标题： 原初宇宙学的涌现型宇宙来自修改引力：使用遗传算法进行重构和现象优化 显示英文标题

标题： Primordial Cosmology of an Emergent-like Universe from Modified Gravity: Reconstruction and Phenomenology Optimization with a Genetic Algorithm

摘要： 在本工作中，我们考虑在$f(R)$引力背景下一种变异涌现宇宙场景的实现。 我们使用文献中已知的重建技术，并在大曲率近似下找到再现特定变异涌现宇宙标度因子的真空$f(R)$的近似形式。 正如我们所展示的，在变异涌现宇宙场景中，哈勃视界最初收缩，宇宙经历了一个加速膨胀时期。 在微扰理论方法中，标量和张量曲率扰动可以用通常用于暴胀现象学的表征指数$\epsilon_i , i=1,3,4$表示，我们提取了标量和张量扰动的谱指数，以及用扰动指数表示的张量与标量比值。 我们使用一种强大的遗传算法深入研究模型的参数空间，该空间由多个自由参数量化，以研究当该模型与普朗克 2018 数据比较时的可行性。 我们还研究了我们发现的真空$f(R)$引力对大爆炸核合成的影响。 显示英文摘要

摘要： In this work we consider the realization of a variant emergent Universe scenario in the context of $f(R)$ gravity. We use well-known reconstruction techniques existing in the literature, and we find the approximate form of the vacuum $f(R)$ that reproduces the specific variant emergent Universe scale factor in the large curvature approximation. As we show, in the variant emergent Universe scenario, the Hubble horizon shrinks primordially and the Universe undergoes in an accelerated expansion era. In a perturbation theory approach, the scalar and tensor curvature perturbations can be expressed in terms of the phenomenological indices $\epsilon_i , i=1,3,4$, usually used for inflationary phenomenology, and we extract the spectral indices for the scalar and tensor perturbations, along with the tensor-to-scalar ratio expressed in terms of the perturbation indices. Using a powerful genetic algorithm we investigate in depth the parameter space of the model, quantified by several free parameters, in order to study the viability of the model when this is compared with the Planck 2018 data. We also investigate the implications of the vacuum $f(R)$ gravity we found on the Big Bang nucleosynthesis.