发表机构
GLA University; King Faisal University; Amity University Patna（GLA大学; 费萨尔国王大学; 阿密蒂大学巴特那分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究在正则化4DEGB引力中，用微扰QCD状态方程求解夸克星结构，发现高曲率修正提升最大质量，硬分支超观测上限，软分支需大耦合。
AI 中文摘要
我们在正则化四维爱因斯坦-高斯-博内（4DEGB）引力框架下，采用Fraga、Kurkela和Vuorinen [1]的微扰QCD状态方程，研究了自束缚夸克星的平衡结构和稳定性。该状态方程由单一重整化尺度参数$X$参数化，不含有效袋常数，并完全通过夸克物质压力消失来定义恒星表面。我们针对$X \in \{3, 4\}$和高斯-博内耦合$\alpha \in \{0, 1, 10\}\\,\mathrm{km}^2$，求解了从4DEGB引力的标量-张量表述推导出的修正托尔曼-奥本海默-沃尔科夫方程。对于软状态方程（$X = 3$），最大质量从$2.0431\\,M_\odot$（广义相对论）增加到$\alpha = 10\\,\mathrm{km}^2$时的$2.5013\\,M_\odot$，且仅后者进入PSR~J0952$-$0607质量带。对于硬状态方程（$X = 4$），广义相对论基线已给出$3.0415\\,M_\odot$，所有构型均超过GW190814次质量体和PSR~J0952$-$0607约束。所有构型在最大质量处的致密度$C = M/R$范围从$0.2531$到$0.3123$，始终远低于Buchdahl界限。声速平方的径向分布证实，对于所有参数选择，$c_s^2 < 1/3$在恒星内部逐点成立，确立了夸克物质在最大质量恒星内部保持亚共形和因果性。这些结果表明，4DEGB引力中的高曲率修正系统地增强了微扰QCD夸克星可支撑的最大质量，其中硬（$X = 4$）分支即使在广义相对论水平也已超过目前观测到的最致密致密天体，而软（$X = 3$）分支需要$\alphaGB \sim 10\\,\mathrm{km}^2$才能接近这些阈值。
英文摘要
We investigate the equilibrium structure and stability of selfbound quark stars in the framework of regularized four-dimensional Einstein--Gauss--Bonnet (4DEGB) gravity, employing the perturbative QCD equation of state of Fraga, Kurkela and Vuorinen [1]. The equation of state, parameterised by a single renormalization-scale parameter $X$, contains no effective bag constant and defines the stellar surface entirely through the vanishing of the quark-matter pressure. We solve the modified Tolman-Oppenheimer--Volkoff equations derived from the scalar--tensor formulation of 4DEGB gravity for $X \in \{3, 4\}$ and Gauss--Bonnet coupling $α\in \{0, 1, 10\}\,\mathrm{km}^2$. For the soft EOS ($X = 3$), the maximum mass increases from $2.0431\,M_\odot$ (GR) to $2.5013\,M_\odot$ at $α= 10\,\mathrm{km}^2$, with only the latter entering the PSR~J0952$-$0607 mass band. For the stiff EOS($X = 4$), the GR baseline already yields $3.0415\,M_\odot$, and all configurations exceed both the GW190814 secondary mass and the PSR~J0952$-$0607 constraint. The compactness $C = M/R$ at maximum mass ranges from $0.2531$ to $0.3123$ across all configurations, remaining well below the Buchdahl bound throughout. Radial profiles of the squared speed of sound confirm that $c_s^2 < 1/3$ holds pointwise throughout the stellar interior for all parameter choices, establishing that the quark matter remains sub-conformal and causal inside the maximum-mass star. These results demonstrate that higher-curvature corrections in 4DEGB gravity systematically enhance the maximum supported mass of perturbative QCD quark stars, with the stiff ($X = 4$) branch already exceeding the most massive compact objects currently observed even at the GR level, while the soft ($X = 3$) branch requires $\alphaGB \sim 10\,\mathrm{km}^2$ to approach those thresholds.
Comments14 pages, 7 figures
