### Abstract

I reconsider asymmetrically warped compactifications, in which time and space have different warp factors. I call such compactifications time warps if the bulk geometry has neither entropy nor temperature. I provide an example starting from an asymptotically AdS5 spacetime where the speed of light, measured in a fixed coordinate system, is larger near the boundary than it is deep in the interior. This example follows the general plan of earlier work on superconducting black holes. To obtain a normalizable, four-dimensional graviton, one can introduce a Planck brane whose action includes a wrong-sign Einstein-Hilbert term. The equation of state of the Planck brane has w <-1, which is a violation of the null energy condition. I show, in an almost dimension-independent fashion, that such a violation must occur in a static time warp geometry. Time warps of the type I describe provide an extra-dimensional description of boost invariance as an emergent symmetry in the infrared. High-energy violations of Lorentz symmetry, if confined to a strongly coupled unparticle sector dual to the time warp geometry, might manifest themselves through unusual kinematic constraints. As an example, I explain how modifications of unparticle phase space would affect the decay of a heavy particle into a light visible sector particle plus unparticle stuff.

Original language | English (US) |
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Article number | 20 |

Journal | Journal of High Energy Physics |

Volume | 2010 |

Issue number | 1 |

DOIs | |

State | Published - 2010 |

### All Science Journal Classification (ASJC) codes

- Nuclear and High Energy Physics

### Keywords

- Gauge-gravity correspondence
- Phenomenological models

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## Cite this

*Journal of High Energy Physics*,

*2010*(1), [20]. https://doi.org/10.1007/JHEP01(2010)020