Partial Reduction and Cosmology at Defect Brane

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.

27+1 pages, 14 figures

References in corpus (3)

• Defect extremal surface as the holographic counterpart of Island formula
• Analytic Bootstrap in 2D Boundary Conformal Field Theory: Towards Braneworld Holography
• Effective Action, Spectrum and First Law of Wedge Holography