Dark Matter, Dark Energy and the solution of the strong CP problem

Abstract

The strong CP problem was solved by Peccei & Quinn by introducing axions, a viable candidate for Dark Matter (DM). Here the PQ approach is modified so to yield also Dark Energy (DE). DM and DE arise, in fai proportions, from a single scalar field, without tuning any extra parameter. In the present epoch, they are weakly coupled. Fluctuations have a fair evolution. The model is also fitted to the WMAP1 release, using a Markov Chain Monte Carlo technique, and performs as well as $\hat{I}›$CDM, coupled or uncoupled DE. Best--fit cosmological parameters for different models are mostly within 2--$\ddot{I}ƒ$ level. Here, the main peculiarity of the model is to favor high values of the Hubble parameter.

Proceeding of the workshop dsu2006, "The Dark Side of th Universe", Madrid, June 20-24, 2006