Nonexistence of Extremal de Sitter Black Rings

@article{Khuri2017NonexistenceOE,
  title={Nonexistence of Extremal de Sitter Black Rings},
  author={M. Khuri and E. Woolgar},
  journal={arXiv: High Energy Physics - Theory},
  year={2017}
}
We show that near-horizon geometries in the presence of a positive cosmological constant cannot exist with ring topology. In particular, de Sitter black rings with vanishing surface gravity do not exist. Our result relies on a known mathematical theorem which is a straightforward consequence of a type of energy condition for a modified Ricci tensor, similar to the curvature-dimension conditions for the $m$-Bakry-\'Emery-Ricci tensor. 
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