Higher Order Clockwork Gravity

TL;DR

This paper introduces a higher order generalisation of the clockwork mechanism within multigravity theories, producing a spectrum with a weakly coupled massless graviton and TeV-scale massive modes, with potential implications for hierarchy and dark matter.

Contribution

It develops a novel higher order clockwork multigravity model with no hierarchies in the potential, featuring a unique spectrum of graviton modes and asymmetric conformal factors.

Findings

Massless graviton couples weakly to matter exponentially.

Presence of TeV-scale massive graviton modes with TeV couplings.

Potential applications to hierarchy problem and dark matter.

Abstract

We present a higher order generalisation of the clockwork mechanism starting from an underlying non-linear multigravity theory with a single scale and nearest neighbour ghost-free interactions. Without introducing any hierarchies in the underlying potential, this admits a family of Minkowski vacua around which massless graviton fluctuations couple to matter exponentially more weakly than the heavy modes. Although multi-diffeomorphisms are broken to the diagonal subgroup in our theory, an asymmetric distribution of conformal factors in the background vacua translates this diagonal symmetry into an asymmetric shift of the graviton gears. In particular we present a TeV scale multigravity model with ${\cal O}(10)$ sites that contains a massless mode whose coupling to matter is Planckian, and a tower of massive modes starting at a TeV mass range and with TeV strength couplings. This suggests a possible application to the hierarchy problem as well as a candidate for dark matter.