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Nuclear Theory·nucl-th

Monday·December 13, 2021

11 papers—5 primary·6 cross-listed

All11Primary5Cross-lists6
  1. 01

    Hot neutron stars and their equation of state

    Jin-Biao Wei · G. F. Burgio · Ad. R. Raduta · H.-J. Schulze

    A set of microscopic, covariant density-functional, and non-relativistic Skyrme-type equations of state is employed to study the structure of purely nucleonic neutron stars at finite temperature. After examining the agreement with presently available astrophysical observational constraints, we find that the magnitude of thermal effects depends on the nucleon effective mass as well as on the stiffness of the cold equation of state. We evidence a fairly small but model-dependent effect of finite temperature on stellar stability that is correlated with the relative thermal pressure inside the star.

    nucl-thastro-ph.HEPRC(2021)·24 citations
  2. 02

    Cooper quartet correlations in infinite symmetric nuclear matter

    Yixin Guo🇯🇵 · Hiroyuki Tajima🇯🇵 · Haozhao Liang🇯🇵

    We investigate the quartet correlations in four-component fermionic systems at the thermodynamic limit within a variational many-body theory. The Bardeen-Cooper-Schrieffer (BCS)-type variational wave function is extended to the systems with the coexistence of pair and quartet correlations at zero temperature. Special attention is paid to the application of the present framework to an alpha-particle condensation in symmetric nuclear matter, where the coexistence of deuteron and alpha condensations is anticipated. We also discuss how physical properties, such as quasiparticle dispersion, can be modified by the pair and quartet correlations and show a hierarchical structure of in-medium cluster formations in infinite nuclear matter. The present results may also contribute to the interdisciplinary understanding of fermionic condensations beyond the BCS paradigm in many-body systems.

    nucl-thcond-mat.quant-gasquant-phPRC(2022)·15 citations
  3. 03

    Hybrid stars from a constrained equation of state

    Márcio Ferreira🇵🇹 · Renan Câmara Pereira🇵🇹 · Constança Providência🇵🇹

    We determine, within a meta-model, the properties of the nuclear matter equation of state (EoS) that allow for a phase transition to deconfinement matter. It is shown that the properties that define the isoscalar channel are the ones that are affected, in particular, a phase transition implies much larger values of the skewness and kurtosis. The effect of multi-quark interaction channels in the description of the quark phase in hybrid stars is also studied. NS properties, such as the mass and radius of the quark core, show an interplay dependence between the 8-quark vector and the 4-quark isovector-vector interactions. We show that low mass NS, , may already contain a quark core, and satisfy all existing NS observational constraints. We discuss the strangeness content of the quark core and its influence on the speed of sound.

    nucl-thastro-ph.HEhep-phEPJ Web Conf.(2022)·2 citations
  4. 04

    Determination of the symmetry energy from the neutron star equation of state

    Pedro Barata de Tovar🇵🇹 · Márcio Ferreira🇵🇹 · Constança Providência🇵🇹

    We analyze the uncertainties introduced in the determination of the neutron star matter proton fraction, in a range of densities close to the saturation density, if the cold -equilibrium neutron star matter equation of state (EoS) is known. In particular, we discuss the effect of neglecting the muon contribution and of considering that the energy density of nuclear matter is well described by taking only terms until second order in the proton-neutron asymmetry. It is shown that two types of uncertainties may be associated with the extraction of the symmetry energy from the -equilibrium equation of state: an overestimation if terms above the parabolic approximation on the asymmetry parameter are neglected, or an underestimation if the muon contribution is not considered. The effect of the uncertainty on the symmetric nuclear matter EoS on the determination of the proton fraction is discussed. It could be shown that the neutron star mass-radius curve is sensitive to the parabolic approximation on the asymmetry parameter.

    nucl-thastro-ph.HEhep-phPRD(2021)·23 citations
  5. 05

    and decay of the Be neutron halo ground state

    J. Okołowicz🇵🇱 · M. Płoszajczak🇫🇷 · W. Nazarewicz🇺🇸

    Beta-delayed proton emission from the neutron halo ground state of Be raised much attention due to the unusually high decay rate. It was argued that this may be due to the existence of a resonance just above the proton decay threshold. In this Letter, we use the lenses of real-energy continuum shell model to describe several observables including the Gamow-Teller rates for the -delayed and proton decays, and argue that, within our model, the large branching ratio cannot be reconciled with other data.

    nucl-thnucl-exJ.Phys.G(2022)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE