title: Opening up extra dimensions at ultralarge scales.
abstract: The standard picture of viable higher-dimensional theories is that direct manifestations of extra dimensions occur at short distances only, whereas long-distance physics is effectively four-dimensional. We show that this is not necessarily true in models with infinite extra dimensions. As an example, we consider a five-dimensional scenario with three 3-branes in which gravity is five dimensional at both short- and very long-distance scales, with conventional four-dimensional gravity operating at intermediate length scales. A phenomenologically acceptable range of validity of four-dimensional gravity extending from microscopic to cosmological scales is obtained without strong fine-tuning of parameters.
authors.affiliation: Centre for Particle Theory, Durham University, South Road, Durham, DH1 3LE, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Gregory
authors.forename: V A
authors.initials: VA
authors.lastname: Rubakov
authors.forename: S M
authors.initials: SM
authors.lastname: Sibiryakov