Modified Gravity and Cosmology

Advances in atomic physics, such as cooling and trapping of atoms and molecules and developments in frequency metrology, have added orders of magnitude to the precision of atom-based clocks and sensors. Applications extend beyond atomic physics and this article reviews using these new techniques to address important challenges in physics and to look for variations in the fundamental constants, search for interactions beyond the standard model of particle physics, and test the principles of general relativity.

Search for New Physics with Atoms and Molecules

Non-conventional cosmology from a brane-universe

Brane cosmological evolution in a bulk with cosmological constant

Kaluza-Klein gravity

Kaluza-Klein theory is developed starting from the simplest example in which a single extra spatial dimension is compactified to a circle, and a single Abelian gauge field emerges in four dimensions from the higher-dimensional metric. This is generalised to greater dimensionality whence non-Abelian gauge groups may be obtained, and possible mechanisms for achieving the compactification of the extra spatial dimensions are discussed. The spectrum of particles appearing in four dimensions is discussed with particular emphasis on the spectrum of light fermions, and the constraints arising from cancellation of anomalies when explicit higher-dimensional gauge fields are present are studied. Cosmological aspects of these theories are described, including possible mechanisms for cosmological inflation, and relic heavy particles. Finally, an introductory account of Kaluza-Klein supergravity is given leading towards superstring theory.

https://iopscience.iop.org/article/10.1088/0034-4885/50/9/001/pdf

D Bailin

Papers

Kaluza-Klein theories