Nuclear matter properties and neutron star structures from an extended linear sigma model
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arXiv
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| Format: | Preprint |
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2026
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| _version_ | 1866918451523616768 |
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| author | Ma, Yao |
| author_facet | Ma, Yao |
| contents | The properties of nuclear matter and the structures of neutron stars are analyzed with a baryonic extended linear sigma model in mean-field approximation, where the masses of baryons and mesons are generated via the spontaneous chiral symmetry breaking. The couplings between the iso-scalar scalar meson and nucleons, $g_{σNN}$, the iso-vector scalar meson and nucleons, $g_{a_0 NN}$, and the four-vector meson couplings play an important role in the properties of nuclear matter and neutron stars. The introduction of the $δ$ meson leads to a plateau structure of the symmetry energy, $E_{\rm sym}(n)$, at intermediate densities, which is crucial to the consistency of neutron skin thickness of $^{208}$Pb and the tidal deformability of a canonical neutron star. The explicit chiral symmetry breaking term is then introduced with a constant background field, $ξ$, which can be related to the current quark mass and thus the pion-nucleon sigma term, $σ_{πN}$. A negative $σ_{πN}$ leads to a stiffer EOS of neutron star matter and thus a larger maximum mass of neutron stars, but the value of $σ_{πN}$ needed to satisfy the astrophysical constraints is negative, not positive as the vacuum value. The study may provide insights into the running behaviors of the parameters in the low-energy effective model to give the density-dependent description for the EOS of neutron star matter. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_03849 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Nuclear matter properties and neutron star structures from an extended linear sigma model Ma, Yao Nuclear Theory The properties of nuclear matter and the structures of neutron stars are analyzed with a baryonic extended linear sigma model in mean-field approximation, where the masses of baryons and mesons are generated via the spontaneous chiral symmetry breaking. The couplings between the iso-scalar scalar meson and nucleons, $g_{σNN}$, the iso-vector scalar meson and nucleons, $g_{a_0 NN}$, and the four-vector meson couplings play an important role in the properties of nuclear matter and neutron stars. The introduction of the $δ$ meson leads to a plateau structure of the symmetry energy, $E_{\rm sym}(n)$, at intermediate densities, which is crucial to the consistency of neutron skin thickness of $^{208}$Pb and the tidal deformability of a canonical neutron star. The explicit chiral symmetry breaking term is then introduced with a constant background field, $ξ$, which can be related to the current quark mass and thus the pion-nucleon sigma term, $σ_{πN}$. A negative $σ_{πN}$ leads to a stiffer EOS of neutron star matter and thus a larger maximum mass of neutron stars, but the value of $σ_{πN}$ needed to satisfy the astrophysical constraints is negative, not positive as the vacuum value. The study may provide insights into the running behaviors of the parameters in the low-energy effective model to give the density-dependent description for the EOS of neutron star matter. |
| title | Nuclear matter properties and neutron star structures from an extended linear sigma model |
| topic | Nuclear Theory |
| url | https://arxiv.org/abs/2603.03849 |