltas couple more strongly to the -meson, and the stiffness of the equation of state is determined by the -dominance at high densities. The speed of sound reflects very well this behavior. The compactness of the pulsar RX J0720.4-3125 imposes and favors .

    nucl-thastro-ph.HEhep-phPRC(2022)·33 citations
  2. 02

    Triaxiality induced monopole-quadrupole-hexadecupole coupling in the isoscalar giant resonances for

    Xuwei Sun · Jie Meng

    The isoscalar giant resonances for are studied by the quasiparticle finite amplitude method based on the covariant density functional theory. In addition to the well-known monopole-quadrupole coupling that splits the isoscalar giant monopole resonance in axially deformed nuclei, a monopole-quadrupole-hexadecupole coupling is identified in the triaxially deformed nucleus , leading to the emergence of a distinct resonance peak at the low energy side of the isoscalar monopole strength function. The transition density of the triaxiality induced resonance peak shows a strong interplay among monopole, quadrupole, and hexadecupole vibrations. The resonance peak responses to monopole, quadrupole, and hexadecupole perturbations simultaneously, which could be regarded as a fingerprint of the triaxiality in .

    nucl-thPRC(2022)·5 citations
  3. 03

    Combined theoretical analysis of the parity-violating asymmetry for Ca and

    Paul-Gerhard Reinhard · Xavier Roca-Maza · Witold Nazarewicz

    The recent experimental determination of the parity violating asymmetry in Ca and Pb at Jefferson Lab is important for our understanding on how neutrons and protons arrange themselves inside the atomic nucleus. To better understand the impact of these measurements, we present a rigorous theoretical investigation of in Ca and Pb and assess the associated uncertainties. We complement our study by inspecting the static electric dipole polarizability in these nuclei. The analysis is carried out within nuclear energy density functional theory with quantified input. We conclude that the simultaneous accurate description of in Ca and Pb cannot be achieved by our models that accommodate a pool of global nuclear properties, such as masses and charge radii, throughout the nuclear chart, and describe -- within one standard deviation -- the experimental dipole polarizabilities in these nuclei.

    nucl-thnucl-exPRL(2022)·121 citations
  4. 04

    Nuclear Transparencies in a Relativistic Glauber Model

    Wim Cosyn · Jan Ryckebusch

    In light of the recent Jefferson Laboratory (JLab) data for the nuclear transparencies, calculations, obtained in a relativistic multiple scattering Glauber approximation, are discussed. The shell-separated C transparencies are shown and it is concluded that the -shell nucleons are 75\% more transparent than the -shell ones. The presented comparisons between the calculations made here and the current data show no clear indication for the onset of color transparency when implemented within the color diffusion model with standard parameters.

    nucl-thnucl-exMDPI Physics(2022)·1 citation

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first authorsco-authorsvia INSPIRE