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arXiv 1612.04097gr-qchep-th
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关于$2d$经典引力中的动力学和自由度的一个简短说明

A short note on dynamics and degrees of freedom in $2d$ classical gravity

Corinne de Lacroix, Harold Erbin

摘要:

我们评论的一些特殊性的问题与和没有Weyl不变性耦合到经典的$2d$爱因斯坦-希尔伯特引力的几个模型,特别是有关的自由度和动力学的计数。我们发现,理论的物质行动是外尔不变的一般有更多的自由度比行动没有不变性。这是由运动的度规方程的外尔不变性所得出的,与作用量的不变性无关。然后,我们研究了另一组模型与标量场和运动方程的解决方案是平凡的或不一致的。据我们所知,经典$2d$重力的这些方面还没有提出,当把它作为$4d$重力的玩具模型时,记住这些方面可能会很有趣。这篇文章的目的也是作为一个教学练习:我们的结果遵循标准方法,但我们强调更直接的计算。

英文摘要:

We comment on some peculiarities of matter with and without Weyl invariance coupled to classical $2d$ Einstein-Hilbert gravity for several models, in particular, related to the counting of degrees of freedom and on the dynamics. We find that theories where the matter action is Weyl invariant has generically more degrees of freedom than action without the invariance. This follows from the Weyl invariance of the metric equations of motion independently of the invariance of the action. Then, we study another set of models with scalar fields and show that solutions to the equations of motion are either trivial or inconsistent. To our knowledge, these aspects of classical $2d$ gravity have not been put forward and can be interesting to be remembered when using it as a toy model for $4d$ gravity. The goal of this note is also as a pedagogical exercise: our results follow from standard methods, but we emphasize more direct computations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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