Title: Lectures on Higgs Inflation and Unitarity
Speaker: Dr. Minxi He (IBS, Daejeon, CTPU)
Abstract: I review the Higgs inflation and its variants in different formalisms of gravity in this series of lectures, and discuss the (p)reheating process and the related unitarity issues from which I extend my discussion to one particular UV-extension of Higgs inflation with a curvature squared term.
I start from a brief review of the current status of inflationary cosmology and motivate the study of Higgs inflation given that its predictions are within the best-fit region of the observational data as the Starobinsky model.
Then, I present the details of inflationary predictions and (p)reheating process as well as the related unitarity issue in the Higgs inflation with Einstein gravity, namely the metric Higgs inflation, as an important starting point for later discussion.
The strong coupling issue in this model is shown, due to the production of gauge bosons during preheating.
Motivated to have a perturbative UV-extension, I show the presence of an $ R^2 $ term as one solution to UV-extend the metric Higgs inflation.
Alternatively, a variant of Higgs inflation in the Palatini formalism, namely the Palatini Higgs inflation, is free from such a unitarity problem, although the UV cutoff of the model is still much below the Planck scale.
I then show that the Higgs inflation in the Einstein--Cartan gravity, namely the Einstein--Cartan Higgs inflation, can smoothly intepolate these two different models as its limits, so this model can serve as a general framework to systematically investigate the properties of Higgs inflation.
I finally discuss the UV property in this model and consider one particular UV-extension of Higgs inflation in this framework by considering the one-loop quantum effects.
Zoomlink: https://us06web.zoom.us/j/86508720881?pwd=e0U54YVQvz8qNhsWryU9xOD2yMNeUb.1