标题： 从引力的有效场论中去除虚假的自由度 显示英文标题

标题： Removing spurious degrees of freedom from EFT of gravity

摘要： 在引力的有效场论方法中，广义相对论的拉格朗日密度通过在黎曼张量及其导数的更高阶协变项进行了补充。 表面上看，这些项将导致运动方程具有更高的导数，并且会引入超出广义相对论范围的额外自由度。 这似乎与有效场论的目标相冲突，有效场论的目标是以现有低能自由度的形式编码紫外修正。 在这里，我们针对广义相对论加上一个三次项黎曼张量的情况，应用了一种基于作用量的去除虚假自由度的方法。 在我们工作的范围内，所得的约化理论形式为最小修改引力，这是一种修改引力理论的类，它传播的是无质量的自旋-2引力子，但在短距离内由于时间微分同胚的变形而表现出优先框架。 我们的工作表明，这类理论可以被理解为引力的有效理论，捕捉未知紫外物理的影响。 显示英文摘要

摘要： In the effective field theory approach to gravity, the Lagrangian density for general relativity is supplemented by generally covariant terms of higher order in the Riemann tensor and its derivatives. At face value, these terms will result in higher derivative equations of motion and additional degrees of freedom beyond those of general relativity. This is seemingly at odds with the goal of effective field theory which is to encode ultraviolet corrections in terms of existing low energy degrees of freedom. Here we apply an action-based procedure for the removal of spurious degrees of freedom for the case of general relativity supplemented by a term cubic in the Riemann tensor. To the order we work in, the resulting reduced theory takes the form of minimally modified gravity, which is a class of modified gravity theories that propagate just the massless spin-2 graviton, but exhibit a preferred frame at short distances due to a deformation of time diffeomorphisms. Our work suggests that this class of theories can be understood as an effective theory of gravity, capturing effects of unknown ultraviolet physics.