English

Homogeneous Instantons in Bigravity

High Energy Physics - Theory 2015-04-14 v2 Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology

Abstract

We study homogeneous gravitational instantons, conventionally called the Hawking-Moss (HM) instantons, in bigravity theory. The HM instantons describe the amplitude of quantum tunneling from a false vacuum to the true vacuum. Corrections to General Relativity (GR) are found in a closed form. Using the result, we discuss the following two issues: reduction to the de Rham-Gabadadze-Tolley (dRGT) massive gravity and the possibility of preference for a large ee-folding number in the context of the Hartle-Hawking (HH) no-boundary proposal. In particular, concerning the dRGT limit, it is found that the tunneling through the so-called self-accelerating branch is exponentially suppressed relative to the normal branch, and the probability becomes zero in the dRGT limit. As far as HM instantons are concerned, this could imply that the reduction from bigravity to the dRGT massive gravity is ill-defined.

Keywords

Cite

@article{arxiv.1411.6769,
  title  = {Homogeneous Instantons in Bigravity},
  author = {Ying-li Zhang and Misao Sasaki and Dong-han Yeom},
  journal= {arXiv preprint arXiv:1411.6769},
  year   = {2015}
}

Comments

20 pages, 2 figures, comments and references added

R2 v1 2026-06-22T07:11:10.747Z