The Interplay of Symmetry Energy Uncertainties, Nonlinear σ−δ Coupling, and Dark Matter in Neutron Star Macroscopic Properties
Abstract
The poorly constrained density dependence of the nuclear symmetry energy introduces significant uncertainties in the equation of state (EOS) of dense nuclear matter and, consequently, in neutron-star properties. We systematically investigate how uncertainties in the symmetry energy Esym and its slope L at saturation density n0 affect NS properties within the relativistic mean-field (RMF) framework, including the effects of nonlinear σ-δ coupling and possible admixture of dark matter(DM) . For fixed Esym(n0) and L(n0), we find that the σ-δ coupling with gσδ=−0.004 induces an abnormal softening of the EOS, which simultaneously increasing the maximum NS mass and reducing the stellar radius and tidal deformability. A similar behavior is found in the presence of DM with Fermi momentum kFDM=50 MeV at Esym(n0)=36 MeV. In this case, the RMF EOS satisfies the tidal-deformability constraint from GW170817. We further find that the surface curvature of NSs is strongly correlated with the stiffness of Esym, with softer symmetry energy corresponding to larger surface curvature. Our results also indicate that the behavior of Esym around n0 is mainly governed by isoscalar rather than isovector parameters.
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BibTeX
@misc{feng2026interplay,
title = {{The Interplay of Symmetry Energy Uncertainties, Nonlinear $σ-δ$ Coupling, and Dark Matter in Neutron Star Macroscopic Properties}},
author = {Zhaohui Feng and Xiaoxuan Zhai and Shuangxuan Chen and Defu Hou},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.08628},
eprint = {2609.08628},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.08628},
}
RIS
TY - UNPB
TI - The Interplay of Symmetry Energy Uncertainties, Nonlinear σ−δ Coupling, and Dark Matter in Neutron Star Macroscopic Properties
AU - Zhaohui Feng
AU - Xiaoxuan Zhai
AU - Shuangxuan Chen
AU - Defu Hou
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.08628
UR - https://arxiv.org/abs/2609.08628
AB - The poorly constrained density dependence of the nuclear symmetry energy introduces significant uncertainties in the equation of state (EOS) of dense nuclear matter and, consequently, in neutron-star properties. We systematically investigate how uncertainties in the symmetry energy E_sym and its slope L at saturation density n_0 affect NS properties within the relativistic mean-field (RMF) framework, including the effects of nonlinear σ-δ coupling and possible admixture of dark matter(DM) . For fixed E_sym(n_0) and L(n_0), we find that the σ-δ coupling with g_σδ=−0.004 induces an abnormal softening of the EOS, which simultaneously increasing the maximum NS mass and reducing the stellar radius and tidal deformability. A similar behavior is found in the presence of DM with Fermi momentum k_F^DM=50 MeV at E_sym(n_0)=36 MeV. In this case, the RMF EOS satisfies the tidal-deformability constraint from GW170817. We further find that the surface curvature of NSs is strongly correlated with the stiffness of E_sym, with softer symmetry energy corresponding to larger surface curvature. Our results also indicate that the behavior of E_sym around n_0 is mainly governed by isoscalar rather than isovector parameters.
ER -