Dark Matter and Dark Energy from a single scalar field

The strong CP problem was solved by Peccei & Quinn by introducing axions, which are a viable candidate forDM. Here the PQ approach is modified so to yield also Dark Energy (DE), which arises in fair proportions,without tuning any extra parameter. DM and DE arise from a single scalar field and, in the present ecpoch,are weakly coupled. Fluctuations have a fair evolution. The model is also fitted to WMAP release, using aMCMC technique, and performs as well as LCDM, coupled or uncoupled Dynamical DE. Best–fit cosmologicalparameters for different models are mostly within 2–σ level. The main peculiarity of the model is to favor highvalues of the Hubble parameter.