Higgs inflation: Connecting Particle Physics, Gravity, and Cosmology

Cosmic inflation provides an explanation for the primordial fluctuations that seeded galaxies and large-scale structure, but its underlying physical mechanism remains unknown. One intriguing candidate is the Higgs field, which gives mass to elementary particles such as electrons. With a suitable coupling to gravity, this same field could also drive the accelerated expansion of the early Universe.

In this talk, I will present selected results connecting the theoretical foundations of Higgs inflation to its cosmological predictions. A central question is whether we can reliably describe the evolution of the Universe throughout inflation and its subsequent reheating. I will introduce a geometric perspective on the interactions between the Higgs field and gravity, which helps identify the energy range in which our calculations remain reliable, independently of how the theory is written. I will also discuss the Higgs–(R^2) model, in which an additional scalar degree of freedom associated with gravity can extend this range. Its inflationary and reheating dynamics illustrate how addressing questions of theoretical consistency can affect our understanding of the early Universe, including the connection between its thermal history and predictions for the cosmic microwave background.