Bound Dark Energy: Towards understanding the nature of the Dark Energy

We present a brief overview of the current status of cosmology. In particular, we will concentrate on the origin of the accelerating expansion of our Universe,  one of the most important open questions in physics. Its solution requires new physics, either  by postulating  a new kind of energy density the Dark Energy (DE) or modifying General Relativity.  The  concordance model in cosmology ($\Lambda$CDM)  assumes a cosmological constant $\Lambda$  as DE and has an excellent agreement with the observations. However, there is  no understanding of  the  origin nor magnitude  of $\Lambda$  and hence of why and when the Universe accelerates. Here we  will present a DE model,  as a natural extension of the Standard Model  of particle physics (SM),  with  no free parameters. Our DE corresponds to a quintessence field and has an excellent  fit with current cosmological data  improving  the Baryon Acoustic Oscillations (BAO) measurements,  specially designed to determine  the dynamics of DE, with a likelihood ratio of 2.1 compared to  LCDM, showing that a non constant DE is dynamically preferred. Finally, we present the cosmological properties of our model at a background and perturbation level.