Time warps

TL;DR

This paper explores novel asymmetrically warped compactifications called time warps, where time and space warp differently, potentially leading to emergent boost invariance and Lorentz symmetry violations detectable via unparticle physics.

Contribution

It introduces a new class of time warp geometries with zero entropy and temperature, and demonstrates their implications for emergent symmetries and Lorentz violations in higher-dimensional models.

Findings

Time warps can have a Planck brane with w < -1, violating null energy condition.

Such geometries suggest boost invariance as an emergent infrared symmetry.

Unparticle sector modifications could reveal high-energy Lorentz violations.

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 AdS_5 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.