Dynamical Vacuum Energy in the Universe: a real alternative to the rigid cosmological term

Author: Adria Gomez



Abstract: The presence of a non-null cosmological term in Einstein's field equations became essential after the discovery of the universe's speeding up about twenty years ago. Now, Lambda is a key ingredient of the so-called concordance model. But despite its success, I will show that a large class of cosmological scenarios with dynamical vacuum energy density are able to improve the phenomenological status of the former. These "running vacuum models" consists of a nonvanishing constant term and a series of powers of the Hubble rate. Such generic structure is potentially linked to the quantum field theoretical description of the expanding Universe. An overall fit to the cosmological observables SNIa+BAO+H(z)+LSS+BBN+CMB shows that the class of RVM's appears significantly more favored than the LCDM, at an unprecedented level \sim 4.2\sigma.