Carlos Pastor Marcos: Cosmology from asymptotically safe Proca theories

Effective field theories for cosmology offer a powerful framework to investigate the dynamics of space–time and address longstanding open puzzles. In this work, we initiate a programme to analyse the ultraviolet completion of vector–tensor quantum field theories within the asymptotic safety paradigm, focusing on generalised Proca theories with a vector condensate. This enables us to assess whether a consistent fundamental UV completion exists and to constrain the set of viable infrared scenarios. Using the non–perturbative functional renormalisation group, we identify several fixed points, including Proca–type candidates, and, among them, a particularly remarkable one with four relevant directions: two associated with gravity and two induced by matter. This provides evidence for the non–perturbative renormalisability of vector–tensor theories. We further outline how the resulting UV critical surface constrains late–time cosmology.