Quark mean field model with pion and gluon corrections for Λ and Ξ0 hypernuclei and neutron stars

Abstract

Properties of Λ, Ξ 0 hypernuclei and neutron stars are investigated in quark mean field model with pion and gluon corrections. Firstly, u, d, and s quarks are confined by relativistic harmonic oscillator potentials to generate the baryons, like nucleon, Λ, Σ, and Ξ hyperons. The effects of pion-quark coupling and one-gluon exchange are considered perturbatively. Then, the baryons interact with each other through exchanging σ, ω, and ρ mesons between quarks in hypernuclei and nuclear matter. The strengths of confinement potentials for u, d, and s quarks are determined by the masses and radii of free baryons. The coupling constants between the quarks and mesons are fixed by the ground-state properties of several nuclei and single-hyperon potentials at nuclear saturation density, which arises three parameter sets for the coupling constants between mesons and quarks, named QMF-NK1S, QMF-NK2S, and QMF-NK3S. Compared to the results of previous quark mean field model without pion and gluon corrections, it is found that properties of Λ hypernuclei, i.e. the single Λ energies, are more consistent with the experimental observables. Properties of Ξ 0 hypernuclei are also calculated and compared with the results in previous quark mean field model. With these three parameter sets, the neutron stars containing hyperons are investigated through solving the Tolman-Oppenheimer-Volkoff equation. Maximum masses of neutron stars approach 2.1M ⊙ with hyperons and corresponding radii are around 13 km.

The $ΞN$ interaction constrained by recent $Ξ^-$ hypernuclei experiments

“…Once the values of B Ξ − (1p) were constrained, the only free parameter in the QMF model for Ξ − hypernuclei, g ωΞ will be fixed. The other coupling constants between mesons and baryons and the strengths of confinement potentials have been determined by the groundstate properties of finite nuclei and free baryon masses, in our previous works [31,32].…”

“…The baryons interact with each other through exchanging mesons and photons in quark mean-field (QMF) model [29][30][31][32]. The Lagrangian can be evaluated as,…”

Neutron star matter with Δ isobars in a relativistic quark model

“…This relativistic quark model has been successfully applied to various domains of nuclear and high energy physics including the baryon spectroscopy [30], electromagnetic form factors of nucleons [31], magnetic moments of the octet baryons [32], nucleon structure functions in deep inelastic scattering [33], symmetric [34] and asymmetric [35] nuclear matter. More recently this framework has been used to study the equation of state of neutron star matter with hyperon degrees of freedom and the properties of Λ and Ξ 0 hypernuclei [36,37]. Studies on the effect of the nucleon charge radius on the mass and radius of neutron stars [38] and developing an equation of state within the constraints set by GW170817 observations [39] are some other recent works undertaken using this model.…”

Single $Λ_c^+$ hypernuclei within quark mean-field model

“…Many phenomenological confinement potentials have been proposed, where the polynomial forms were widely used. In this work, we adopt a harmonic oscillator potential with a mixing scalar-vector structure [68][69][70][71],…”

“…The baryon-baryon interaction in nucleus is realized by exchanging the σ, ω, and ρ mesons between the quarks in different baryons. The QMF model has been successfully used to study the properties of normal nuclei, Λ, Ξ hypernuclei and neutron star after including the effects of pions and gluons at hadron level [67][68][69][70][71][72].…”