Speaker
Description
In this talk, I will discuss the preheating dynamics in Higgs inflation in the Einstein-Cartan formalism, especially focusing on unitarity violation. It is known that Einstien-Cartan gravity provides a framework for a broad class of Higgs inflation models, including the metric and Palatini Higgs inflation. It smoothly connects these two limits by the coupling between Higgs and the Nieh-Yan term. The metric limit suffers from unitarity issue during preheating while the Palatini case is free from such problem. Therefore, it is expected that the Nieh-Yan coupling also controls the unitarity violation in the Einstein-Cartan framework. I will discuss how to calculate the particle production during preheating and how to determine the transition point that separates the unitarity-violating and unitarity-safe regimes in the parameter space of Einstein-Cartan Higgs inflation.