See-Saw Modification of Gravity

TL;DR

This paper proposes a brane-world gravity model with a fundamental scale of 10^{-3} eV, predicting observable modifications at cosmological and sub-millimeter scales, testable by experiments and cosmological data.

Contribution

It introduces a new brane-world model with a low fundamental gravity scale, linking high-dimensional operators to observable gravity modifications at large and small scales.

Findings

Gravity is modified at the Hubble scale and around 0.1 mm.

The fundamental gravity scale is fixed at 10^{-3} eV.

Model predictions are testable via experiments and cosmology.

Abstract

We discuss a model in which the fundamental scale of gravity is restricted to 10^{-3} eV. An observable modification of gravity occurs simultaneously at the Hubble distance and at around 0.1 mm. These predictions can be tested both by the table-top experiments and by cosmological measurements. The model is formulated as a brane-world theory embedded in a space with two or more infinite-volume extra dimensions. Gravity on the brane reproduces the four-dimensional laws at observable distances but turns to the high-dimensional behavior at larger scales. To determine the crossover distance we smooth out the singularities in the Green's functions by taking into account softening of the graviton propagator due to the high-dimensional operators that are suppressed by the fundamental scale. We find that irrespective of the precise nature of microscopic gravity the ultraviolet and infrared scales of gravity-modification are rigidly correlated. This fixes the fundamental scale of gravity at 10^{-3} eV. The result persists for nonzero thickness branes.