## Abstract

We explore the constraints boundary causality places on the allowable Gauss-Bonnet gravitational couplings in asymptotically AdS spaces, specifically considering spherical black hole solutions. We additionally consider the hyperbolicity properties of these solutions, positing that hyperbolicity-violating solutions are sick solutions whose causality properties provide no information about the theory they reside in. For both signs of the Gauss-Bonnet coupling, spherical black holes violate boundary causality at smaller absolute values of the coupling than planar black holes do. For negative coupling, as we tune the Gauss-Bonnet coupling away from zero, both spherical and planar black holes violate hyperbolicity before they violate boundary causality. For positive coupling, the only hyperbolicity-respecting spherical black holes which violate boundary causality do not do so appreciably far from the planar bound. Consequently, eliminating hyperbolicity-violating solutions means the bound on Gauss-Bonnet couplings from the boundary causality of spherical black holes is no tighter than that from planar black holes.

Original language | English (US) |
---|---|

Article number | 135003 |

Journal | Classical and Quantum Gravity |

Volume | 34 |

Issue number | 13 |

DOIs | |

State | Published - Jun 5 2017 |

Externally published | Yes |

## Keywords

- causality
- Gauss-Bonnet gravity
- higher curvature gravity
- hyperbolicity

## ASJC Scopus subject areas

- Physics and Astronomy (miscellaneous)