Seminar by Carlos Garcia Garcia (CIEMAT): “The status of single scalar field dark energy”

Title: The status of single scalar field dark energy

Speaker: Carlos Garcia Garcia (CIEMAT)

Venue & Time: Red Room / 15:00

Abstract: We are entering an exciting era in cosmology, with tantalizing hints of dynamical dark energy. While current data are not yet sufficient to determine its nature, they may already provide clues about its microphysical origin. Assuming the latest observations (DESI BAO + SNe Ia + CMB) are correct, I will show that the evidence for dynamical dark energy remains mild and depends on prior choices. Furthermore, assuming dark energy arises from a single scalar field, I will show that current data mildly favor models with a negative squared mass and either a non-minimal coupling to gravity or a non-standard kinetic term. These scenarios lead to distinct signatures in the ISW effect, the growth of cosmic structure, and Solar System tests of gravity. I will discuss why current probes are not yet sufficient to distinguish between them and the prospects for uncovering the microphysical nature of dark energy with upcoming observations.