论文标题
广义的异形Horndeski理论：宇宙学扰动和一致的物质耦合
Generalized disformal Horndeski theories: cosmological perturbations and consistent matter coupling
论文作者
论文摘要
可逆变换是研究无鬼标量张量理论的有用工具。通过对Horndeski理论的可逆变形转换进行更高衍生的概括，我们构建了一类新的无鬼标量张量理论，我们将其概括为概括性的非正式Horndeski理论。具体而言，这些理论超出了二次/立方DHOST类。我们探索宇宙学的扰动，以识别一个子类，其中引力波以光的速度传播，并阐明缺乏张量和标量扰动的幽灵/梯度不稳定性的条件。我们还研究了物质领域可以始终如一地与这些理论耦合的条件，而无需引入不必要的额外自由度。
Invertible disformal transformations are a useful tool to investigate ghost-free scalar-tensor theories. By performing a higher-derivative generalization of the invertible disformal transformation on Horndeski theories, we construct a novel class of ghost-free scalar-tensor theories, which we dub generalized disformal Horndeski theories. Specifically, these theories lie beyond the quadratic/cubic DHOST class. We explore cosmological perturbations to identify a subclass where gravitational waves propagate at the speed of light and clarify the conditions for the absence of ghost/gradient instabilities for tensor and scalar perturbations. We also investigate the conditions under which a matter field can be consistently coupled to these theories without introducing unwanted extra degrees of freedom.
