Holography in flipped AdS/$\mathbb{Z}$: Another approach to dS holography

Abstract

Motivated by the subtleties in the conventional dS/CFT correspondence, we explore analytic continuation as a constructive route to de Sitter holography. We show that quantum field theories in de Sitter space and in a spacetime that we call flipped $\mathrm{AdS}/\mathbb{Z}$ (fAdS) are related by analytic continuation. We then develop a holographic description of fAdS in terms of a boundary theory referred to as flipped CFT (fCFT). In particular, we construct the extrapolate dictionary for general asymptotically fAdS spacetimes and compute the holographic two-point functions, finding agreement with an independent derivation based on the conformal symmetry of fCFT. The analytic continuation relation between fAdS and dS further suggests that fCFT may provide a starting point for an alternative holographic description of de Sitter physics. As a nontrivial check of this picture, we show that the Cardy formula of fCFT$_2$ reproduces the Bekenstein--Hawking entropies of the cosmological horizons in both pure dS$_3$ and Kerr-dS$_3$.