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arXiv · 1602.07546

Variational Principle for Gravity with Null and Non-null boundaries: A Unified Boundary Counter-term

Krishnamohan Parattu·Sumanta Chakraborty·T. Padmanabhan
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Abstract

It is common knowledge that the Einstein-Hilbert action does not furnish a well-posed variational principle. The usual solution to this problem is to add an extra boundary term to the action, called a counter-term, so that the variational principle becomes well-posed. When the boundary is spacelike or timelike, the Gibbons-Hawking-York counter-term is the most widely used. For null boundaries, we had proposed a counter-term in a previous paper. In this paper, we extend the previous analysis and propose a counter-term that can be used to eliminate variations of the "off-the-surface" derivatives of the metric on any boundary, regardless of its spacelike, timelike or null nature.

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Krishnamohan Parattu, Sumanta Chakraborty, T. Padmanabhan. 2016-02-23. Variational Principle for Gravity with Null and Non-null boundaries: A Unified Boundary Counter-term. https://doi.org/10.1140/epjc%2Fs10052-016-3979-y

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