High Energy Theory Group Seminar: Flat Spacetime Cosmology in a Scalar-Tensor Theory of Gravity

Abstract:

A scalar-tensor theory of gravity, linear in the scalar curvature, is formulated in which $G$, particle masses, and a cosmological constant are allowed to vary. The theory yields a flat and static cosmological model with time-independent angular scales. No flatness and horizon `problems' arise in this model; consequently, there is no need for an inflationary expansion phase. Lack of (global) evolutionary timescales implies that there are no cosmological coincidences, including the near equality of the energy densities of dark energy and dark matter.

Irrespective of the specifics of the model, it can be shown that the energy densities of dark energy ($\rho_{DE}$), dark matter ($\rho_{DM}$), and (non-relativistic) baryons ($\rho_{b}$), are related by $\rho_{DE}=2\rho_{DM}+\rho_{b}/2$, in good agreement with current observations, if DE and DM are associated with the kinetic and potential energy densities of the scalar fields.

Seminar Organizer: Shira Chapman