论文标题
标准辐射主导的时代中高阶重力的精确解决方案
An exact solution of the higher-order gravity in standard radiation-dominated era
论文作者
论文摘要
我们报告说，辐射主导的ERA（RDE）宇宙的标准演变$ a \ propto t^{1/2} $是求解从包含$ b r^{ab} r_ {ab} r_ {ab} r_ {ab} r_ {ab} + c r^r^r^r^r^r {r^$ as an的第六阶重力场方程的足够条件用于空间平坦的辐射FLRW宇宙。借助$ r^{ab} r_ {ab} $和$ r^2 $模型，直至背景顺序和$ {r^{; c}}} _ {c} _ {c} $ for $ h = 1/（2t）$的消失属性，可以从特殊情况下获得一般案例的分析解决方案。这证明，即使在涉及高阶项的修改后重力理论中，标准宇宙进化也是有效的。这种背景解决方案在张量型扰动中的应用将复杂的方程式降低到引力波的标准二阶方程。我们讨论了在观测值中区分修饰的重力模型的可能方法，例如来自干扰宇宙的重力波和原始丰度。
We report that the standard evolution of radiation-dominated era (RDE) universe $a \propto t^{1/2}$ is a sufficient condition for solving a sixth order gravitational field equation derived from the Lagrangian containing $B R^{ab}R_{ab} + C R {R^{;c}}_{c}$ as well as a polynomial $f(R)$ for a spatially flat radiation FLRW universe. By virtue of the similarity between $R^{ab}R_{ab}$ and $R^2$ models up to the background order and of the vanishing property of ${R^{;c}}_{c}$ for $ H = 1/(2t)$, the analytical solution can be obtained from a special case to general one. This proves that the standard cosmic evolution is valid even within modified gravitational theory involving higher-order terms. An application of this background solution to the tensor-type perturbation reduces the complicated equation to the standard second order equation of gravitational wave. We discuss the possible ways to discriminate the modified gravity model on the observations such as the gravitational wave from the disturbed universe and primordial abundances.
