Towards a realistic Kaluza-Klein cosmology

Brane cosmology in an arbitrary number of dimensions

“…From now on, we drop the tildes in the metric coefficients and time coordinate above. This is the product of a cosmological 4d spacetime with an internal sphere with time-dependent radius, in which matter is allowed to propagate, as is familiar from traditional KaluzaKlein cosmology [48][49][50][51]. We now show, using the same reasoning as in D = 5, why dark radiation is no longer uniquely defined from the assumption of 3d homogeneity and isotropy, and not even after assuming spherical symmetry around the brane.…”

Kaluza-Klein gravity

“…An important step in Kaluza-Klein cosmology was the demonstration that shrinking extra dimensions could transfer entropy into the four-dimensional universe, providing a new way to solve the horizon and flatness problems [221,282], although many (∼40) extra dimensions were required [283]. Inflation itself has also been incorporated directly in compactified Kaluza-Klein theories [284,285], and indeed "Kaluza-Klein inflation" has burgeoned into a sub-field of its own [286].…”

Expanding universe and dynamical compactification using Yang-Mills instantons

“…Our analysis indicates that the Yang-Mills instantons in internal space can act as an anti-gravitating matter source in our four-dimensional Universe. An accelerating expansion from and a dynamical compactification of extra dimensions are an old idea explored in many literatures [16,17,18] (see also Chapter 11.4 in [4]) and similar ideas using monopoles and instantons in extra dimensions have appeared in [19,20]. This paper is organized as follows.…”