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arXiv · 2112.13782

Partial Reduction and Cosmology at Defect Brane

Zhi Wang·Zekun Xu·Shuyan Zhou·Yang Zhou
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Abstract

Partial reduction is a Randall-Sundrum reduction for only part of the AdS region between finite tension brane and zero tension brane. This is interesting in AdS/BCFT where the AdS bulk contains a defect brane. We employ partial reduction for a AdS bulk with a brane evolving as a $2d$ Friedmann-Robertson-Walker (FRW) cosmology and demonstrate the equivalence between defect extremal surface and island formula for a large subregion fine grained entropy in boundary CFT. We then move to higher dimensions and demonstrate the existence of $4d$ massless graviton on AdS$_4$ brane in partial reduction. We also propose a partial reduction for a $4d$ FRW cosmology at defect brane and obtain the Newton constant by computing boundary entropy.

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Zhi Wang, Zekun Xu, Shuyan Zhou, Yang Zhou. 2021-12-27. Partial Reduction and Cosmology at Defect Brane. https://doi.org/10.1007/jhep05(2022)049

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