A regular vacuum solution in 5D gravity on the principal bundle with the U (1) structural group is proposed as a 4D wormhole. This solution has two null hypersurfaces where an interchange of the sign of some 5D metric components happens. For a 4D observer living on the base of this principal bundle this is a wormhole with two asymptotically flat Lorentzian (Euclidean) spacetimes connected by a ...

The induced 4d gravity on a brane world is analyzed. The case of a thick brane is considered and the unexpected appearance of a new threshold scale, much larger than the thickness scale is found. In cases of phenomenological interest, this new length scale turns out to be in the submillimeter range. The effect of R corrections, both in the bulk and on the brane, is also studied. It is shown tha...

We show that the empty five-dimensional solutions of Davidson-Sonnenschtein-Vozmediano, Phys. Rev. D32 (1985)1330, in the " old " Kaluza-Klein gravity, under appropriate interpretation can generate an ample variety of cosmological models in 4D, which include the higher-dimensional modifications to general relativity predicted by " modern " versions of noncompactified 5D gravity as, e.g., induce...

We review the results of arXiv:hep-th/0703190, on brane induced gravity (BIG) in 6D. Among a large diversity of regulated codimension-2 branes, we find that for near-critical tensions branes live inside very deep throats which efficiently compactify the angular dimension. In there, 4D gravity first changes to 5D, and only later to 6D. The crossover from 4D to 5D is independent of the tension, b...

I review recent work toward constructing, via five-dimensional holographic duals, fourdimensional theories in which spin-2 states (gravitons) are emergent. The basic idea is to extend to gravity model-building the applications of holographic duality to phenomenology construction.

Warped extra dimension claims remarkable success: solving the hierarchy problem; explaining hierarchies in particle phenomenology; yielding standard cosmology, plus interesting nonstandard scenarios. Yet it has marked shortcomings: we over-rely on a single toy model, Randall-Sundrum; we treat matter and gravity in an ad hoc, asymmetric way; and we conceptualize integrated 4D effective field the...

Large-distance modification of gravity may be the mechanism for solving the cosmological constant problem. A simple model of the large-distance modification — four-dimensional (4D) gravity with the hard mass term— is problematic from the theoretical standpoint. Here we discuss a different model, the brane-induced gravity, that effectively introduces a soft graviton mass. We study the issues of ...

It is formulated a new ’anholonomic frame’ method of constructing exact solutions of Einstein equations with off–diagonal metrics in 4D and 5D gravity. The previous approaches and results [1–4] are summarized and generalized as three theorems which state the conditions when two types of ansatz result in integrable gravitational field equations. There are constructed and analyzed different class...