论文标题
非分类ricci型palatini理论的稳定性
Stability of non-degenerate Ricci-type Palatini theories
论文作者
论文摘要
我们研究了重力作用对Riemann Tensor的三个第一痕迹的任意代数依赖性的理论的稳定性：RICCI张量，共同张量和同型曲率张量。我们共同称它们为ricci型张量。我们允许任意耦合至关重要。我们考虑连接不受限制的情况，以及假定扭转或非金属度消失的情况。我们发现Ricci型张量的哪些组合导致Minkowski和Flrw空间周围以及幽灵时产生新的自由度。除了有两个新向量的两个先前已知的案例外，具有新的自由度的理论都没有健康。我们发现，投影性不变性不是理论无鬼魂的足够条件。
We study the stability of theories where the gravitational action has arbitrary algebraic dependence on the three first traces of the Riemann tensor: the Ricci tensor, the co-Ricci tensor, and the homothetic curvature tensor. We collectively call them Ricci-type tensors. We allow arbitrary coupling to matter. We consider the case when the connection is unconstrained, and the cases when either torsion or non-metricity is assumed to vanish. We find which combinations of Ricci-type tensors lead to new degrees of freedom around Minkowski and FLRW space, and when there are ghosts. None of the theories with new degrees of freedom are healthy, except for two previously known cases where there is a single new vector. We find that projective invariance is not a sufficient condition for a theory to be ghost-free.
