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Page curve for an evaporating Schwarzschild black hole in dimensionally reduced model of dilaton gravity

Stefan Đorđević and Voja Radovanović

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Phys. Rev. D 113, 105020 – Published 29 May, 2026

DOI: https://doi.org/10.1103/nc2z-hx6s

Abstract

We study entanglement entropy of quantum fields in a (1+1)-dimensional model of dilaton gravity derived from the four-dimensional Einstein-Hilbert action by dimensional reduction. Scalar matter is coupled to gravity, while the backreaction is included via the Polyakov-Liouville action. This theory exhibits both eternal and evaporating Schwarzschild black hole solutions. The fine-grained entropy in a collapse scenario is investigated by applying the “island rule” via the quantum extremal surface approach. We demonstrate that the fine-grained entropy of the Hawking radiation follows the Page curve, and therefore the evolution of the Hawking radiation is unitary.

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Phys. Rev. D 113, 105020– Published 29 May, 2026
  • Received 25 July 2025
  • Accepted 30 April 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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