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arXiv 1108.2277gr-qchep-th
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二次曲率理论中的无Bel-Robinson张量

No Bel-Robinson Tensor for Quadratic Curvature Theories

S. Deser, J. Franklin

摘要:

我们试图把GR的协变守恒的Bel-Robinson张量B_{mnab} ~ RR和它最近的拓扑大质量三阶导数对应张量B ~ RDR推广到二次曲率作用.两个非常不同的模型,目前的利益:四阶D=3“新的质量”,和二阶D>4 Lanczos-Lovelock,重力检查。根据维数,这里的候选项变为B ~ DRDR+RRR。对于D=3模型,在线性化极限下确实存在守恒的BdRdR.然而,尽管有过多的可用的立方项,B不能扩展到完整的理论。D>4的模型甚至不能在平坦空间线性化,因为它们的场方程是曲率平方的;它们也没有可行的B,即使我们包括宇宙学或爱因斯坦项,允许对所得的dS真空线性化,这个事实仍然存在。这些结果是一个意想不到的,如果不是唯一的,线性化不稳定的例子。

英文摘要:

We attempt to generalize the familiar covariantly conserved Bel-Robinson tensor B_{mnab} ~ R R of GR and its recent topologically massive third derivative order counterpart B ~ RDR, to quadratic curvature actions. Two very different models of current interest are examined: fourth order D=3 "new massive", and second order D>4 Lanczos-Lovelock, gravity. On dimensional grounds, the candidates here become B ~ DRDR+RRR. For the D=3 model, there indeed exist conserved B ~ dRdR in the linearized limit. However, despite a plethora of available cubic terms, B cannot be extended to the full theory. The D>4 models are not even linearizable about flat space, since their field equations are quadratic in curvature; they also have no viable B, a fact that persists even if one includes cosmological or Einstein terms to allow linearization about the resulting dS vacua. These results are an unexpected, if hardly unique, example of linearization instability.

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