| Speaker: | Thomas Steingasser (U Madrid) |
|---|---|
| Title: | Precision unitarity calculations in inflationary models |
| Date (JST): | Wed, Nov 11, 2026, 13:30 - 15:00 |
| Place: | Seminar Room A |
| Abstract: |
Inflationary models involving scalar fields with nonminimal couplings to gravity provide an attractive framework for describing the early Universe. However, their theoretical consistency is often challenged by the breakdown of perturbative unitarity, which can introduce an inevitable sensitivity to unknown ultraviolet (UV) physics. Traditionally, the associated cutoff scales have been estimated using order-of-magnitude arguments, which may become unreliable in regions of parameter space characterized by small scalar self-couplings, such as critical Higgs inflation. I will present a systematic framework for precision unitarity calculations in inflationary models. By analyzing the full scattering matrix and carefully accounting for phase-space factors, we obtain precise results of the perturbative unitarity cutoff. I will discuss the qualitative differences between single-field and multifield models, the role of nonminimal couplings and scalar self-interactions, and the implications of different formulations of gravity. As an application, I will revisit critical Higgs inflation, where the established order-of-magnitude estimates become too inaccurate. I will examine its compatibility with electroweak measurements, cosmic microwave background observations, and perturbative unitarity. This example illustrates how precision unitarity calculations can provide important insights into the theoretical consistency and predictive power of inflationary models. |
