Published for SISSA by Springer Received: May 28, 2020 Accepted: June 15, 2020 Published: July 3, 2020 Islands in asymptotically flat 2D gravity JHEP07(2020)022 Thomas Hartman,a Edgar Shaghouliana and Andrew Stromingerb aDepartment of Physics, Cornell University, Ithaca, New York, U.S.A. bDepartment of Physics, Harvard University, Cambridge, MA, U.S.A. E-mail:
[email protected],
[email protected],
[email protected] Abstract: The large-N limit of asymptotically flat two-dimensional dilaton gravity cou- pled to N free matter fields provides a useful toy model for semiclassical black holes and the information paradox. Analyses of the asymptotic information flux as given by the entanglement entropy show that it follows the Hawking curve, indicating that information is destroyed in these models. Recently, motivated by developments in AdS/CFT, a semi- classical island rule for entropy has been proposed. We define and compute the island rule entropy for black hole formation and evaporation in the large-N RST model of dilaton gravity and show that, in contrast, it follows the unitary Page curve. The relation of these two observations, and interesting properties of the dilaton gravity island rule, are discussed. Keywords: 2D Gravity, Black Holes, Models of Quantum Gravity ArXiv ePrint: 2004.13857 Open Access, c The Authors. https://doi.org/10.1007/JHEP07(2020)022 Article funded by SCOAP3. Contents 1 Introduction1 2 Review of the RST model4 2.1 Large-N action and equation of motion4 2.2 Solutions6 2.2.1 Linear dilaton vacuum6 JHEP07(2020)022