The Power of Brane-Induced Gravity

TL;DR

This paper shows that a brane-localized four-dimensional Einstein term in a five-dimensional, flat spacetime with one compact extra dimension can render an astronomically large extra dimension compatible with four-dimensional gravity on the brane. Gravity on the brane is dominated by a massless zero-mode while the heavy Kaluza-Klein states couple weakly, suppressing the vDVZ discontinuity and relaxing high-energy constraints. The authors derive the resulting static potential, KK spectrum, and tensor structure, and identify two viable parameter regimes: (i) an astronomical $R$ with $R/r_c \lesssim 10^{-4}$ (potentially yielding TeV-scale fundamental gravity) and (ii) a sub-millimeter $R$ where heavy KK modes are heavily suppressed, relaxing star-cooling and cosmological bounds. They also discuss possible microscopic origins of the crossover scale and implications for sub-millimeter dimensions, highlighting observational tests via planetary dynamics and precision gravity experiments.

Abstract

We study the role of the brane-induced graviton kinetic term in theories with large extra dimensions. In five dimensions we construct a model with a TeV-scale fundamental Planck mass and a {\it flat} extra dimension the size of which can be astronomically large. 4D gravity on the brane is mediated by a massless zero-mode, whereas the couplings of the heavy Kaluza-Klein modes to ordinary matter are suppressed. The model can manifest itself through the predicted deviations from Einstein theory in long distance precision measurements of the planetary orbits. The bulk states can be a rather exotic form of dark matter, which at sub-solar distances interact via strong 5D gravitational force. We show that the induced term changes dramatically the phenomenology of sub-millimeter extra dimensions. For instance, high-energy constraints from star cooling or cosmology can be substantially relaxed.