Cosmology from asymptotically safe Proca theories

TL;DR

This paper explores the ultraviolet completion of generalized Proca theories in cosmology using the asymptotic safety approach, identifying fixed points that suggest non-perturbative renormalisability and constraining late-time cosmological scenarios.

Contribution

It initiates a program to analyze the UV behavior of vector-tensor theories in cosmology, finding fixed points that support their fundamental consistency.

Findings

Identified several fixed points including a notable one with four relevant directions.

Provided evidence for the non-perturbative renormalisability of vector-tensor theories.

Outlined how UV fixed points constrain late-time cosmology.

Abstract

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.