论文标题
扩展重力宇宙学中的重力问题
The gravitino problem in Extended Gravity cosmologies
论文作者
论文摘要
重力宇宙学的框架中研究了重力问题。特别是，我们考虑了$ f（r）$重力，这是希尔伯特 - 因斯坦动作的最自然延伸，以及$ f（\ cal t）$ gravility，teleparallool等价重力的扩展。由于在这些理论中，与标准的$λ$ CDM宇宙学相比，宇宙的扩展定律进行了修改，因此可以修改颗粒的热历史。我们表明，$ f（r）$型号允许避免重力的较晚。特别是，我们发现，对于表征$ f（r）$模型的参数的适当选择，重力丰度与重新加热的温度无关。在$ f（\ cal t）$重力的背景下也达到了类似的行为。从这个角度来看，我们可以得出结论，对标准的一般相对性（以及触发平行的一般相对性等效）的几何校正可以改善宇宙学和超出标准粒子标准模型之外的统一理论的缺点。
The gravitino problem is investigated in the framework of Extended Gravity cosmologies. In particular, we consider $f(R)$ gravity, the most natural extension of the Hilbert-Einstein action, and $f(\cal T)$ gravity, the extension of teleparallel equivalent gravity. Since in these theories the expansion laws of the Universe are modified, as compared to the standard $Λ$CDM cosmology, it follows that also the thermal history of particles gets modified. We show that $f(R)$ models allow to avoid the late abundance of gravitinos. In particular, we found that for an appropriate choice of the parameters characterizing the $f(R)$ model, the gravitino abundance turns out to be independent of the reheating temperature. A similar behavior is achieved also in the context of $f(\cal T)$ gravity. In this perspective, we can conclude that geometric corrections to standard General Relativity (and to Teleparallel Equivalent of General Relativity) can improve shortcomings both in cosmology and in unified theories beyond the Standard Model of particles.
