论文标题
在低衍生背景上的幽灵凝结和Ostrogradskian不稳定
Ghost condensation and Ostrogradskian instability on low derivative backgrounds
论文作者
论文摘要
我们展示了具有较高衍生物的新一类交互项，这些术语可以添加到每个低衍生物的真实标量中，以使理论是退化的，并且运动方程仍然是二阶的。与以前的设置相反，消除幽灵的必要约束也具有明显的身体动机：它们始终强加和保留真实标量的低衍生动力学作为背景，其上面是这些较高衍生的术语引起的波动，是变性术语的变化。我们在两步处方中总结了这些受约束的无幽灵真实标量的设置。与某些具有一阶导数相互作用的模型与深色能量和通货膨胀应用的模型相反，这些理论必须具有约束的二阶衍生衍生式自相互作用，并没有改变传播的速度，而野外方程的影响锥也不是由低衍生性背景规定的，这也是消除幽灵的必不可少的。因此，避免了前者的潜在超浮肿问题。
We show a new class of interaction terms with higher derivatives that can be added to every low derivative real scalar, such that the theory is degenerate, and the equation of motion remains of second order. In contrast to previous setups, the necessary constraints that eliminate the ghosts also have a clear physical motivation: they impose and preserve at all times the low derivative dynamics of the real scalar as a background, on top of which, the fluctuations induced by these higher derivative terms are degenerate, and ghost-free. We summarize the setup for these constrained ghost-free real scalars in a two-step prescription. In contrast to some models with first-order derivative interactions with applications for dark energy and inflation, these theories with necessarily constrained second-order derivative self-interactions do not modify the speed of propagation, neither the cone of influence for the field equations, which are prescribed by the low derivative background that is also essential to eliminate the ghost; hence, avoiding the potential superluminality issues of the former.
