论文标题
dhost弹跳
DHOST Bounce
论文作者
论文摘要
我们提出了一类新的非弹跳宇宙学，没有不稳定性，使用单个标量场与退化高阶标量（DHOST）理论的框架内的重力结合。在这种类型的情况下，在标量调整器和Horndeski/Galileon理论的框架中，在非弹跳宇宙学中广泛存在的梯度不稳定性被DHOST引入的新操作员的效果消除了，这是由于后来将它们带来扰动的分散性关系的修改。因此，我们的结果表明，当原始扰动通过反弹阶段演变时，这种类型的弹跳场景确实存在一个漏洞，因此，理论上的{\ it no-go}定理是Horndeski/Galileon Theories的非发源物宇宙学的非发明弹跳术语，可以精心挑选出来。
We present a new class of nonsingular bounce cosmology free from instabilities, using a single scalar field coupled to gravity within the framework of the Degenerate Higher-Order Scalar-Tensor (DHOST) theories. In this type of scenarios, the gradient instability that widely exists in nonsingular bounce cosmologies in the framework of scalar-tensor and Horndeski/Galileon theories is removed by the effects of new operators introduced by the DHOST, due to the modification that they later bring about to the dispersion relation of perturbations. Hence, our results demonstrate that there is indeed a loophole for this type of bounce scenarios to be free from pathologies when primordial perturbations evolve through the bounce phase, and thus the theoretical {\it no-go} theorem for nonsingular bounce cosmology of Horndeski/Galileon theories can be delicately evaded in DHOST extensions.
