- May 26, 2022, 2:30 pm US/Central
- Wilson Hall, Curia II
- Toby Opferkuch, UC Berkeley
- Ryan Janish
Motivated by the prospect of discovering stochastic gravitational wave backgrounds, this talk will focus on the role(s) that non-minimally coupled scalar fields can play in the evolution of the early Universe. In the first part I will present a model for gravitational reheating involving a scalar field directly coupled to the Ricci curvature scalar. Crucial to the model is a period of kination after inflation, which causes the Ricci scalar to change sign inducing a tachyonic effective mass $m^2 \propto -H^2$ for the scalar. The resulting tachyonic growth of the scalar field provides the energy for reheating. This required period of kination necessarily leads to a blue-tilted primordial gravitational wave spectrum with the potential to be detected by future experiments. In addition I will discuss the case where the Higgs field plays the role of the scalar field. Finally, in the last part of my talk I will turn to on-going work simulating these systems on the lattice, where non-linear effects and backreactions between the various fields plays a crucial role.