Critical gravity is a quadratic curvature gravity in four dimensions which

is ghost-free around the AdS background. Constructing a Vaidya-type exact solution,

we show that the area of a black hole defined by a future outer trapping horizon can

shrink by injecting a charged null fluid with positive energy density, so that a black hole

is no more a one-way membrane even under the null energy condition. In addition, the

solution shows that the Wald-Kodama dynamical entropy of a black hole is negative and

can decrease. These properties expose the pathological aspects of critical gravity at the

non-perturbative level.

is ghost-free around the AdS background. Constructing a Vaidya-type exact solution,

we show that the area of a black hole defined by a future outer trapping horizon can

shrink by injecting a charged null fluid with positive energy density, so that a black hole

is no more a one-way membrane even under the null energy condition. In addition, the

solution shows that the Wald-Kodama dynamical entropy of a black hole is negative and

can decrease. These properties expose the pathological aspects of critical gravity at the

non-perturbative level.

typ: | article |
---|---|

journal: | J. High Energy Phys. |

volume: | 06 |

pages: | 118 |

year: | 2018 |

pacs: | https://doi.org/10.1007/JHEP06(2018)118 |