论文标题
$ f（r，t）$重力中的大爆炸核合成和熵演变
Big Bang Nucleosynthesis and Entropy Evolution in $f(R,T)$ Gravity
论文作者
论文摘要
本文专门用于限制$ f（r，t）= r +χt$重力模型的模型参数$χ$，通过使用来自大爆炸核合成的约束。我们在$ -0.14κ^{2} \ leqχ\ leq0.84κ^{2} $（其中$κ^{2} = \ frac {8πg} {c^{4} $）的范围内求解字段方程并约束$χ$。锂7。我们发现氦4和氘的丰富性与理论预测一致，但是锂问题仍然存在于$ f（r，t）$重力模型。我们还研究了辐射和尘埃宇宙的约束参数空间的熵演变。我们报告说，当辐射主导的宇宙的$χ= 0 $时，熵是恒定的，而对于尘埃宇宙，熵会随着时间而增加。我们终于使用约束来表明$χ$对冷暗物质歼灭横截面的影响微不足道。
The present article is devoted to constrain the model parameter $χ$ for the $f(R,T)= R + χT$ gravity model by employing the constraints coming from big bang nucleosynthesis. We solve the field equations and constrain $χ$ in the range $-0.14 κ^{2} \leq χ\leq 0.84 κ^{2}$ (where $κ^{2} = \frac{8 πG}{c^{4}}$) from the primordial abundances of light elements such as helium-4, deuterium and lithium-7. We found the abundances of helium-4 and deuterium agrees with theoretical predictions, however the lithium problem persists for the $f(R,T)$ gravity model. We also investigate the evolution of entropy for the constrained parameter space of $χ$ for the radiation and dust universe. We report that entropy is constant when $χ= 0$ for the radiation dominated universe, whereas for the dust universe, entropy increases with time. We finally use the constraints to show that $χ$ has negligible influence on the cold dark matter annihilation cross section.
