f(R,L_m)引力中太初核合成的可行性
Viability of Big Bang Nucleosynthesis in $f(R,L_m)$ Gravity
- Dibrugarh University（迪布鲁加尔大学）
- Silapathar College（西拉帕塔尔学院）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究分析f(R,L_m)引力下BBN约束的可行性，推导四种模型参数的严格约束，发现f(R,L_m)引力可适配原初元素丰度且不破坏早期宇宙动力学。
AI中文摘要：
我们研究f(R,L_m)引力下大爆炸核合成（Big Bang Nucleosynthesis, BBN）约束的可行性，其中引力拉格朗日量是里奇标量R和物质拉格朗日密度L_m的任意函数。我们通过分析氦-4（⁴He）的原初丰度以及中子-质子冻结温度的分数变化，对四种不同f(R,L_m)引力模型的基础模型参数推导了严格约束。结果表明，f(R,L_m)引力在BBN约束下仍保持可行性，其中冻结条件对参数空间提供最主要的约束，而⁴He丰度的约束则作为对修正膨胀速率的独立丰度水平一致性检验。综上，这些可行参数区域的存在表明，f(R,L_m)引力模型可成功适配原初元素丰度，且不会破坏标准早期宇宙动力学。
英文摘要：
We examine the viability of Big Bang Nucleosynthesis (BBN) constraints in $f(R,L_m)$ gravity, where the gravitational Lagrangian is an arbitrary function of the the Ricci scalar $R$ and matter Lagrangian density $L_m$. We derive stringent bounds on the underlying model parameters of four different $f(R,L_m)$ gravity models by examining both the primordial abundances of helium-4 ($^4\text{He}$) and the fractional variations in the neutron--proton freeze out temperature. Our results reveal that $f(R,L_m)$ gravity remains viable under the BBN constraints. With the freeze-out condition offering the most dominat constraint on the parameter space, whereas the bounds from $^4\text{He}$ abundance act as a separate abundance level consistency checks on the modified expansion rate. In summary, the presence of these feasible parameter regions demonstrates that $f(R,L_m)$ gravity models can successfully accommodate primordial element abundances without disrupting standard early Universe dynamics.
