Dynamical dark energy: Scalar fields and running vacuum

Recent analyses in the literature suggest that the concordance Formula: see textCDM model with rigid cosmological term, Formula: see text may not be the best description of the cosmic acceleration. The class of “running vacuum models”, in which Formula: see text evolves with the Hubble rate, has been shown to fit the string of SNIa + BAO + H(z) + LSS + CMB data significantly better than the Formula: see textCDM. Here, we provide further evidence on the time-evolving nature of the dark energy (DE) by fitting the same cosmological data in terms of scalar fields. As a representative model, we use the original Peebles and Ratra potential, Formula: see text. We find clear signs of dynamical DE at Formula: see text c.l., thus reconfirming through a nontrivial scalar field approach the strong hints formerly found with other models and parametrizations.