论文标题
观察指数中F（R）重力中非单个反弹的自下而上的重建
Bottom-up reconstruction of non-singular bounce in F(R) gravity from observational indices
论文作者
论文摘要
我们在f（r）重力中弹跳宇宙学的背景下应用自下而上的重建技术，其中起点是可观察数量的合适ansatz（例如光谱索引或张量与标量比），而不是hubble参数的先验形式。在通货膨胀的情况下，假定慢速条件保持真实，因此观察指数在慢速参数方面具有一般表达式，例如，f（r）通胀中的张量与标量比可以表示为$ r =48ε_f^2 $，$ε_f= $ε_f= = $ε_f= = - \ frac {1} {h_f^2} \ frac {dh_f} {dt_f} $和$ h_f $，$ t_f $分别是哈勃参数，宇宙时间。但是，在弹跳的宇宙学（例如在F（R）重力理论中），通常不满足缓慢的条件，因此可观察的数量没有任何一般表达方式，无论F（r）的形式如何，都将保持真实的状态。因此，为了在F（r）弹跳模型中应用自下而上的重建过程，我们使用F（R）和标量探望模型之间的共形对应关系，其中当前上下文中的共形因子以某种方式选择，以使其导致标量调节器框架中的通货膨胀场景。由于标量和张量的扰动在共形转换下保持不变的原因，标量调节膨胀模型的可观察到的生存能力证实了共同连接的F（r）弹跳模型的生存能力。在这些参数的启发下，我们在这里直接从相应标量探望模型的可观察指标中构造了一个可行的非单明反弹。
We apply the bottom-up reconstruction technique in the context of bouncing cosmology in F(R) gravity, where the starting point is a suitable ansatz of observable quantity (like spectral index or tensor to scalar ratio) rather than a priori form of Hubble parameter. In inflationary scenario, the slow roll conditions are assumed to hold true, and thus the observational indices have general expressions in terms of the slow-roll parameters, as for example the tensor to scalar ratio in F(R) inflation can be expressed as $r = 48ε_F^2$ with $ε_F = -\frac{1}{H_F^2}\frac{dH_F}{dt_F}$ and $H_F$, $t_F$ are the Hubble parameter, cosmic time respectively. However, in the bouncing cosmology (say in F(R) gravity theory), the slow-roll conditions are not satisfied, in general, and thus the observable quantities do not have any general expressions that will hold true irrespective of the form of F(R). Thus, in order to apply the bottom-up reconstruction procedure in F(R) bouncing model, we use the conformal correspondence between F(R) and scalar-tensor model where the conformal factor in the present context is chosen in a way such that it leads to an inflationary scenario in the scalar-tensor frame. Due to the reason that the scalar and tensor perturbations remain invariant under conformal transformation, the observable viability of the scalar-tensor inflationary model confirms the viability of the conformally connected F(R) bouncing model. Motivated by these arguments, here we construct a viable non-singular bounce in F(R) gravity directly from the observable indices of the corresponding scalar-tensor inflationary model.
